Patent Publication Number: US-2023138989-A1

Title: Shrimp processing apparatus and methods

Description:
RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. § 119 of U.S. Provisional Application Serial No. 62/971,653, filed 7 Feb. 2020, and titled SHRIMP PROCESSING SYSTEM, PROCESSING APPARATUS AND METHODS, which is incorporated herein by reference in its entirety. 
    
    
     FIELD 
     Shrimp processing systems including apparatus to measure, head, and/or sever the mud veins of shrimp, along with methods for measuring, heading, and mud vein severing are described herein. 
     BACKGROUND 
     The processing of shrimp for human consumption can include measurement of shrimp to properly group them according to size (with larger shrimp typically selling for more than smaller shrimp on a weight basis, e.g., pounds or kilograms). In some instances, that is the only processing performed, with consumers selecting whole shrimp and performing selected further processing at the time of preparing the shrimp for consumption. 
     Other shrimp processing may include removing the head of the shrimp (e.g., the carapace), removing the shell segments covering the abdomen and the associated swimmerets (e.g., pleopods), removing the mud vein of the shrimp, etc. 
     In many instances, the processing described above is accomplished manually -- even for commercial quantities of shrimp. Automated equipment designed to perform some shrimp processing often results in relatively high losses of consumable meat which, in turn, results in reduced revenue because shrimp is typically sold by weight. For example, peeling and deveining processes may involve slitting the back or dorsal side of the abdomen of the shrimp to remove the mud vein and, optionally, the shell segments on the abdomen. Such processing often results in the loss of meat and, therefore, a loss of revenue. 
     SUMMARY 
     Shrimp processing systems including apparatus to measure, head, and/or sever the mud veins of shrimp, along with methods for measuring, heading, and mud vein severing are described herein. The shrimp processing apparatus may be provided in systems may include one or more processing stations configured to perform one or more of the following functions on each shrimp: measurement of individual shrimp, severing the mud vein of individual shrimp, and heading of individual shrimp. 
     The shrimp processing systems and methods described herein provide, in one or more embodiments, for the processing of shrimp at one or a plurality of processing stations, with individual shrimp being transferred between stations using a conveying system. In one or more embodiments, the shrimp processing systems may include one or more processing stations configured to perform one or more of the following functions on each shrimp: measurement of individual shrimp, severing the mud vein of individual shrimp, heading of individual shrimp, peeling of individual shrimp; separating adjacent abdominal shell segments on individual shrimp, etc. 
     The shrimp processing systems and methods described herein may address a number of problems associated with the processing of shrimp for human consumption. Although many of the problems associated with shrimp processing and the solutions provided by the shrimp processing systems and methods described herein may be further described below, those problems may include, for example, inability to accurately size and sort shrimp, contamination of meat by viscera located in the carapace, loss of meat during the processing, failure to remove mud veins, etc. 
     Shrimp processing stations in shrimp processing systems as described herein may be described as data collection stations or functional stations. Collection of data regarding the physical characteristics of shrimp may be performed at processing stations characterized as data collection stations, while one or more physical characteristics of each shrimp may be changed at processing stations characterized as functional stations. One example of a data collection station may include, for example, a station in which the length, weight, etc. of a shrimp is measured/determined. Examples of functional stations may include, for example, mud vein severing stations, heading stations, peeling stations, shell segment separation stations, etc. The specific order of processing stations may be varied, for example, one or more data collection stations may be interspersed with one or more functional stations in any selected shrimp processing systems described herein. 
     Although processing stations may be identified as “data collection stations” or “functional stations,” a single processing station may be both a data collection station and a functional station. For example, it may be possible to both measure and sever the mud vein of a shrimp at a single processing station. Many other combinations of data collection and functional stations are possible in one or more embodiments of the shrimp processing systems and methods described herein. 
     The shrimp processing systems described herein may also be configured to transport each shrimp between processing stations using a conveying system connecting the processing stations. As used herein, a “conveying system” means a conveying system that is capable of transporting shrimp between processing stations without direct human intervention, i.e., the conveying system does not require a human to carry or otherwise transport the shrimp between processing stations. 
     One or more embodiments of the shrimp processing systems described herein may include processing stations arranged serially such that each shrimp passes through each type of processing station in the system. In such a system, the processing stations may or may not be activated as each shrimp passes through the processing station depending on whether the shrimp is to undergo the process performed at that station. 
     In one or more embodiments of the shrimp processing systems and methods described herein, individual shrimp may be restrained in a clamp configured to capture each shrimp proximate its tail. Accurately fixing the location of each shrimp on a clamp increases the accuracy and efficacy of a variety of processes that may be performed on each shrimp. In particular, accurately fixing the location of each shrimp allows for accurate measurement of the shrimp and location of various anatomical features that assist with processing the shrimp including, for example, severing of the mud vein at one or more selected locations, determining the size of the shrimp, removing the head of the shrimp (and any attached anatomical features), removing the shell of the shrimp, removing the pleopods of each shrimp, separating adjacent shell segments of each shrimp, etc. 
     In one or more embodiments of clamps used to restrain shrimp in shrimp processing systems and/or methods as described herein, the clamp may be configured to force the tail/uropod of the shrimp to fan open, with the opened tail assisting with retention of the shrimp by the clamp. In particular, the opened tail may resist removal of the shrimp from the clamp until such removal is desired. 
     In one or more embodiments of the shrimp processing systems and methods described herein in which the individual shrimp are measured to determine their size, the processing systems and methods may involve selectively processing the individual shrimp based on their size and/or sorting the shrimp after processing based on their size. In other words, the shrimp processing systems and methods described herein may allow for selective processing (e.g., peeling, heading, etc.) of shrimp of one or more sizes, while allowing other shrimp of one or more different sizes to pass through the processing system with the shell and/or head intact. Furthermore, shrimp of different sizes may be automatically sorted based on the size of the shrimp and, in the case of selective processing, whether those shrimp have been shelled, headed, etc. In still other embodiments, even shrimp of the same size may be selectively processed (e.g., shelled, headed, etc.) to allow for the sale of either shelled or shell-on as desired. 
     One type of shrimp processing station described herein may be described as a severing station in which the mud veins of individual shrimp are severed at selected locations along the abdomen of the shrimp. Severing the mud vein may facilitate removal of the mud vein from each shrimp during, for example, removal of the head/carapace from the abdomen of the shrimp, with the mud vein remaining attached to the viscera in the carapace of the shrimp as the carapace (and its associated anatomical features) is separated from the abdomen of the shrimp. In shrimp processing systems and methods in which the heading is performed by a machine (such as, e.g., the heading stations described herein), severing of the mud vein in each shrimp before heading may facilitate automated processing of the shrimp by providing shrimp that are substantially free of mud veins. Even in situations in which the heading is not performed by a machine but is, rather, performed manually, severing the mud vein prior to removal of the head of the shrimp may also facilitate removal of the mud vein with the carapace (and its associated anatomical features) to provide shrimp that are substantially free of mud veins. 
     As discussed herein, one or more embodiments of the processing systems and methods described herein may include a processing station in which the shrimp are each individually measured to determine their size. When combined with a processing station in which the mud veins of individual shrimp are severed, measuring each shrimp prior to the severing may assist in accurately severing the mud veins at one or more selected locations along the abdomens of the shrimp. While shrimp length can be used to determine the weight of the shrimp, shrimp length can also provide the location between selected shell segments on the abdomen of the shrimp and/or the location of the junction between the carapace and the abdomen. The location of the junction between, for example, the fifth and sixth shell segments on the abdomen of the shrimp can be generally correlated with the overall length of the shrimp. In one or more embodiments, the mud veins of shrimp may be severed at or near the junction between the fifth and sixth shell segments (or between the rearmost shell segment and an adjacent shell segment located closer to the carapace of the shrimp for shrimp that have more than six abdominal shell segments). Although severing of the mud vein at other selected locations is also possible, the junction between the rearmost and adjacent shell segments (for example, fifth and sixth shell segments) provides for removal of substantially all of the mud vein as the carapace is removed from the shrimp. 
     One or more embodiments of the shrimp processing systems described herein may also include a processing station in the form of a heading station in which the carapace and the viscera located therein is removed from the shrimp. Removal of the carapace using the heading stations and methods described herein also removes the anatomical features associated with the carapace such as, e.g., the short and long antennae, the scaphocerite, chela, rostrum, and many, if not all of the pereiopods. Moreover, the carapace and the viscera located therein are mechanically removed (as opposed to hydrodynamic removal used in some automated approaches) in a manner that avoids contamination of the meat by the viscera upon removal. In one or more embodiments of heading stations and methods described herein, the heading station may operate by determining the location of a junction between the carapace and the abdomen of each shrimp such that no significant portion of meat of the abdomen is removed along with the carapace. 
     Further, one or more embodiments of the heading stations and methods described herein may result in retention of additional meat (sometimes referred to as neck meat) on the abdomen of the shrimp. That additional meat adds to the weight of the shrimp and, therefore, may increase revenue generated by the sale of shrimp processed using the shrimp processing systems and methods described herein. 
     One or more embodiments of the shrimp processing systems described herein may also include a processing station in the form of a peeling station in which the abdominal shell segments are removed from the dorsal side of the abdomen of shrimp (the abdominal somites) as well as removing the pleopods (swimmerets) along with the pereiopods (walking legs) found on the ventral side of the abdomen of shrimp. In one or more alternative embodiments, the peeling station may only remove the pleopods (swimmerets) along with the pereiopods (walking legs) found on the ventral side of the abdomen of shrimp, leaving the shell segments on the dorsal side of the abdomen of shrimp intact. Doing so may provide shrimp that better retain flavor and/or firmness during storage, cooking, etc. 
     One potential advantage of the peeling stations and methods described herein is that the peeling process can, in one or more embodiments, be performed on raw shrimp held after harvesting for a significantly reduced amount of time (e.g., 2 hours or less, 1 hour or less, etc.) as compared to many peeling processes in which raw shrimp must be held after harvesting for relatively long periods of time (e.g., 24 hours or more) to improve the shell removal process. Holding raw shrimp after harvest for longer periods of time to improve peeling can, in some instances, result in loss of salable product due to spoilage, etc. In addition, holding raw shrimp after harvesting for longer periods of time to improve peeling can potentially be detrimental to firmness and flavor of the shrimp. 
     One or more embodiments of the shrimp processing systems described herein may include a processing station in the form of a shell segment separation station in which adjacent abdominal shell segments on the dorsal side of the abdomen of shrimp are separated. Separation of adjacent abdominal shell segments on the dorsal side of the abdomen of shrimp may assist with removal of the abdominal shell segments in, for example, a peeling station as described herein. In the absence of separation of adjacent abdominal shell segments on the dorsal side of the abdomen of a shrimp, some peeling processes may result in tearing or incomplete removal of one or more shell segments that are desired to be removed from the abdomen of a shrimp. In particular, it may be advantageous to separate the rearmost abdominal shell segment (that is, the shell segment closest to the tail of a shrimp) and the adjacent abdominal shell segment (that is, the shell segment located closer to the carapace of a shrimp) such that the adjacent abdominal shell segment and all shell segments located closer to the carapace can be cleanly removed without tearing of either the rearmost abdominal shell segment or the adjacent abdominal shell segment. 
     Although the processing stations described herein are discussed in connection with a shrimp processing system that includes two or more of the processing stations described herein, it should be understood that each processing station may, alone, constitute one or more aspects of the present invention. In other words, the invention may consist entirely of, in one aspect, a measuring station. In another aspect, the invention may consist entirely of a mud vein severing station. In another aspect, the invention may consist entirely of a heading station. In still another aspect, the invention may consist entirely of a peeling station. In still another aspect, the invention may consist entirely of an adjacent abdominal shell separation station. In yet another aspect, the invention may consist entirely of a clamp configured to retain a shrimp. In still other aspects, the invention may consist entirely of methods of performing one or more processes on a shrimp, e.g., measuring a shrimp, severing the mud vein of a shrimp at a selected location, heading a shrimp, separating adjacent abdominal shell segments on a shrimp, removing the pleopods and pereiopods found on the ventral side of the abdomen of a shrimp, peeling a shrimp, sorting shrimp, etc. 
     In a first aspect, one or more embodiments of a clamp configured to restrain a shrimp as described herein includes: a pair of jaws positioned on a base, wherein the pair of jaws comprises a first jaw and a second jaw facing each other across a clamping axis extending between the first jaw and the second jaw, wherein the first jaw comprises a first jaw face and the second jaw comprises a second jaw face, wherein the first jaw face faces the second jaw face along the clamping axis, wherein the first jaw face and the second jaw face define a receiving slot between the first jaw face and the second jaw face, wherein a distance between the first jaw face and the second jaw face across the receiving slot in a direction aligned with the clamping axis narrows when moving away from the base between the first jaw face and the second jaw face along a compression axis, wherein the compression axis extends through the base between the first jaw face and the second jaw face. The clamp further includes a spring member operably attached to the first jaw, the spring member configured to resist movement of the first jaw away from the second jaw along the clamping axis and the spring member configured to resist movement of the first jaw away from the base along a compression direction aligned with the compression axis, wherein a shrimp located between the pair of jaws is compressed against the base between the pair of jaws by the spring member and the first jaw. 
     In one or more embodiments of a clamp according to the first aspect, the clamp further comprises a body attached to the base, and wherein the spring member comprises an arm extending between the first jaw and the body, the arm configured to provide a compression force to the first jaw in response to movement of the first jaw away from the base in a direction aligned with the compression axis. 
     In one or more embodiments of a clamp according to the first aspect, the clamp further comprises a body attached to the base, and wherein the spring member comprises an arm extending between the first jaw and the body, the arm configured to provide a clamping force to the first jaw in response to movement of the first jaw away from the second jaw along the clamping axis. 
     In one or more embodiments of a clamp according to the first aspect, the clamp further comprises a body attached to the base, and wherein the spring member comprises an arm extending between the first jaw and the body, the arm configured to provide a compression force to the first jaw in response to movement of the first jaw away from the base in a direction aligned with the compression axis, and the arm configured to provide a clamping force to the first jaw in response to movement of the first jaw away from the second jaw along the clamping axis. 
     In one or more embodiments of a clamp according to the first aspect, the first jaw is configured to rotate about a first rotation axis extending between the first jaw and the base when a shrimp is located between the first jaw face and the second jaw face, and wherein, optionally, the first rotation axis extends through the arm extending between the first jaw and the body. In one or more embodiments, the first jaw comprises a first jaw standoff located proximate the first jaw face, wherein the first jaw standoff is located between the first jaw face and an outside portion of the first jaw, wherein the outside portion of the first jaw is spaced from the base to provide clearance for rotation of the first jaw about the first rotation axis. 
     In one or more embodiments of a clamp according to the first aspect, the spring member operably attached to the first jaw comprises a first spring member and the clamp comprises a second spring member operably attached to the second jaw, the second spring member configured to resist movement of the second jaw away from the first jaw along the clamping axis and the second spring member configured to resist movement of the second jaw away from the base along the compression direction aligned with the compression axis, wherein a tail of a shrimp located between the pair of jaws is forced against the base between the pair of jaws by the first spring member, the first jaw, the second spring member, and the second jaw. In one or more embodiments, the clamp further comprises a body attached to the base, and wherein the second spring member comprises an arm extending between the second first jaw and the body, the arm of the second spring member configured to provide a compression force to the second jaw in response to movement of the second jaw away from the base in a direction aligned with the compression axis. In one or more embodiments, the clamp further comprises a body attached to the base, and wherein the second spring member comprises an arm extending between the second jaw and the body, the arm of the second spring member configured to provide a clamping force to the second jaw in response to movement of the second jaw away from the first jaw along the clamping axis. In one or more embodiments, the clamp further comprises a body attached to the base, and wherein the second spring member comprises an arm extending between the second jaw and the body, the arm of the second spring member configured to provide a compression force to the second jaw in response to movement of the second jaw away from the base in a direction aligned with the compression axis, and the arm of the second spring member configured to provide a clamping force to the second jaw in response to movement of the second jaw away from the first jaw along the clamping axis. 
     In one or more embodiments of a clamp according to the first aspect, the second jaw is configured to rotate about a second rotation axis extending between the second jaw and the base when a shrimp is located between the first jaw face and the second jaw face, and wherein, optionally, the second rotation axis extends through the arm extending between the second jaw and the body. In one or more embodiments, the second jaw comprises a second jaw standoff located proximate the second jaw face, wherein the second jaw standoff is located between the second jaw face and an outside portion of the second jaw, wherein the outside portion of the second jaw is spaced from the base to provide clearance for rotation of the second jaw about the second rotation axis. 
     In one or more embodiments of a clamp according to the first aspect, a distance between the body and the receiving slot in a direction transverse to the clamping axis is selected to allow the tail of a shrimp captured in the clamp to be positioned between the receiving slot and the body. 
     In one or more embodiments of a clamp according to the first aspect, a distance between the body and the receiving slot in a direction transverse to the clamping axis is 4 or more, 6 or more, 8 or more, 10 or more times, 14 or more, 16 or more, 18 or more, or 20 or more times a slot width measured at a midpoint between the base and the narrowest portion of the receiving slot as measured along the clamping axis direction, and, optionally, wherein the distance between the body and the receiving slot in the direction transverse to the clamping axis is 24 or less, 22 or less, 20 or less, 18 or less, or 16 or less times the slot width measured at a midpoint between the base and the narrowest portion of the receiving slot as measured along the clamping axis direction. 
     In a second aspect, one or more embodiments of a method of restraining a shrimp as described herein includes: providing a clamp comprising a first jaw and a second jaw positioned on a base, wherein the first jaw faces the second jaw, and wherein the first jaw and the second jaw define a receiving slot between the first jaw and the second jaw; inserting a shrimp into the receiving slot between the first and second jaws such that the tail of the shrimp is located on a clamp side of the first and second jaws and the carapace of the shrimp is located on a processing side of the first and second jaws; and forcing the tail of the shrimp towards the base using the first jaw after inserting the shrimp into the receiving slot between the first and second jaws. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, forcing the tail of the shrimp towards the base using the first jaw causes the tail to form a splayed tail fan on the clamp side of the first and second jaws. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, forcing the tail of the shrimp towards that base using the first jaw comprises applying a persistent compressive force on the shrimp in a compression direction aligned with a compression axis extend through base and the receiving slot between the first and second jaws using the first jaw after inserting the shrimp into the receiving slot. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, forcing the tail of the shrimp towards the base using the first jaw comprises applying a persistent compressive force on the shrimp in a compression direction aligned with a compression axis extend through base and the receiving slot between the first and second jaws using the second jaw after inserting the shrimp into the receiving slot. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, forcing the tail of the shrimp towards the base using the first jaw comprises applying a persistent compressive force on the shrimp in a compression direction aligned with a compression axis extend through base and the receiving slot between the first and second jaws using the first jaw and the second jaw after inserting the shrimp into the receiving slot. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, the method comprises applying a persistent clamping force on the shrimp along a clamping direction aligned with a clamping axis extending through the first and second jaws using the first jaw after inserting the shrimp into the receiving slot. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, the method comprises applying a persistent clamping force on the shrimp along a clamping direction aligned with a clamping axis extending through the first and second jaws using the second jaw after inserting the shrimp into the receiving slot. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, the method comprises applying a persistent clamping force on the shrimp along a clamping direction aligned with a clamping axis extending through the first and second jaws using the first jaw and the second jaw after inserting the shrimp into the receiving slot. 
     In one or more embodiments of methods of restraining shrimp according to the second aspect, the clamp comprises a body, and wherein the first jaw is connected to the body through a first arm, and wherein the first jaw rotates about a first rotation axis located above the base extending between the first jaw and the body when inserting a shrimp into the receiving slot. In one or more embodiments, the second jaw is connected to the body through a second arm and the second jaw is attached to the body through a second arm, and wherein the second jaw rotates about a second rotation axis located above the base and extending between the second jaw and the body when inserting a shrimp into the receiving slot. 
     In a third aspect, one or more embodiments of a mud vein severing apparatus as described herein includes: a vein severing module comprising a blade comprising a sharpened working edge and a blade actuator configured to move the blade between a stored position and a severed position; an optional measurement module configured to measure a length of a shrimp held in a clamp moving through the measurement module along a measurement direction; a controller operably connected to the blade actuator and the optional measurement module, wherein the controller is configured to: optionally receive a signal indicative of the length of the shrimp from the measurement module; and activate the blade actuator to move the blade from the stored position to the severed position when a shrimp is in a selected severing location, wherein the blade actuator moves the blade along a severing path generally transverse to the measurement direction. 
     In a fourth aspect, one or more embodiments of a method of severing a mud vein of a shrimp as described herein includes: positioning a shrimp in a selected severing location; and moving a blade through the shrimp along a severing path oriented generally transverse to a length of the shrimp as measured from a carapace to a tail of the shrimp, wherein the blade passes through a shell of the shrimp at a selected depth proximate a junction between a rearmost abdominal shell segment and an adjacent abdominal shell segment of the shrimp, wherein the rearmost abdominal shell segment is located between the adjacent abdominal shell segment and the tail of the shrimp. 
     In a fifth aspect, one or more embodiments of a shrimp heading apparatus as described herein includes: a heading restraint positioned opposite a working surface; a heading restraint actuator configured to move the heading restraint between a stored position and restraint position relative to the working surface, wherein the heading restraint is spaced from the working surface to allow for positioning of a shrimp between the heading restraint and the working surface when the heading restraint is in the stored position, and wherein the heading restraint is closer to the working surface when the heading restraint is in the restraint position than when the heading restraint is in the stored position such that the heading restraint is configured to force a shrimp located between the heading restraint and the working surface against the working surface when the heading restraint is in the restraint position; a spoon; a spoon actuator configured to move the spoon along a spoon path between a ready position and finish position relative to the heading restraint, wherein a working portion of the spoon is proximate a carapace side of the heading restraint when the spoon is in the ready position and wherein the working portion of the spoon is spaced away from the carapace side of the heading restraint when the spoon is in the finish position such that the working portion of the spoon is configured to separate a head of a shrimp on the working surface from an abdomen of the shrimp when the spoon moves from the ready position to the finish position; and a controller operably connected to the heading restraint actuator and the spoon actuator, the controller configured to: operate the heading restraint actuator to move the heading restraint from the stored position to the restraint position, operate the spoon actuator to move the spoon along the spoon path from the ready position to the finish position after operating the head restraint actuator to move the heading restraint to the restraint position, and operate the heading restraint actuator to return the heading restraint to the stored position after operating the spoon actuator to move the spoon to the finish position. 
     In a sixth aspect, one or more embodiments of a method of removing a head of a shrimp, the method comprising: restraining an abdomen of a shrimp in a fixed position on a working surface; moving a spoon through the shrimp proximate a carapace junction of the shrimp, wherein the carapace junction is located between a carapace and a first abdominal segment of the shrimp; and moving the spoon away from the abdomen while restraining the abdomen of the shrimp in the fixed position on the working surface, wherein moving the spoon away from the abdomen separates the carapace of the shrimp from the abdomen of the shrimp. 
     In a seventh aspect, one or more embodiments of a shrimp peeling apparatus as described herein includes: a lower roller assembly comprising a first lower roller, a second lower roller, and a lower roller assembly drive operably connected to the first and second lower rollers, wherein the lower roller assembly drive is configured to rotate the first lower roller about a first lower roller axis and rotate the second lower roller about the second lower roller axis, wherein the first lower roller axis is aligned with the second lower roller axis; an upper roller assembly comprising a first upper roller, a second upper roller, and an upper roller assembly drive operably connected to the first and second upper rollers, wherein the upper roller assembly drive is configured to rotate the first upper roller about a first upper roller axis and rotate the second upper roller about the second upper roller axis, wherein the first upper roller axis is aligned with the second upper roller axis, and wherein the first upper roller extends from a tail end to a head end along the first upper roller axis, and further wherein the second upper roller extends from a tail end to a head end along the second upper roller axis; a roller shuttle configured to move one or both of the lower roller assembly and the upper roller assembly between a receiving position and an operating position, wherein the lower roller assembly and the upper roller assembly are located farther from each other in a direction transverse to the first lower roller axis and the first upper roller axis when the lower roller assembly and the upper roller assembly are in the receiving position than when the lower roller assembly and the upper roller assembly are in the operating position; and a controller operably connected to the lower roller assembly drive, upper roller assembly drive, and the roller shuttle, the controller configured to: operate the roller shuttle to move one or both of the lower roller assembly and the upper roller assembly between the receiving position and the operating position; operate the lower roller assembly drive to rotate the first lower roller about the first lower roller axis over a first capture arc and rotate the second lower roller about the second lower roller axis over a second capture arc, wherein the first lower roller and second lower roller rotate in opposite directions over their respective capture arcs; operate the roller shuttle to move the lower roller assembly and the upper roller assembly from the receiving position to the operating position after rotating the first lower roller and second lower roller in opposite directions over their respective capture arcs; operate the upper roller assembly drive to rotate the first upper roller about the first upper roller axis over a first peeling arc and rotate the second upper roller about the second lower roller axis over a second peeling arc, wherein the first upper roller and the second upper roller rotate in opposite directions over their respective peeling arcs after the roller shuttle moves the lower roller assembly and the upper roller assembly from the receiving position to the operating position; and operate the lower roller assembly drive to rotate the first lower roller about the first lower roller axis over a first removal arc and rotate the second lower roller about the second lower roller axis over a second removal arc, wherein the first lower roller and the second lower roller rotate in opposite directions over their respective removal arcs while the lower roller assembly and the upper roller assembly are in the operating position; wherein the controller is configured to operate upper roller assembly drive to rotate the upper first and second upper rollers in opposite directions over their respective peeling arcs while operating the lower roller assembly drive to rotate the first and second lower rollers in opposite directions over their respective removal arcs. 
     In an eighth aspect, one or more embodiments of a shrimp processing apparatus in the form of peeling apparatus configured to remove pleopods and/or swimmerets from shrimp as described herein includes: a lower roller assembly comprising a first lower roller, a second lower roller, and a lower roller assembly drive operably connected to the first and second lower rollers, wherein the lower roller assembly drive is configured to rotate the first lower roller about a first lower roller axis and rotate the second lower roller about the second lower roller axis, wherein the first lower roller axis is aligned with the second lower roller axis; an upper assembly; a roller shuttle configured to move one or both of the lower roller assembly and the upper assembly between a receiving position and an operating position, wherein the lower roller assembly and the upper assembly are located farther from each other in a direction transverse to the first lower roller axis and the first upper roller axis when the lower roller assembly and the upper assembly are in the receiving position than when the lower roller assembly and the upper assembly are in the operating position; and a controller operably connected to the lower roller assembly drive and the roller shuttle, the controller configured to: operate the roller shuttle to move one or both of the lower roller assembly and the upper assembly between the receiving position and the operating position; operate the lower roller assembly drive to rotate the first lower roller about the first lower roller axis over a first capture arc and rotate the second lower roller about the second lower roller axis over a second capture arc, wherein the first lower roller and second lower roller rotate in opposite directions over their respective capture arcs; operate the roller shuttle to move the lower roller assembly and the upper assembly from the receiving position to the operating position after rotating the first lower roller and second lower roller in opposite directions over their respective capture arcs; and operate the lower roller assembly drive to rotate the first lower roller about the first lower roller axis over a first removal arc and rotate the second lower roller about the second lower roller axis over a second removal arc, wherein the first lower roller and the second lower roller rotate in opposite directions over their respective removal arcs while the lower roller assembly and the upper assembly are in the operating position. 
     In a ninth aspect, one or more embodiments of a method of peeling a shrimp as described herein may include: capturing at least one pleopod attached to an abdomen of a shrimp between a first lower roller and a second lower roller by rotating each of the first and second lower rollers over a capture arc, wherein the first and second lower rollers are rotated in opposite directions; contacting the abdominal shell segments of the shrimp with a first upper roller and a second upper roller after rotating the first and second lower rollers over their respective capture arcs; rotating the first upper roller over a first peeling arc and rotating the second upper roller over a second peeling arc, wherein the first and second upper rollers are rotated in opposite directions over their respective peeling arcs; and rotating the first lower roller over a first removal arc and rotating the second lower roller over a second removal arc, wherein the first lower roller and the second lower roller rotate in opposite directions over their respective removal arcs; wherein, after contacting the abdominal shell segments of the shrimp with a first upper roller and a second upper roller, the method comprises rotating the first and second upper rollers over their respective peeling arcs while rotating the first and second lower rollers over their respective removal arcs. 
     In a tenth aspect, one or more embodiments of a method of peeling a shrimp to remove only its pleopods and/or swimmerets as described herein may include: capturing a plurality of pleopods attached to an abdomen of a shrimp between a first lower roller and a second lower roller by rotating each of the first and second lower rollers over a capture arc, wherein the first and second lower rollers are rotated in opposite directions; contacting the abdominal shell segments of the shrimp with an upper assembly after rotating the first and second lower rollers over their respective capture arcs; and rotating the first lower roller over a first removal arc and rotating the second lower roller over a second removal arc after contacting the abdominal shell segments of the shrimp with the upper assembly, wherein the first lower roller and the second lower roller rotate in opposite directions over their respective removal arcs. 
     In an eleventh aspect, one or more embodiments of a shell segment separator apparatus as described herein may include: a first shell segment retainer positioned opposite a working surface; a second shell segment retainer positioned opposite the working surface; a first retainer actuator operably connected to the first shell segment retainer and configured to move the first shell segment retainer from a ready configuration to a retention configuration, wherein the first shell segment retainer is configured to allow for positioning of a shrimp between the first shell segment retainer and the working surface when the first shell segment retainer is in the ready configuration, and wherein the first shell segment retainer is configured to retain a first shell segment of a shrimp located between first shell segment retainer and the working surface in a selected location on the working surface when the first shell segment retainer is in the retention configuration; a second retainer actuator operably connected to the second shell segment retainer and configured to move the second shell segment retainer from a ready configuration to a retention configuration, wherein the second shell segment retainer is configured to allow for positioning of a shrimp between the second shell segment retainer and the working surface when the second shell segment retainer is in the ready configuration, and wherein the second shell segment retainer is configured to retain a second shell segment of a shrimp located between second shell segment retainer and the working surface in a selected location relative to the second shell segment retainer when the second shell segment retainer is in the retention configuration; a separation actuator operably connected to the second shell segment retainer, the separation actuator configured to move one or both of the first shell segment retainer and the second shell segment retainer between an initial position and a separation position relative to each other, wherein the second shell segment retainer is located further away from the first shell segment retainer when the first shell segment retainer and the second shell segment retainer are in the separation position than when the first shell segment retainer and the second shell segment retainer are in the initial position, wherein one or both of the first shell segment retainer and the second shell segment retainer move along a processing axis when moving between the initial position and the separation position; and a controller operably connected to the first retainer actuator, the second retainer actuator, and the separation actuator, wherein the controller is configured to: operate the first retainer actuator to move the first shell segment retainer from the ready configuration to the retention configuration; operate the second retainer actuator to move the second shell segment retainer from the ready configuration to the retention configuration; and operate the separation actuator to move one or both of the first shell segment retainer and the second shell segment retainer such that the first shell segment retainer and the second shell segment retainer move from the initial position to the separation position after operating the first retainer actuator to move the first shell segment retainer from the ready configuration to the retention configuration and after operating the second retainer actuator to move the second shell segment retainer from the ready configuration to the retention configuration. 
     In a twelfth aspect, one or more embodiments of a method of separating adjacent shell segments on an abdomen of a shrimp as described herein may include: retaining a first shell segment on an abdomen of a shrimp, wherein the first shell segment is optionally retained in a fixed location relative to a processing axis, and wherein the abdomen of the shrimp is aligned with the processing axis; and moving a second shell segment on the abdomen of the shrimp away from the first shell segment in a direction aligned with the processing axis while, optionally, retaining the first shell segment in the fixed location, wherein the second shell segment is adjacent the first shell segment; wherein the first shell segment and the second shell segment remain attached to the abdomen of the shrimp after moving the second shell segment away from the first shell segment. 
     In a thirteenth aspect, one or more embodiments of a shrimp processing system as described herein may include: a plurality of clamps, wherein each clamp of the plurality of clamps is configured to hold a shrimp proximate a tail of the shrimp; a plurality of processing stations comprising at least one data collection station capable of collecting data regarding a shrimp held in each clamp of the plurality of clamps and at least one functional station capable of changing the shrimp held in each clamp of the plurality of clamps; a conveying system connecting the plurality of processing stations, the conveying system configured to move the plurality of clamps between the plurality of processing stations; and a controller operably connected to the conveying system and the plurality of processing stations, the controller configured to: operate the conveying system such that the plurality of clamps are moved through the plurality of processing stations; and selectively activate each processing station of the plurality of processing stations. 
     In one or more embodiments of the shrimp processing systems described herein, the plurality of clamps are magnetically attached to the conveying system. 
     In one or more embodiments of the shrimp processing systems described herein, the conveying system comprises a plurality of clamp mounts, wherein the plurality of clamps are attached to the conveying system through the plurality of clamp mounts. In one or more embodiments, two or more clamps of the plurality of clamps are attached to each clamp mount of the plurality of clamp mounts. 
     In one or more embodiments of the shrimp processing systems described herein, the clamp mounts are magnetically attached to the conveying system. 
     In one or more embodiments of the shrimp processing systems described herein, the conveying system comprises a plurality of mounting bosses, wherein each clamp mount comprises one or more blocks, wherein each block is configured to attach to one mounting boss of the plurality of mounting bosses. In one or more embodiments, the mounting boss and the block of one or more attached pairs of mounting bosses and blocks each comprise a pair of permanent magnets, wherein the pairs of permanent magnets in the mounting boss and the attached block form closed magnetic fields. In one or more embodiments, the mounting boss and the block of one or more attached pairs of mounting bosses and blocks are attached to each other using one or more of: mechanical fasteners, adhesives, and interlocking mechanical connections. 
     In one or more embodiments of the shrimp processing systems described herein, the conveying system comprises one or more belts extending between the plurality of processing stations, wherein the one or more belts moved through the plurality of processing stations along a conveying direction, and wherein the plurality of mounting bosses are attached to the one or more belts, and further wherein the plurality of mounting bosses are cantilevered over the one or more belts to which the plurality of mounting bosses are attached. In one or more embodiments, the plurality of mounting bosses cantilevered over the one or more belts to which the plurality of mounting bosses are attached are cantilevered over the one or more belts along their leading edges as defined by the conveying direction. 
     In one or more embodiments of the shrimp processing systems described herein, the plurality of mounting bosses cantilevered over the one or more belts to which the plurality of mounting bosses are attached are cantilevered over the one or more belts along their trailing edges as defined by the conveying direction. 
     In one or more embodiments of the shrimp processing systems described herein, the conveying system advances the plurality of clamps from a loading end to an ejection end, and wherein the conveying system comprises an ejection station at the ejection end, the ejection station configured to eject shrimp held in the plurality of clamps from the plurality of clamps. 
     In one or more embodiments of the shrimp processing systems described herein, the ejection station comprises a plurality plungers, wherein each plunger of the plurality of plungers comprises a retracted position an ejection position, and wherein movement of the plunger from the retracted position to the ejection position in the presence of a shrimp held in a clamp at the ejection station forces the shrimp from the clamp. In one or more embodiments, the plunger is configured to act on an abdominal segment adjacent the clamp. 
     In one or more embodiments of the shrimp processing systems described herein, each clamp of the plurality of clamps comprises: a pair of jaws positioned on a base, wherein the pair of jaws comprises a first jaw and a second jaw facing each other across a clamping axis extending between the first jaw and the second jaw, wherein the first jaw comprises a first jaw face and the second jaw comprises a second jaw face, wherein the first jaw face faces the second jaw face along the clamping axis, wherein the first jaw face and the second jaw face define a receiving slot between the first jaw face and the second jaw face, wherein a distance between the first jaw face and the second jaw face across the receiving slot in a direction aligned with the clamping axis narrows when moving away from the base between the first jaw face and the second jaw face along a compression axis, wherein the compression axis extends through the base between the first jaw face and the second jaw face; and a spring member operably attached to the first jaw, the spring member configured to resist movement of the first jaw away from the second jaw along the clamping axis and the spring member configured to resist movement of the first jaw away from the base along a compression direction aligned with the compression axis, wherein a shrimp located between the pair of jaws is compressed against the base between the pair of jaws by the spring member and the first jaw. 
     In one or more embodiments of the shrimp processing systems described herein, a data collection station of the plurality of processing stations comprises a measurement station configured to measure a length of a shrimp held in each clamp of the plurality of clamps. 
     In one or more embodiments of the shrimp processing systems described herein, a functional station of the plurality of processing stations comprises a mud vein severing apparatus configured to sever a mud vein of a shrimp. 
     In one or more embodiments of the shrimp processing systems described herein, a functional station of the plurality of processing stations comprises a heading apparatus configured to remove a head of a shrimp. 
     In one or more embodiments of the shrimp processing systems described herein, a functional station of the plurality of processing stations comprises a peeling apparatus configured to remove a shell of a shrimp. 
     In one or more embodiments of the shrimp processing systems described herein, a functional station of the plurality of processing stations comprises a shell segment separator apparatus configured to separate a pair of adjacent shell segments of a shrimp. 
     In one or more embodiments of the shrimp processing systems described herein, the plurality of processing stations comprises two or functional stations selected from the group of: a mud vein severing apparatus configured to sever a mud vein of a shrimp, a heading apparatus configured to remove a head of a shrimp, a peeling apparatus configured to remove a shell of a shrimp, and a shell segment separator apparatus configured to separate a pair of adjacent shell segments of a shrimp. 
     In one or more embodiments of the shrimp processing systems described herein, the at least one data collection station comprises a measurement module configured to measure a length of a shrimp held in a clamp of the plurality of clamps moving through the measurement module along a measurement direction, the measurement module comprising a non-contact sensor configured to detect the clamp and a shrimp held in the clamp, the non-contact sensor operably connected to the controller to deliver signals indicative of energy received by the non-contact sensor, wherein the controller is further configured to: identify a junction between a clamp and a shrimp held in the clamp when moving a shrimp held in the clamp through the non-contact sensor based on a signal received from the non-contact sensor; determine a length of a shrimp held in a clamp after identifying the junction between a clamp and a shrimp held in a clamp based at least in part on a signal received from the non-contact sensor; and optionally, determine a weight of a shrimp held in a clamp after determining the length of a shrimp held in a clamp based at least in part on the length of a shrimp held in a clamp. In one or more embodiments, the controller is configured to identify a junction between a clamp and a shrimp when the signal received from the non-contact sensor reaches or falls below a selected clamp threshold value. 
     In one or more embodiments of the shrimp processing systems described herein, the controller is configured to determine a length of a shrimp when the signal received from the non-contact sensor reaches or exceeds a selected antenna threshold value. 
     In one or more embodiments of the shrimp processing systems described herein, the non-contact sensor comprises an optical sensor or an ultrasonic sensor. 
     In one or more embodiments of the shrimp processing systems described herein, the controller is configured to operate the non-contact sensor to calibrate the non-contact sensor before every shrimp held in a clamp passes through the non-contact sensor in the measurement direction. 
     In one or more embodiments of the shrimp processing systems described herein, the controller is configured to operate the non-contact sensor to calibrate the non-contact sensor after a selected number of shrimp held in a clamp pass through the non-contact sensor in the measurement direction. 
     In one or more embodiments of the shrimp processing systems described herein, the controller comprises a central controller controlling the conveying system and the plurality of processing stations. 
     In a fourteenth aspect, one or more embodiments of a method of processing shrimp as described herein may include: loading individual shrimp into each clamp of a plurality of clamps to provide a plurality of loaded clamps, wherein each loaded clamp restrains only one individual shrimp at a time; transporting each loaded clamp between a plurality of processing stations using a conveying system connecting the plurality of processing stations; collecting data on each shrimp in the plurality of loaded clamps in at least one processing station of the plurality of processing stations; and performing one or more actions on each shrimp in the plurality of loaded clamps in at least one processing station of the plurality of processing stations. 
     In one or more embodiments of methods of processing shrimp as described herein, the method comprises: loading individual shrimp into each clamp of a plurality of clamps to provide a plurality of loaded clamps, wherein each loaded clamp restrains only one individual shrimp at a time; transporting each loaded clamp between a plurality of processing stations using a conveying system connecting the plurality of processing stations; collecting data on each shrimp in the plurality of loaded clamps in at least one processing station of the plurality of processing stations; and performing one or more actions on each shrimp in the plurality of loaded clamps in at least one processing station of the plurality of processing stations. 
     In one or more embodiments of methods of processing shrimp as described herein, the plurality of clamps are arranged in groups of two or more clamps on the conveying system, wherein transporting each loaded clamp between the plurality of processing stations comprises simultaneously transporting the groups of two or more clamps between the plurality of processing stations. 
     In one or more embodiments of methods of processing shrimp as described herein, the plurality of processing stations are arranged in groups of two or more processing stations, wherein the method comprises: transporting the groups of two or more clamps between the groups of two or more processing stations; collecting data on the shrimp in each group of two or more clamps at each group of two more processing stations configured to collect data before transporting each group of two or more clamps out of the group of two or more processing stations; and performing one or more actions on the shrimp in each group of two or more clamps at each group of two or more processing stations configured to perform one or more actions before transporting each group of two or more clamps out of the group of two or more processing stations configured to perform one or more actions. 
     In one or more embodiments of methods of processing shrimp as described herein, collecting data comprises measuring a length of each shrimp and, optionally, assigning a weight to each shrimp based at least in part on the length of each shrimp. In one or more embodiments, measuring the length of each shrimp comprises measuring the length of each shrimp according to any one of the methods of measuring shrimp as described herein. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises severing a mud vein at a selected location on each shrimp, wherein the method comprises identifying the selected location based at least in part on the length of each shrimp. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises severing a mud vein at a selected location on each shrimp. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises removing a head from each shrimp. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises severing a mud vein on each shrimp proximate a tail of the shrimp before removing the head from each shrimp. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises severing a mud vein on each shrimp proximate a tail of the shrimp and, optionally, removing a head from each shrimp after severing the mud vein. 
     In one or more embodiments of methods of processing shrimp as described herein, the method comprises identifying a carapace junction between the carapace and the abdomen of each shrimp before removing the head from each shrimp. In one or more embodiments, identifying the carapace junction and removing the head of the shrimp are performed at a single processing station. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises removing abdominal shell segments from each shrimp. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises removing one or more pleopods from each shrimp. 
     In one or more embodiments of methods of processing shrimp as described herein, performing one or more actions on each shrimp comprises simultaneously removing abdominal shell segments and one or more pleopods from each shrimp. 
     In a fifteenth aspect, one or more embodiments of a method of measuring shrimp held in a clamp comprise: moving a shrimp held in a clamp through a non-contact sensor along a measurement direction; identifying a junction between the clamp and the shrimp when moving a shrimp held in the clamp based on a signal received from the non-contact sensor; determining a length of the shrimp held in the clamp after identifying the junction between a clamp and a shrimp held in a clamp based at least in part on a signal received from the non-contact sensor as the shrimp passes through the non-contact sensor; and optionally, determining a weight of the shrimp held in the clamp after determining the length of the shrimp, the weight being based at least in part on the length of the shrimp. 
     In one or more embodiments of methods of measuring shrimp according to the fifteenth aspect, the junction between the clamp and the shrimp comprises determining when the signal received from the non-contact sensor reaches or falls below a selected clamp threshold value. 
     In one or more embodiments of methods of measuring shrimp according to the fifteenth aspect, determining the length of the shrimp comprises determining when the signal received from the non-contact sensor reaches or exceeds a selected antenna threshold value indicting that at least one antenna of the shrimp is passing through the non-contact sensor. 
     In one or more embodiments of methods of measuring shrimp according to the fifteenth aspect, the non-contact sensor comprises an optical sensor or an ultrasonic sensor. 
     In one or more embodiments of methods of measuring shrimp according to the fifteenth aspect, the method further comprises calibrating the non-contact sensor before every shrimp held in a clamp passes through the non-contact sensor in the measurement direction. 
     In one or more embodiments of methods of measuring shrimp according to the fifteenth aspect, the method further comprises calibrating the non-contact sensor after a selected number of the shrimp pass through the non-contact sensor in the measurement direction. 
     In a sixteenth aspect, one or more embodiments of a clamp configured to restrain a shrimp as described herein may include: a pair of jaws positioned on a base, wherein the pair of jaws comprises a first jaw and a second jaw facing each other across a clamping direction; wherein the first jaw comprises a first jaw face and the second jaw comprises a second jaw face, wherein the first jaw face faces the second jaw face across the clamping direction; wherein the first jaw face and the second jaw face define a receiving slot between the first jaw face and the second jaw face, wherein a distance between the first jaw face and the second jaw face in the clamping direction narrows when moving away from the base between the first jaw face and the second jaw face in a compression direction transverse to the clamping direction; biasing means operably attached to the pair of jaws, the biasing means resisting movement of the first jaw away from the second jaw along the clamping direction and the biasing means resisting movement of the first jaw away from the base along the compression direction, wherein a tail of a shrimp located between the pair of jaws is compressed against the base between the pair of jaws by the first jaw. 
     In a seventeenth aspect, one or more embodiments of a clamp configured to restrain a shrimp as described herein may include: a pair of jaws positioned on a base, wherein the pair of jaws comprises a first jaw and a second jaw facing each other across a clamping direction; wherein the first jaw and the second jaw define a receiving slot between the first jaw and the second jaw, wherein a width of the receiving slot in the clamping direction narrows when moving away from the base between the first jaw and the second jaw in a compression direction transverse to the clamping direction; wherein the clamp is configured to apply a clamping force and a compression force to a tail of a shrimp located between the pair of jaws, wherein the clamping force acts in the clamping direction and wherein the compression force urges the tail towards the base. 
     As used herein, the term “shrimp” should be construed to refer to crustaceans harvested for human consumption that are referred to as either shrimp or prawns in, for example, the sub-orders Pieocyemata (Shrimp) and Dendrobranchiata (Prawns). Further, because the physical characteristics of shrimp capable of being processed using the shrimp processing systems and methods described herein can vary widely, any dimensions discussed herein are provided only as a general guide and further refinement of any such dimensions may be required to optimize operation of the shrimp processing systems and methods described herein based on for example, the size, species, and/or general conditions of shrimp being processed. 
     If used herein, relational terms such as above, below, top, bottom, etc. are (unless otherwise specified in this description and/or the claims) used only to facilitate description of the various features of the shrimp processing systems and methods described herein and should not be construed to require any specific orientation of the shrimp processing systems, the shrimp being processed by the systems, and/or the methods described herein. 
     If used herein, the term “substantially” has the same meaning as “significantly,” and can be understood to modify the term that follows by at least about 75%, at least about 90%, at least about 95%, or at least about 98%. The term “not substantially” as used herein has the same meaning as “not significantly,” and can be understood to have the inverse meaning of “substantially,” i.e., modifying the term that follows by not more than 25%, not more than 10%, not more than 5%, or not more than 2%. 
     Numeric values used herein include normal variations in measurements as expected by persons skilled in the art and should be understood to have the same meaning as “approximately” and to cover a typical margin of error, such as ±5 % of the stated value. 
     Terms such as “a,” “an,” and “the” are not intended to refer to only a singular entity but include the general class of which a specific example may be used for illustration. 
     The terms “a,” “an,” and “the” are used interchangeably with the term “at least one.” The phrases “at least one of” and “comprises at least one of” followed by a list refers to any one of the items in the list and any combination of two or more items in the list. 
     As used here, the term “or” is generally employed in its usual sense including “and/or” unless the content clearly dictates otherwise. The term “and/or” means one or all of the listed elements or a combination of any two or more of the listed elements. 
     The recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc. or 10 or less includes 10, 9.4, 7.6, 5, 4.3, 2.9, 1.62, 0.3, etc.). Where a range of values is “up to” or “at least” a particular value, that value is included within the range. 
     The words “preferred” and “preferably” refer to embodiments that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the disclosure, including the claims. 
     The above summary of the invention is not intended to describe each embodiment or every implementation of the shrimp processing systems, processing stations, and methods described herein. Rather, a more complete understanding of the invention will become apparent and appreciated by reference to the following description of illustrative embodiments and claims in view of the accompanying figures of the drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG.  1 A  is a block diagram of one illustrative embodiment of a shrimp processing system as described herein. 
         FIG.  1 B  is a perspective view of one illustrative embodiment of an unloading station that may be used to unload or eject shrimp that have been processed in the shrimp processing systems described herein. 
         FIG.  1 C  is a side view of the unloading station depicted in  FIG.  1 B  after ejection/unloading of a shrimp from a clamp as described herein. 
         FIG.  2    is a block diagram of a control system that may be implemented in one illustrative embodiment of a shrimp processing system as described herein. 
         FIG.  3    depicts one illustrative embodiment of a shrimp that may be processed using one or more embodiments of the shrimp processing systems and methods as described herein. 
         FIG.  4    is a perspective view of one illustrative embodiment of a clamp that may be used to restrain shrimp as described herein. 
         FIG.  5    is an enlarged front view of the clamp of  FIG.  4    in a direction transverse to both axes  121  and  123 . 
         FIG.  6    is a top plan view of the clamp of  FIG.  4    with a shrimp retained therein. 
         FIG.  7    is a perspective view of one portion of a shrimp processing system including illustrative embodiments of clamps mounted on illustrative embodiments of clamp mounts that are, in turn, attached to illustrative embodiments of conveying elements of a conveying system to facilitate movement of shrimp through a processing system according to the methods described herein. 
         FIG.  8    is an exploded diagram depicting one illustrative embodiment of structures used to attach clamp mounts to conveying elements in one or more embodiments of shrimp processing systems as described herein. 
         FIG.  9    is an enlarged view of the structures of  FIG.  8    after assembly with portions of the structures depicted as being transparent to allow visualization of components located therein. 
         FIG.  10    is an enlarged cross-sectional view of  FIG.  9    taken along line 10-10 in  FIG.  9   . 
         FIG.  11    depicts shrimp retained in clamps on a clamp mount as depicted in  FIGS.  7 - 10   . 
         FIGS.  12 - 13    depict one alternative embodiment of a clamp and clamp mount system that may be used in connection with the processing systems and methods described herein. 
         FIG.  14    depicts another alternative embodiment of a clamp and clamp mount system that may be used in connection with the processing systems and methods described herein. 
         FIG.  15    is a block diagram of a control system that may be implemented in one illustrative embodiment of an integrated measurement and mud vein severing apparatus used in one or more shrimp processing systems as described herein. 
         FIGS.  16 - 21    depict various views of one illustrative embodiment of a mud vein severing apparatus as described herein. 
         FIG.  22    depicts one illustrative embodiment of a blade that may be used in one or more embodiments of a mud vein severing apparatus as described herein. 
         FIG.  23    depicts the severing restraint of the mud vein severing apparatus depicted in  FIGS.  16 - 21    in position on a larger shrimp (with the shrimp being depicted in a cross-sectional view). 
         FIG.  24    depicts the severing restraint of the mud vein severing apparatus depicted in  FIG.  23    in position on a smaller shrimp (with the shrimp also being depicted in a cross-sectional view). 
         FIG.  25 A  depicts one illustrative embodiment of a severing restraint that may be used in one or more embodiments of a mud vein severing apparatus as described herein. 
         FIG.  25 B  is a cross-sectional view of the severing restraint of  FIG.  25 A  taken along line 25B-25B in  FIG.  25 A . 
         FIG.  25 C  is an enlarged cross-sectional view of the severing restraint of  FIG.  25 A  taken along line  25 C– 25 C coextensive with axis  253  in  FIG.  25 A . 
         FIG.  25 D  is a side view depicting the severing restraint of  FIG.  25 A  in position on a larger shrimp. 
         FIG.  25 E  is a side view depicting the severing restraint of  FIG.  25 A  in position in a smaller shrimp to illustrate the effect of the beveled surface of the notch on larger and smaller shrimp as discussed herein. 
         FIG.  26    is a perspective view of one illustrative embodiment of a measurement module that may be used in one or more embodiments of a shrimp processing system as described herein. 
         FIG.  27    is an enlarged view of a portion of the measurement module depicted in  FIG.  26   . 
         FIG.  28    is a perspective view of one illustrative embodiment of a measurement module that may be used in one or more embodiments of a shrimp processing system as described herein. 
         FIG.  29    is an enlarged view of a portion of the measurement module depicted in  FIG.  28   . 
         FIG.  30    depicts the measurement module of  FIGS.  26 - 29    in a view illustrating the distribution of energy between an emitter and receiver in the depicted illustrative embodiment of a measurement module used in a shrimp processing system as described herein. 
         FIGS.  31 - 33    depict stages in one illustrative embodiment of heading of a shrimp as described herein. 
         FIG.  34    is a schematic block diagram of components in one illustrative embodiment of a shrimp heading apparatus as described herein. 
         FIG.  35    is a perspective view of one illustrative embodiment of a shrimp heading apparatus as described herein. 
         FIGS.  36 - 37    are enlarged views of portions of the shrimp heading apparatus depicted in  FIG.  35   . 
         FIG.  38    is an opposite side perspective view of the shrimp heading apparatus of  FIG.  35    with a portion of the shuttle removed to expose components located within the shuttle of the shrimp heading apparatus. 
         FIGS.  39 - 41    depict one illustrative embodiment of a heading restraint that may be used in one or more embodiments of a shrimp heading apparatus as described herein. 
         FIG.  42    is an enlarged view of one illustrative embodiment of a spoon used in one or more embodiments of a heading apparatus as described herein. 
         FIG.  43    is an enlarged view of a portion of the spoon depicted in  FIG.  42    located within a guide on a heading restraint used in one or more embodiments of a heading apparatus as described herein. 
         FIGS.  44 - 45    depict one illustrative embodiment of a heading apparatus in use to identify the location of a carapace junction on a shrimp as part of a heading process as described herein. 
         FIGS.  46 - 47    depict one illustrative embodiment of a heading apparatus in use to remove the carapace from a shrimp as a part of a heading process as described herein. 
         FIGS.  48 - 49    depict one illustrative embodiment of a damped actuator that may be used to move one or more embodiments of a spoon in one or more embodiments of a heading apparatus as described herein. 
         FIG.  49 A  is a perspective view of a portion of the damped actuator of actuator of  FIGS.  48 - 49   . 
         FIG.  50    depicts a variety of shrimp after a heading process. 
         FIGS.  51 - 52    are schematic diagrams of one illustrative embodiment of a peeling apparatus that may be used in one or more embodiments of a shrimp processing system as described herein. 
         FIG.  53    is a schematic block diagram of a control system that may be used in one illustrative embodiment of a peeling apparatus that may be used in one or more embodiments of a shrimp processing system as described herein. 
         FIG.  54 A  is a perspective view of one illustrative embodiment of a peeling apparatus as described herein. 
         FIG.  54 B  is a side view of the illustrative embodiment of a peeling apparatus of  FIG.  54 A , with the upper and lower roller assemblies in the operating position as described herein. 
         FIG.  54 C  is a side view of the illustrative embodiment of a peeling apparatus of  FIG.  54 A , with the upper and lower roller assemblies in the receiving position as described herein. 
         FIG.  54 D  is an enlarged perspective view of a portion of the peeling apparatus depicted in  FIG.  54 A . 
         FIG.  55 A  is a perspective view of another illustrative embodiment of a peeling apparatus as described herein with the upper and lower roller assemblies in the receiving position as described herein. 
         FIG.  55 B  is a perspective view of the peeling apparatus of  FIG.  55 A , with the upper and lower roller assemblies in the operating position as described herein. 
         FIG.  55 C  is an enlarged side view of the peeling apparatus of  FIG.  55 B , the view depicting the relationship between the clamp, working surface and lower rollers of this illustrative embodiment. 
         FIG.  55 D  is a further enlarged view of a portion of the peeling apparatus depicted in  FIG.  55 C . 
         FIG.  56    is a schematic diagram illustrating the relationship between one illustrative embodiment of a lower roller assembly, as well as rotation of the rollers in the lower roller assembly in one or more embodiments of a peeling apparatus as described herein. 
         FIG.  57    is a schematic diagram illustrating one illustrative embodiment of a pair of upper rollers that may be used in one or more embodiments of a peeling apparatus as described herein. 
         FIG.  58    is a schematic diagram of the upper rollers of  FIG.  57    taken along their respective axes. 
         FIG.  59    is a schematic diagram depicting one illustrative embodiment of an alternative peeling apparatus configured to remove the pleopods and pereiopods from the ventral surface of the abdomen of shrimp while leaving the shell segments on the dorsal surface intact. 
         FIG.  60    is a perspective view of one illustrative embodiment of a shell segment separator apparatus that may be used in one or more embodiments of a shrimp processing system as described herein. 
         FIG.  61    is a schematic block diagram of a control system that may be used in one illustrative embodiment of a shell segment separator apparatus that may be used in one or more embodiments of a shrimp processing system as described herein. 
         FIGS.  62  and  63    are enlarged perspective views of the shell segment separator apparatus of  FIG.  60    with the first and second shell segment retainers in the ready configuration. 
         FIG.  64    is an enlarged perspective view of the shell segment separator apparatus of  FIG.  63    with the first and second shell segment retainers in the retention configuration. 
         FIG.  65    is a side view of the shell segment separator apparatus of  FIG.  64   , with the second shell segment retainer in the initial position. 
         FIG.  66    is a side view of the shell segment separator apparatus of  FIG.  64    after the second shell segment retainer has been moved from the initial position to the separation position. 
         FIG.  67    depicts another illustrative embodiment of a shell segment separator apparatus that may be used in one or more embodiments of a shrimp processing system as described herein in which the depicted shell segment retainer is in the ready configuration, the view being taken along a processing axis passing through the shell segment separator apparatus. 
         FIG.  68    depicts the shell segment separator apparatus of  FIG.  67    with the depicted shell segment retainer in the retention configuration. 
         FIG.  69    is a cross-sectional view of the shell segment separator apparatus of  FIG.  68    taken along line 69-69 in  FIG.  68    with the first and second shell segment retainers in an initial position. 
         FIG.  70    is a view of the shell segment separator apparatus of  FIG.  69    with the first and second shell segment retainers moved to a separation position. 
     
    
    
     While the above-identified figures (which may or may not be drawn to scale) set forth embodiments of the invention, other embodiments are also contemplated, as noted in the discussion. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope of this invention. 
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     In the following description, reference is made to the accompanying figures of the drawing which form a part hereof, and in which are shown, by way of illustration, specific embodiments. It is to be understood that other embodiments may be utilized and changes may be made without departing from the scope of the present invention. 
       FIG.  1 A  is a block diagram of one illustrative embodiment of a modular shrimp processing system as described herein. The shrimp processing system includes a series of stations at which one or more functions may be performed. In the depicted illustrative embodiment, the left most station L may be described as a loading station in which shrimp  2  are loaded onto clamps  12  such that each shrimp  2  can be retained and processed by the depicted shrimp processing system. 
     In the depicted embodiment, a plurality of clamps  12  are provided on a clamp mount  10 . In one or more alternative embodiments, however, each clamp  12  may be individually moved through a shrimp processing system as described herein, i.e., the clamp mount  10  carrying a plurality of clamps  12  is optional. 
       FIG.  1 A  also depicts a conveying system  15  used to move the clamp mounts  10  through the shrimp processing system. In the depicted embodiment, conveying system  15  uses a pair of conveying elements  17  to which clamp mounts  10  are attached which can be used to move the clamp mounts  10  through the groups of processing stations to process shrimp loaded on the clamps. The conveying elements  17  may be in the form of, for example, belts, chains, etc. as used in any suitable conventional conveying equipment. Although the depicted embodiment of conveying system  15  includes to conveying elements  17 , other embodiments of conveying systems used in shrimp processing systems as described herein may include only one conveying element or three or more conveying elements as needed to move clamps  12  through the shrimp processing system. 
     The shrimp processing system further includes a series of groups P1, P2, P3 of processing stations  16  at which one or more processes may be performed on each shrimp  2  loaded onto clamps  12  as the shrimp pass through the processing system. It may be preferred that the number of processing stations  16  in each group P1, P2, P3 match the number of clamps  12  provided on each clamp mount  10  (which, in the depicted embodiment, includes four clamps  12  and four processing stations  16  in each group), although this is not necessary in all embodiments of shrimp processing systems as described herein. 
     The conveying system  15  may, in one or more embodiments, deliver or move clamps  12  into selected locations in each of the processing stations  16  such that the equipment at each of the processing stations  16  can be operated based on having clamps  12  carrying shrimp  2  at those selected locations. Each successive clamp  12  is moved into each selected location in the processing stations  16  to assist the processing stations in accurately processing shrimp held in the clamps  12 . Moving clamps  12  carrying shrimp into selected locations in the processing stations  16  can be distinguished from shrimp processing systems and methods in which shrimp are moved through a shrimp processing system without control over the location of the shrimp (for example, systems in which shrimp are entrained in water, etc.). As discussed herein, for example, many of the processing stations  16  are designed to act on specific features found in the shrimp in the clamps  12  and accurately locating those features as successive shrimp are moved into each selected location assists in effective and efficient processing of shrimp using the shrimp processing systems described herein. 
     An unloading station U is located after the groups P1, P2, P3 of processing stations at which shrimp  2  may be unloaded/released from the clamps  12  on each clamp mount  10  after passing through the groups P1, P2, P3 of processing stations. 
     The illustrative embodiment of the shrimp processing system depicted in  FIG.  1 A  also includes an optional sorting station S at which shrimp  2  may be separated into bins or other containers  18  based on one or more characteristics such as, e.g., weight, length, shelled, unshelled, etc. 
     In the depicted embodiment, the conveying system  15  advances the clamps  12  from the loading end L to the unloading station U. In one or more embodiments, the conveying system may include ejection stations at the unloading station U that are configured to eject shrimp from the clamps  12 . In one or more embodiments, the ejection stations may be a set of plungers acting on shrimp  2  located in clamps  12 . 
       FIGS.  1 B and  1 C  depict one illustrative embodiment of a set of plungers in one illustrative embodiment of an unloading station U that may be used to eject or remove shrimp  2  from clamps  12  that, as discussed herein, may be carried on a clamp mount  10  using conveying elements  17 . The plungers  13  are mounted to force shrimp  2  out of clamps  12  using an actuator  19  (e.g., a piston operated hydraulically, pneumatically, using a solenoid, etc.). The actuator  19  is retracted in  FIG.  1 B  as the shrimp  2  carried in clamps  12  are moved into position. When the shrimp  2  are in position on the plungers  13 , the actuators  19  may be actuated to force the shrimp  2  out of the clamps  12  as depicted in, e.g.,  FIG.  1 C . In the depicted illustrative embodiment, the plungers  13  may be described as having arcuate surfaces that act on the ventral surfaces of the shrimp  2  to, preferably, reduce or eliminate damage to the shrimp  2  during the unloading/ejection process. In one or more embodiments, the actuators  19  may be operably connected to a control system used to operate the conveying system  15  and/or any other apparatus used in the shrimp processing systems described herein. 
     With reference to  FIG.  2   , one illustrative embodiment of a control system used to control operation of a shrimp processing system as described herein is depicted. The control system includes a controller  90  that is operably connected to processing stations of a shrimp processing system. The depicted illustrative shrimp processing system includes a processing station for measuring  93 , a processing station for severing mud veins  94 , a processing station for heading shrimp  95 , a processing station for peeling shrimp  96  (where peeling may include removing abdominal shell segments on the dorsal surface along with removing pleopods and pereiopods from the ventral surface, or removing the pleopods and pereiopods from the ventral surface while leaving the shell segments on the dorsal surface intact), a processing station for separating adjacent abdominal shell segments on shrimp  97 , and an ejection/sorting station  98 . The shrimp processing system also includes a conveying system  92  operably connected to the controller as well as being operably connected to each of the processing stations to move clamps carrying shrimp through the various processing stations as described herein. 
     Although the controller  90  depicted in connection with the illustrative embodiment of a shrimp processing system of  FIG.  2    is in the form of a single controller in which all control functions may be performed by a single controller (although backup and/or redundant controllers may be provided to assist in the case of failure of a primary controller), one or more alternative embodiments of shrimp processing systems may include a distributed set of controllers, with those processing stations requiring a controller having a dedicated controller and, potentially, a network may be used to interconnect the various controllers to facilitate processing of shrimp by the shrimp processing system. 
     The controllers used in one or more embodiments of shrimp processing systems as described herein may be provided in any suitable form and may, for example, include memory and a controller. The controller may, for example, be in the form of one or more microprocessors, Field-Programmable Gate Arrays (FPGA), Digital Signal Processors (DSP), microcontrollers, Application Specific Integrated Circuit (ASIC) state machines, etc. The controllers may include one or more of any suitable input devices configured to allow a user to operate the apparatus (e.g., keyboards, touchscreens, mice, trackballs, etc.), as well as display devices configured to convey information to a user (e.g., monitors (which may or may not be touchscreens), indicator lights, etc.). 
     Although depicted as being separate in  FIG.  2   , it should be understood that one or more processing stations may be combined in one or more embodiments of shrimp processing systems as described herein. For example, group P1 of processing stations in the shrimp processing system depicted in  FIG.  1 A  may be configured to both measure shrimp  2  and sever the mud veins of the shrimp  2  restrained on clamps  12  in each of the processing stations  16  in that group (thus performing both functions described for processing stations  93  and  94  in the system as depicted in  FIG.  2   ). Other combinations of processing steps may also be incorporated into single processing stations. 
     Furthermore, some processes such as, e.g., measuring, may be performed more than once on each shrimp. For example, in one or more embodiments, shrimp may be measured as a part of the process for severing the mud veins in shrimp passing through the shrimp processing system and may be measured again to assist with other processing such as, e.g., heading, sorting, shell segment separation, etc. 
     Although all of the different shrimp processing apparatus described herein may preferably be incorporated into a single shrimp processing system or method, it should be understood that any single apparatus described herein may be used in a standalone configuration in which only the functions performed by a specific apparatus are performed on each shrimp passing through that apparatus or method. For example, a single station may be provided for heading shrimp that is not preceded by a mud vein severing apparatus or measurement apparatus or method. Similarly, a single station may be provided for peeling shrimp that have not been processed by a heading apparatus or that have had their heads removed by another process or apparatus before being delivered to a peeling apparatus as described herein. 
     Further, any two or more of the different shrimp processing apparatus described herein may be incorporated into the shrimp processing systems and methods as described herein. For example, a shrimp processing system or method as described herein may include a measurement apparatus and a mud vein severing apparatus, with the measurement apparatus and the mud vein severing apparatus being provided as either separate processing stations in the shrimp processing system or combined in an integrated processing station of a shrimp processing system. 
     In another variation, a shrimp processing system or method as described herein may include a measurement apparatus and a shell segment separator apparatus as described herein, with the measurement apparatus and the shell segment separation apparatus provided as either separate processing stations in the shrimp processing system or combined in an integrated processing station of a shrimp processing system. 
     In another variation, a shrimp processing system or method as described herein may include a measurement apparatus and a heading apparatus as described herein, with the measurement apparatus and the heading apparatus provided either as separate processing stations in the shrimp processing system or combined in an integrated processing station of a shrimp processing system. 
     The methods of processing shrimp as described herein, whether used with the processing systems described herein or not, may include loading individual shrimp into each clamp of a plurality of clamps to provide a plurality of loaded clamps, with each loaded clamp restraining only one individual shrimp at a time. The method may further include transporting each loaded clamp carrying a shrimp between a plurality of processing stations using a conveying system that connects the processing stations. In one or more methods, the method may include collecting data on each shrimp in the loaded clamps in at least one processing station of the plurality of processing stations. In one or more methods, the method may include performing one or more actions on each shrimp in the plurality of loaded clamps in at least one processing station of the plurality of processing stations. 
     In one or more embodiments of the methods described herein, the clamps may be arranged in groups of two or more clamps on the conveying system, wherein transporting each loaded clamp between the plurality of processing stations includes simultaneously transporting the groups of two or more clamps between the plurality of processing stations. 
     In methods in which the processing stations are arranged in groups of two or more processing stations, the methods described herein may include transporting the groups of two or more loaded clamps between the groups of two or more processing stations, and collecting data on the shrimp in each group of the two or more clamps at each group of two or more processing stations configured to collect data before transporting each group of two or more clamps out of the group of two or more processing stations. Further, the method may include performing one or more actions on the shrimp in each group of two or more clamps at each group of two or more processing stations configured to perform one or more of the actions before transporting each group of two or more clamps out of the group of two or more processing stations configured to perform the one or more actions. 
     In one or more methods of processing shrimp as described herein, collecting data may include measuring a length of each shrimp when, for example, each shrimp is located in a clamp as described herein. In one or more embodiments of the methods described herein a weight may be assigned to each shrimp based at least in part on the length of each shrimp as measured in one or more methods as described herein. 
     One or more methods of processing shrimp as described herein may include performing actions such as, for example, severing a mud vein in each shrimp at a selected location on the shrimp. In one or more embodiments, the method may include identifying the selected location at which the mud vein is to be severed based at least in part on the length of each shrimp as measured in one or more methods of processing shrimp as described herein. 
     One or more of methods of processing shrimp as described herein may include removing a head from each shrimp, with the head optionally being removed after severing a mud vein on each shrimp proximate a tail of the shrimp. Removal of the head according to one or more methods of processing shrimp as described herein may include identifying a carapace junction between the carapace and the abdomen of each shrimp before removing the head from each shrimp. 
     One or more methods of processing shrimp as described herein may include separating adjacent abdominal shell segments found on the dorsal surface of the abdomen of shrimp before removing the abdominal shell segments from the shrimp. 
     One or more methods of processing shrimp as described herein may include simultaneously removing abdominal shell segments along with one or more pleopods from each shrimp. One or more methods of processing shrimp as described herein may include removing one or more pleopods from each shrimp while leaving the abdominal shell segments intact. 
     Illustrative examples of shrimp processing systems and methods of processing shrimp are presented below in connection with a variety of illustrative examples of shrimp processing stations and the methods performed at those stations. It should be understood that the processing stations and the methods performed at those stations are only illustrative examples of processing stations and methods that may be used in a processing system as described herein in connection with  FIGS.  1 - 2    and that other alternative processing stations and methods may be used in a shrimp processing system as described herein. 
     To assist with discussion of the shrimp processing stations and methods performed at them, one example of a shrimp that may be processed using the shrimp processing systems and methods described herein is depicted in  FIG.  3    along with a description of the various anatomical features of the shrimp. The depicted shrimp  102  includes an abdomen  104  terminating in a tail/uropod  106  (although the proper name for this anatomical feature is the uropod, for simplicity it will be referred to simply as the “tail” herein). An appendage referred to as the telson  107  sits above the dorsal surface of the tail  106 . Although the depicted shrimp  102  includes an abdomen  104  having six segments, other shrimp that may be processed using shrimp processing systems as described herein may have more or fewer segments forming the abdomen of the shrimp. 
     The head or carapace  108  of the shrimp  102  is attached to the abdomen  104  at the opposite end from the tail  106 . The carapace  108  contains the viscera of the shrimp  102  and also carries various features such as antennae, rostrum, etc. Removal of the head or carapace  108  using the processing systems and methods described herein results in removal of the features attached directly to the carapace  108 . 
     The shrimp  102  also includes appendages in the form of pleopods  105  (sometimes referred to as swimmerets) attached to the ventral side of the abdomen  104 . Additional appendages  109  are also attached to the ventral side of the shrimp  102  forward of the abdomen  104 , i.e., the ventral side of the carapace  108 . Those appendages  109  may include, for example, the pereiopods (sometimes referred to as “walking legs”) and chela. Removal of the head or carapace  108  using the processing systems and methods described herein typically results in removal of at least some of the appendages  109  attached to the ventral side of the carapace  108 . 
     The abdomen  104  includes six segments located between the carapace  108  and the tail/uropod  106  and telson  107 . The segments are numbered starting at the carapace  108  and proceeding towards the tail  106 , with the abdominal segment closest to the carapace  108  being referred to as the first segment and the abdominal segment closest to the tail 106/telson  107  being referred to as the sixth segment. Each abdominal segment includes a shell segment on the dorsal side of the abdomen. 
     The shrimp processing systems and methods described herein rely on processing of individual shrimp being retained and moved through the systems for individual processing. In one or more embodiments, each shrimp may be retained proximate its tail/uropod using a clamp, although other locations for restraining shrimp for processing in the shrimp processing systems and methods described herein are also contemplated. 
     Shrimp Processing System Clamps and Methods 
       FIGS.  4 - 6    depict one illustrative embodiment of a clamp that may be used in one or more illustrative embodiments of shrimp processing systems and methods described herein. The clamp  112  is configured to capture and retain a shrimp proximate the tail. The depicted embodiment of clamp  112  is only one example of a clamp that may be used to capture and retain shrimp processed in the shrimp processing systems and methods described herein. 
     The illustrative embodiment of clamp  112  is located on a base  110  (see, e.g.,  FIG.  5   ). Although the base  110  is shown as being separate and distinct from the clamp  112 , in one or more embodiments, the base  110  may form an integral part of the clamp  112 . 
     The clamp  112  includes a body  120  attached to the base  110  along with a pair of arms  122  extending away from the body  120  with arms  122  connecting a pair of jaws  124  to the body  120  through arms  122 . Each of the jaws  124  includes a jaw face  125  with the jaw faces  125  on the opposing jaws  124  facing each other along a clamping axis  121  that extends between the jaws  124 . 
     The jaw faces  125  on each of the jaws  124  define a receiving slot between the jaw faces  125 . In one or more embodiments, a distance between the jaw faces  125  across the receiving slot in a direction aligned with the clamping axis  121  narrows when moving away from the base  110  between the jaw faces  125  along a compression axis  123 , with the compression axis  123  extending through the base  110  between the jaw faces  125  (in other words, through the receiving slot between the jaw faces  125 ). 
     In the depicted illustrative embodiment of clamp  112 , one or both of the arms  122  connecting each of the jaws  124  to the body  120  function as a spring member operably attaching the jaws  124  to the body  120 . In one or more embodiments, one or both of the spring members/arms  122  resists movement of the attached jaw  124  away from the opposing jaw along the clamping axis  121 . In one or more embodiments, one or both of the spring members/arms  122  also resists movement of the attached jaw  124  away from the base  110  along the compression direction aligned with the compression axis  123 . As a result, a shrimp located in the receiving slot between the jaw faces  125  of jaws  124  is compressed against the base  110  by one or both of the jaws  124 . 
     With reference to  FIG.  6   , the distance between the body  120  and the receiving slot defined between the faces  125  of jaws  124  in a direction transverse to both the clamping axis  121  and the compression axis  123  may be selected to allow the tail  106  of a shrimp captured in the clamp  112  to be positioned between the receiving slot and the body  120  of the clamp  112 . In one or more embodiments, the distance between the body  120  and the receiving slot may be 4 or more, 6 or more, 8 or more, 10 or more, 12 or more, 14 or more, 16 or more, 18 or more, or 20 or more times the receiving slot width measured at a midpoint between the base  110  and the narrowest portion of the receiving slot as measured along a direction aligned with the clamping axis  123 . In one or more embodiments, the distance between the body  120  and the receiving slot may be 24 or less, 22 or less, 20 or less, 18 or less, or 16 or less times the receiving slot width measured at the midpoint between the base  110  and the narrowest portion of the receiving slot as measured along a direction aligned with the clamping axis  123 . 
     Again, with reference to  FIG.  6   , the compression force along compression axis  123  may, in addition to assisting and retaining the shrimp in position in clamp  112 , also force the base of the tail  106  of the shrimp against the base  110  on which clamp  112  is located. That action may, in one or more embodiments, force the tail  106  of the shrimp to fan out or splay as seen in  FIG.  6   . As a result, the leading edges of the tail  106 , when splayed, may act against the jaws  124  of clamp  112  to further assist in resisting removal of the shrimp from the clamp  112  in a direction transverse to both the clamping axis  121  and the compression axis  123 . 
     Another optional feature depicted in connection with clamp  112  is found in the standoffs  126  on each of the jaws  124 . Raising the jaws  124  off the base  110  may, in one or more embodiments, provide clearance between the arms  122  and the base  110  such that the jaws  124  are able to rotate about rotation axes  127  extending through the arms  122  that extend from the jaws  124  to the body  120  (see, for example, the rotation axes  127  depicted in FIG. 
     4). Rotation of the jaws  124  about the rotation axes  127  may, in one or more embodiments, keep a center of pressure imposed on shrimp of different sizes by the jaws  124  above a centerline at which the jaws  124  of the clamp  112  contact the differently sized shrimp. 
     It should be understood that rotation of the jaws  124  may occur even in the absence of standoffs  126 . Further, it should be understood that although both the jaws  124  in the depicted embodiment of clamp  112  may rotate about their respective rotation axes  127 , in one or more embodiments, only one of the jaws  124  may be configured to rotate about a rotation axis  127 . 
     In one or more embodiments of clamps for restraining shrimp as described herein, the clamp  112  may be constructed of a polymeric material providing sufficient strength and resilience to form both the arms  122  as well as the jaws  124  in a manner that provides the functions described herein for clamp  112 . Alternatively, the clamp  112  may be constructed of a variety of components assembled together to provide the various features and their functions of a clamp capable of restraining a shrimp as described herein. For example, arms  124  could be formed of spring steel or some other resilient material that is different from the material used for the body  120  and/or the jaws  124  of the clamp  112 . Other variations such as, e.g., an over molded spring-steel mechanism, will also be known to those of skill in the art. 
     In one or more embodiments of methods of restraining shrimp as described herein, the method may include providing a clamp having first and second jaws positioned on a base, with the jaws defining a receiving slot therebetween, inserting a shrimp into the receiving slot such that the tail of the shrimp is located on a clamp side of the jaws and the carapace of the shrimp is located on a processing side of the jaws. Although not required, the method may, in one or more embodiments, further include forcing the tail of the shrimp towards the base such that the tail forms a splayed tail fan on the clamp side of the jaws. 
     Described with respect to the illustrative embodiment of clamp  112 , the method may include providing clamp  112  having first and second jaws  124  on base  110 . The jaws  124  define a receiving slot therebetween. Inserting a shrimp into the receiving slot such that the tail of the shrimp  106  is located on a clamp side of the jaws  124  (in other words, the side of the jaws  124  facing the body  120  of clamp  112 ) while the carapace of the shrimp is located on a processing side of the jaws  124  (in other words, the side of the jaws  124  facing away from the body  120  of the clamp  112 ). In the depicted embodiment, the abdomen  104  of the shrimp is also located on the processing side of the jaws  124  because the jaws  124  act against the shrimp at the junction between the tail  106  and the abdomen  104 . In one or more embodiments, the jaws  124 , along with the spring members/arms  122  act to force the shrimp towards or against the base  110  such that the tail forms a splayed tail fan on the clamp side of the jaws  124 . A splayed tail fan may further resist removal of the shrimp from the clamp  112  in a direction transverse to both the clamping axis  121  and the compression axis  123 . 
     In one or more embodiments of the methods of restraining a shrimp in a clamp as described herein, the compressive force on the shrimp towards the base along the compression axis  123  may be described as a persistent compressive force. In other words, the force may be present as long as the shrimp is retained in the clamp. The compressive force provided by the clamp may, in one or more embodiments, be assisted when the jaws of the clamp widen when approaching the base on which the clamp is positioned (or narrow when moving away from the base on which the clamp is positioned) because the force vectors applied to the shrimp by angled faces of the jaws of the clamp may assist in providing a compressive force to the shrimp as described herein by virtue of their shape. 
     Moreover, one or more embodiments of the methods of restraining shrimp in a clamp as described herein may involve rotation of one or both of the jaws of the clamp as discussed above in connection with the illustrative embodiment of clamp  112 . In particular, the clamp  112  includes a body  120  and a first jaw  124  connected to the body  120  through a first arm  122  as well as a second jaw  124  connected to the body  120  through a second arm  122 . One or both of the jaws  124  may, in one or more embodiments, rotate about a rotation axis  127  located above the base  110  and extending between the rotating jaw  124  and the body  120  when inserting a shrimp into the receiving slot formed between the first and second jaws  124 . 
       FIG.  7    is a perspective view of a set of clamps  112  that may be used in one or more embodiments of a shrimp processing system as described herein. The group of clamps  112  may be described as being attached to a clamp mount  110 , with a plurality of the clamp mounts  110  being attached to conveying elements  117  of a conveying system used to move the clamps  112  mounted on the clamp mounts  110  through a shrimp processing system as described herein. In the depicted embodiment, conveying elements  117  are in the form of belts that may be driven by any suitable mechanism to move the clamp mounts  110  and clamps  112  located thereon through a shrimp processing system as described herein. 
     Although the depicted illustrative embodiments of clamp mounts  110  carry four clamps  112 , it should be understood that clamp mounts  110  may carry only one clamp, two clamps, three clamps or five or more clamps depending on the number of processing stations in a given shrimp processing system. Further, although  FIG.  7    depicts to conveying elements  117 , it should be understood that a conveying system used to advance clamps  112  and any clamp mounts  110  through a shrimp processing system as described herein may include as few as one conveying element or three or more conveying elements depending on the specific design of the conveying system. 
     Further, although the conveying elements  117  are in the form of belts, it should be understood that conveying elements used in shrimp processing systems as described herein may take any of a variety of forms common to conveying systems including, but not limited to, belts, chains, etc. 
     In the depicted illustrative embodiment, the conveying elements  117  carry mounting bosses  132  with each of the clamp mounts  110  including corresponding mounting blocks  130 , with each block  130  configured to attach to a mounting boss  132  on the conveying elements  117 . The blocks  130  may attached to the mounting bosses  132  by any suitable technique or combination of techniques including, for example, mechanical fasteners, adhesives, clamps, interference fits, mechanical interlocks, etc. 
     Referring to  FIGS.  8 - 10   , one illustrative embodiment of a set of mounting bosses  132  and blocks  130  used to attach a clamp mount  110  to a conveying element  117  is depicted in more detail. In the depicted illustrative embodiment, the mounting bosses  132  and blocks  130  are attached to each other using magnetic attraction. In particular, each of the mounting bosses and blocks carry permanent magnets to retain the blocks  130  on the mounting bosses  132  which, in turn, retains the clamp mounts  110  on the conveying elements  117  for movement through a shrimp processing system as described herein. 
     With reference to  FIGS.  8 - 9   , the mounting blocks  130  (which are shown as transparent to allow visualization of the components contained therein) is attached to the clamp mount  110  using, in the depicted embodiment, a pair of mechanical fasteners. The mounting block also includes a pair of magnets  134  positioned above a mating feature  136  formed in clamp mount  110 . 
     The mating feature  136  is designed to mate with a complementary mating feature  137  on mounting boss  132  to assist in both alignment and retention of the clamp mount  110  to the mounting boss  132  on conveying element  117 . Although mating feature  136  is depicted in the form of a recess/well/aperture and complementary mating feature  137  on mounting boss  132  is depicted in the form of a protrusion, it will be understood that any pair of complementary mating features found on the clamp mount  110  and the mounting boss  132  may provide the same functionality as the illustrative pair of complementary mating features depicted in  FIGS.  8 - 9   . 
     With reference to  FIG.  10   , which is a cross-sectional view of the clamp mount  10 , mounting boss  132 , and mounting block  130  taken along line 10-10 in  FIG.  9   , it can be seen that, in the depicted illustrative embodiment, the mounting boss  132  includes a complementary pair of magnets  135  positioned to magnetically attract magnets  134  in mounting block  130  attached to the clamp mount  110 . It may be preferred that pairs of magnets  134  and  135  be provided in both the mounting block  130  and the mounting boss  132  such that the magnets  134  and  135  form close magnetic fields to reduce the likelihood that magnetic fields associated with the mounting blocks  130  and mounting bosses  132  can affect any electrical or magnetic components of a shrimp processing system as described herein. The relationship between the complementary mating features  136  and  137  on the clamp mount  110  and mounting boss  132  can also be seen in the cross-sectional view of  FIG.  10   . 
     The use of magnets and complementary mating features as seen in  FIGS.  8 - 10    may, in one or more embodiments, provide a relatively easy to clean connection system for retaining clamp mounts  110  in position on conveying elements  117  of shrimp processing systems as described herein. Many other structures and/or techniques of retaining clamp mounts on conveying elements of a conveying system will, however, be understood as being suitable for use in place of the depicted illustrative embodiment of mounting blocks  130 , clamp mounts  110  and mounting bosses  132  described in connection with  FIGS.  8 - 10   . 
     With reference to  FIGS.  7  and  11   , another optional feature of one or more embodiments of a shrimp processing system as described herein can be seen in the offset between the conveying elements  117  and the clamps  112  used to retain and move shrimp through a processing system. In particular,  FIG.  11    depicts a pair of shrimp  102  retained in clamps  112  attached to a clamp mount  110  that is moved along a processing direction  101  using conveying element  117 . Shrimp  102  are supported during movement along the processing direction  101  by working surfaces  114  which are located on opposite sides of conveying element  117 . Those working surfaces are able to support shrimp  102  retained in clamps  112  because the conveying elements  117  are not aligned with the clamps  112  along the processing direction  101 . 
     Supporting restrained shrimp on working surfaces  114  that are separate and different from the conveying elements  117  may, in one or more embodiments, provide the ability to improve cleanliness and hygiene of a shrimp processing system because the working surfaces  114  may be separately cleaned and/or replaced during use to limit contamination and improve hygiene. 
     Although one illustrative embodiment of clamps that can be used to restrain shrimp as described herein within a shrimp processing system is depicted in the preceding figures, it should be understood that other alternative clamps can be used to provide for restraint and movement of shrimp in processing systems as described herein. One illustrative embodiment of an alternative clamp  112 ′ that may be used in one or more shrimp processing systems as described herein is depicted in  FIGS.  12 - 13   . The clamp  112 ′ includes jaws  124 ′ mounted on a body  120 ′ that are spring-loaded to move towards each other. The shape and spring-loaded mounting of jaws  124 ′ provide for a clamping force along a clamping axis  121 ′ and, preferably, a compression force along a compression axis  123 ′ extending through the receiving slot located between opposing jaws  124 ′. 
     With reference to  FIG.  13   , the clamps  112 ′ may also be provided on a clamp mount  110 ′ for movement through a conveying system using a conveying element  117 ′ that is offset from clamps  112 ′ such that shrimp  102 ′ can be supported on a working surface  114 ′ that is offset from the conveying element  117 ′. 
     Another alternative illustrative embodiment of clamps  112 ″ is depicted in  FIG.  14    with clamps  112 ″ being carried on a clamp mount  110 ″. Each of the clamps  112 ″ is depicted as restraining a shrimp  102 ″ on a working surface  114 ″, while the clamp mount  110 ″ carrying clamps  112 ″ is moved through a processing system using conveying element  117 ″ positioned between the working surfaces  114 ″. Clamps  112 ″ include spring elements  122 ″ used to provide pressure on the shrimp  102 ″ to retain the shrimp  102 ″ in the clamps  112 ″. 
     It should be understood that  FIGS.  12 - 14    depict only two alternative illustrative embodiments of clamps that may be used to retain shrimp in a processing system for processing according to the methods described herein. Many other clamps may be used to restrain shrimp for processing in the systems and methods described herein. 
     Measuring and Mud Vein Severing Apparatus &amp; Methods 
     Among the processing stations that may be found in one or more embodiments of shrimp processing systems as described herein are stations that may be used to measure shrimp and stations that may be used to sever the mud vein of shrimp. In one or more embodiments, the same processing station may be used to both measure shrimp and sever the mud vein of shrimp. 
       FIG.  15    is a schematic block diagram depicting components that may be found in one such system configured to both measure shrimp and sever the mud vein in the shrimp. The depicted station includes a measurement module  260  and a vein severing module  270  along with a controller  290  and conveying system  292 . 
     The measurement module  260  may preferably be a noncontact measurement module that is configured to measure shrimp without requiring physical contact with the shrimp. In one or more embodiments, the measurement module  260  may include an emitter  262  and a receiver  264  that, together, emit and receive energy such as, e.g., optical energy, ultrasonic energy, etc. Although depicted separately, the emitter  262  and receiver  264  may be combined in a transceiver that relies on reflected energy to measure shrimp. 
     The vein severing module  270  may include a variety of components including a severing module drive  271 , a severing restraint actuator  252  (operably connected to a severing restraint), and a blade actuator  245  (operably connected to a blade). The severing module drive  271 , severing restraint actuator  252 , and blade actuator  245  may each be connected to the controller  292  control movement of the vein severing module  270 , the severing restraint actuator  252 , and the blade actuator  245 . 
     Control over the conveying system  292  by the controller  290  may be used to move shrimp into and out of the measurement module  260  and/or the vein severing module  270 . 
     Although the controller  290  depicted in connection with the illustrative embodiment of a shrimp measurement and mud vein severing apparatus as depicted in  FIG.  15    is in the form of a single controller in which all control functions may be performed by a single controller (although backup and/or redundant controllers may be provided to assist in the case of failure of a primary controller), one or more alternative embodiments of shrimp measurement and mud vein severing apparatus may include a distributed set of controllers, with those portions of the apparatus requiring a controller having a dedicated controller and, potentially, a network may be used to interconnect the various controllers to facilitate processing of shrimp by the measurement and mud vein severing apparatus. Further, the controller  290  (or any other controllers used in a mud vein severing apparatus as described herein) may be separate from or integrated into a system controller such as, e.g., controller  90  depicted in connection with a control system used to control a shrimp processing system as depicted in  FIG.  2   . 
     The controllers used in one or more embodiments of shrimp measurement and mud vein separating apparatus as described herein may be provided in any suitable form and may, for example, include memory and a controller. The controller may, for example, be in the form of one or more microprocessors, Field-Programmable Gate Arrays (FPGA), Digital Signal Processors (DSP), microcontrollers, Application Specific Integrated Circuit (ASIC) state machines, etc. The controllers may include one or more of any suitable input devices configured to allow a user to operate the apparatus (e.g., keyboards, touchscreens, mice, trackballs, etc.), as well as display devices configured to convey information to a user (e.g., monitors (which may or may not be touchscreens), indicator lights, etc.). 
     One illustrative embodiment of a mud vein severing apparatus  240  is depicted in  FIG.  16 - 25 E  and one illustrative embodiment of a measurement module  260  is depicted in  FIGS.  26 - 30   . Although the mud vein severing apparatus  240  and the measurement module  260  could, in one or more embodiments, be integrated into a single processing station of the groups of processing stations (e.g., group P1) described above in connection with the illustrative shrimp processing system depicted in  FIGS.  1 A and  2   , they are depicted separately in  FIGS.  16 - 30    because they can also be provided as separate processing stations. 
     The vein severing apparatus  240  of the processing station depicted in  FIGS.  16 - 23    is positioned above the working surface  214  on which shrimp  202  are located for processing. In one or more embodiments, the shrimp  202  may be restrained in a clamp  212  such that the tail  206  of the shrimp  202  is located on one side of the clamp while the remainder of the shrimp  202  is located on the opposite side of the clamp  212 . As discussed herein, the clamp  212  may be moved to a selected location relative to the vein severing apparatus  240  such that each shrimp processed by the vein severing apparatus  240  is located in the same selected position. 
     The processing station is supported above the working surface  214  (and any shrimp  202  located thereon) on a frame  242 , with the components of the processing station being located on a carriage  244  that moves along slide  243  aligned with axis  241 . The depicted embodiment of carriage  244  includes side plates extending downward from an upper portion of the carriage  244 , although many other variations in support structures may be possible. Axis  241 , along which carriage  244  moves is, in one or more embodiments, preferably aligned with processing axis  211  passing through the working surface  214 . As a result, movement of the carriage  244  along slide 243/axis  241  results in movement of the carriage  244  and its components along the processing axis  211  to facilitate positioning of the components in the processing station with one or more selected locations on a shrimp  202  positioned on the working surface  214 . 
     The vein severing module of the depicted integrated measurement and mud vein severing apparatus includes a blade assembly  248  and a blade actuator  245  configured to move the blade assembly  248  between a stored position and a severed position. More specifically, the blade assembly  248  is mounted on a blade carriage  246 , with the blade carriage  246  being moved by the blade actuator  245  to move the blade assembly  248  between its stored position and severed position. The blade actuator  245  may be in the form of a dual acting air actuator/piston, although many other mechanisms may be used to provide the reciprocating motion needed to move the blade actuator  245  and blade assembly  248  between its stored and severed positions, for example, double acting pistons, single acting pistons, spring mechanisms, hydraulic actuators, motors, magnetic drivers, etc. 
     The blade carriage  246  moves along a blade carriage axis  247  when moving the blade assembly  248  between its stored position and severed position and, as a result, the severing direction along which the blade assembly  248  moves is aligned with the blade carriage axis  247 . In one or more embodiments the severing direction/blade carriage axis  247  may be transverse to the processing direction  211 . 
     The vein severing module also includes a severing restraint  250  configured to fix a position of a shrimp  202  held in a clamp  212  on the working surface  214 . The severing restraint  250  is operably attached to a severing restraint actuator  252  that is configured to move the severing restraint  250  between a withdrawn position as seen in, for example,  FIG.  16   , and a restraint position as seen in, for example,  FIG.  17   . A shrimp  202  held in a clamp  212  in a selected severing location on working surface  214  is restrained by the severing restraint  250  when the severing restraint  250  is in the restraint position. 
     In the depicted embodiment, severing restraint actuator  252  causes severing restraint  250  to rotate about an axis  251  when moving between the withdrawn position as seen in  FIG.  16    and the restraint position as seen in  FIG.  17   . In one or more embodiments the severing restraint actuator may be in the form of a limited force single acting piston that applies a smaller downward force when moving the severing restraint  250  into the restraint position and a larger upward or retraction force when moving the severing restraint  250  from the restraint position back to the withdrawn position. The smaller downward force may be selected so that the severing restraint  250  does not unduly damage the shrimp when the severing restraint is in its restraint position. In one or more embodiments the upward or retraction force may be provided by a spring located within the severing restraint actuator  252 . 
     Although the depicted illustrative embodiment of severing restraint actuator  252  is in the form of a single acting limited force piston, many other mechanisms may be used to provide the reciprocating motion needed to move the severing restraint  250  between its withdrawn and restraint positions, for example, double acting pistons, single acting pistons, spring mechanisms, hydraulic actuators, motors, magnetic drivers, etc. 
     A sequence of operations for the mud vein severing processing station depicted in  FIG.  16    can be described with reference to  FIGS.  16 - 21   . In  FIG.  16   , a shrimp  202  restrained in a clamp  212  carried on a clamp mount  210  is moved into a selected severing location on working surface  214 . The shrimp  202 , clamp  212 , and clamp mount  210  are moved along a processing direction aligned with processing axis  211  to place the shrimp  202  in the selected severing location on working surface  214 . The blade assembly  248  on blade carriage  246  is in the stored position and the severing restraint  250  is in its withdrawn position in  FIG.  16   . 
     With the shrimp  202  in the selected severing location on working surface  214 , the severing restraint actuator  252  may be operated to move the severing restraint  250  from its withdrawn position in  FIG.  16    toward the working surface on which shrimp  202  is restrained by clamp  212  so that the severing restraint  250  is in the restraint position as seen in  FIGS.  17 - 18   . The severing restraint  250  is located between the blade assembly  248  and the clamp  212  restraining a shrimp  202  when a shrimp  202  held in the clamp  212  is in the selected severing location on working surface  214  and the severing restraint  250  is in the restraint position as seen in  FIGS.  17 - 18   . 
     When in the restraint position as depicted in  FIGS.  17 - 18   , the illustrative embodiment of severing restraint  250  is positioned on the abdomen of the shrimp  202  proximate the clamp  212  restraining the shrimp  202 . It should, however, be understood that other locations for severing restraint  250  may be possible in alternative embodiments of severing apparatus as described herein. Also seen in  FIGS.  17 - 18   , the blade assembly  248  on blade carriage  246  is in the stored position (which, in  FIG.  17    is shifted to the right along blade carriage axis  247 ). 
     With the shrimp  202  in the selected severing location on working surface  214  and the severing restraint  250  in the restraint position as seen in  FIGS.  17 - 18    to restrain a shrimp on the working surface  214 , the blade actuator  245  can be activated to move the blade assembly  248  from its stored position to its severed position as seen in  FIGS.  19 - 20   . Movement of the blade assembly  248  from its stored position to its severed position using blade actuator  245  along the severing direction aligned with blade carriage axis  247  moves the blade assembly  248  generally transverse to the processing direction aligned with processing axis  211 . During that movement, blade assembly  248  passes through the abdomen of the shrimp  202  restrained on working surface  214  by clamp  212  as well as severing restraint  250 . That movement of blade assembly  248  preferably severs the mud vein in shrimp  202 . 
     While the shrimp  202  remains in the selected severing location on working surface  214  and the severing restraint  250  remains in the restraint position as seen in  FIGS.  19 - 20   , the blade actuator  245  is preferably activated to move the blade assembly  248  from its severed position back to its stored position (as seen in, for example,  FIGS.  17 - 18   ). Movement of the blade assembly  248  from its severed position to its stored position using the blade actuator  245  while the shrimp  202  remains restrained by both the severing restraint  250  and the clamp  212  may prevent unwanted movement of the shrimp  202  during return of the blade assembly  248  to its stored position. 
     With the shrimp  202  remaining in the selected severing location on working surface  214 , the severing restraint  250  may be retracted upwardly away from the working surface  214  from its restraint position (as seen in, e.g.,  FIGS.  17 - 20   ) to its withdrawn position as seen in  FIGS.  16  and  21   . Movement of the severing restraint  250  may be accomplished using the severing restraint actuator  252  as described herein. Further, movement of the severing restraint  250  may also result in movement of the blade actuator  245 , blade carriage  246 , and blade assembly  248  away from the working surface  214  and the shrimp  202  located thereon. 
     Although the depicted embodiment of the mud vein severing apparatus  240  uses a fixed blade that is moved relative to a shrimp, one or more alternative embodiments of the mud vein severing apparatus as described herein may include rotary blades, water jets, etc. that may be used to sever the mud veins in shrimp as described herein. 
       FIG.  22    depicts one illustrative embodiment of a blade assembly  248  used in a mud vein severing apparatus as described herein. In particular, blade assembly  248  may be in the form of a blade holder  249   a  and a replaceable blade  249   b  that can be attached to blade holder  249   a . In one or more embodiments, the blade  249   b  may be in the form of a #10 scalpel blade or other conventional cutting instrument to allow for easy and quick replacement of the blade as needed.  FIGS.  23 - 24    depict the blade  249   b  in an enlarged view where can be seen that the blade  249   b  includes a cutting edge  249   c , with the blade  249   b  being attached to a holder  249   a  of the blade assembly  248 . In one or more embodiments, the cutting edge  249   c  of the blade  249   b  faces upwards or away from the ventral side of a shrimp in the selected severing location as the blade moves along the severing path. 
     In the depicted illustrative embodiment, the cutting edge  249   c  of the blade  249   b  is a curved edge. The curved edge of the blade  249   b  may reduce the likelihood of fracture of the blade during use in severing the mud veins of shrimp processed by the shrimp processing systems described herein. 
     In one or more embodiments, it may be preferred that the blade assembly  248  move from its stored position to its severed position in a direction that results in a slicing action of the mud vein in a shrimp  202 . With reference to  FIGS.  16 - 21   , shrimp  202  restrained in a selected severing location on working surface  214  are generally aligned along processing axis  211  such that movement of the blade assembly  248  along a severing direction aligned with the blade actuator axis  247  provides the desired slicing action of a mud vein in the shrimp  202  when the severing direction/blade actuator axis  247  is oriented generally transverse to the processing axis  211 . 
       FIGS.  23 - 24    depict the relative positions of the severing restraint  250  in position on a pair of differently sized shrimp  202  to illustrate the adaptation provided by the notch  254  in severing restraint  250  based on shrimp of different sizes. As discussed herein and, as depicted in  FIGS.  23 - 24   , the path of the cutting edge  249   c  of the blade  249   b  is fixed relative to the severing restraint  250 . In other words, the cutting edge  249   c  of the blade  249   b  passes the same portion of the notch  254  in severing restraint  250  regardless of the size of the shrimp  202 . 
     In particular,  FIG.  23    depicts a larger shrimp  202  in a selected severing position and aligned with the processing axis  211  on a working surface  214  of a shrimp processing system as described herein.  FIG.  24    depicts a smaller shrimp  202  in a selected severing position and aligned with the processing axis  211  on a working surface  214  of a shrimp processing system as described herein The shrimp  202  are both shown in cross-section with the mud vein  203  located proximate the dorsal side of the shrimp  202 . 
       FIGS.  23 - 24    depict the ability of the notch  254  in severing restraint  250  to assist in determining a height of the ventral side of the shell of the shrimp and setting a cutting depth relative to that height for a blade of a mud vein severing apparatus as described herein. Axis  257  depicted in  FIGS.  23 - 24    may, for example, be indicative of the path of a blade used to sever a mud vein of a shrimp relative to the notch  254 . In particular, axis  257  may be indicative of the path of the lowermost end  249   d  of the cutting edge  249   c  of the blade assembly  248 . The axis  257  is generally parallel with the severing direction/blade actuator axis  247  along which the blade assembly  248  is moved during the severing process. 
     With reference to  FIGS.  23 - 24    , axis  257  may define a cutting depth d along a vertical axis extending through the working surface  214  and the shrimp  202 . Defining the cutting depth relative to the dorsal side of the shrimp shell using a notched severing restraint such as, for example, severing restraint  250  may assist in assuring that cutting depths on shrimp restrained in a selected severing location as described herein are deep enough to sever the mud vein, without undesirably cutting too deeply into a shrimp being processed by the mud vein severing apparatus. 
     As noted above,  FIG.  24    depicts a smaller shrimp  202  in the selected severing position and also aligned with the processing axis  211  on the working surface  214  of a shrimp processing system as described herein.  FIG.  24    also depicts the axis  257  along which the lowermost end  249   d  of the cutting edge  249   c  moves as the blade  249   b  passes through the smaller shrimp  202  to sever the mud vein  203 . 
     A comparison of  FIGS.  23  and  24    shows that the axis  257  along which the lowermost end  249   d  of the cutting edge  249   c  moves to sever the mud veins  203  in both the larger and smaller shrimp  202  is in the same position relative to the severing restraint  250  regardless of the size of the shrimp. In both instances, however, the cutting edge  249   c  of the blade  249   b  of the blade assembly  248  is in position low enough to sever the mud veins  203  of the shrimp  202 . 
     Fixing the height of the path of the blade  249   b  relative to the severing restraint  250  provides for accurate and repeatable severing of mud veins in shrimp of relative widely varying sizes because the mud veins  203  are located closer to the dorsal side of shrimp as a percentage of the “height” of the abdomen of the shrimp  202  in larger shrimp as compared to smaller shrimp (compare, for example, the locations of the mud veins  203  of the larger shrimp in  FIG.  23    and the smaller shrimp in  FIG.  24   ). 
     Another feature that can be visualized with reference to  FIGS.  23  and  24    is that the cutting edge  249   c  of the blade  249   b  will, in most instances, force the mud veins  203  of both the larger and smaller shrimp  202  away from the ventral sides and towards the dorsal sides of the shrimp  202  (i.e., away from the working surface  214  against which the ventral surfaces of the larger and smaller shrimp  202  face). That lifting action can, in some instances, assist with severing of the mud veins  203  which can, in some instances, be relatively tough and/or elastic. Although the lifting action occurs with a curved cutting edge, it will be understood that a similar lifting action could be achieved with a straight cutting edge that also faces away from the ventral side of the shrimp  202 . 
     As discussed herein, the severing restraint  250  used in one or more embodiments of the mud vein severing apparatus described herein preferably includes a notch  254 . The notch  254  is configured to receive a shrimp  202  held in a clamp  212  in the selected severing location on working surface  214  as described herein. In addition to assisting with restraint of a shrimp positioned in the notch  254 , the notch also provides positioning for a blade used to sever the mud vein of a shrimp as described herein. 
       FIGS.  25 A- 25 E  illustrate various features regarding the depicted illustrative embodiment of notch  254 . In particular, the notch  254  may be described as extending inwardly from leading edges  255  of restraint  250  towards a notch end  256  along a notch axis  253 . Notch axis  253  may preferably be transverse to the processing axis  211  when the restraint  250  is in its restraint position proximate a working surface as described herein. Furthermore, the notch  254  may preferably be wider proximate the leading edges  255  of restraint  250  and narrow when approaching the notch end  256  distal from those leading edges. 
     In one or more embodiments, the notch  254  may preferably have a beveled surface  258  that widens when moving in one direction along processing axis  211 . This feature is seen in, for example,  FIGS.  25 B- 25 E . Because of the beveled surface  258 , the notch  254  is wider on one side of severing restraint  250  than on the opposite side of severing restraint  250 . In one or more embodiments, that widening may preferably correlate with the widening of the abdomen of a shrimp when moving from the tail of the shrimp towards its carapace and, as a result, may assist in restraining shrimp when the severing restraint  250  is in its restraint position on a shrimp. 
       FIG.  25 C  is an enlarged cross-sectional view of the severing restraint  250  taken along the notch axis  253 . As can be seen in this figure, the beveled surface  258  forming the notch  254 , in addition to changing the width of the notch  254  as seen in  FIG.  25 B , also changes the height or depth of the notch  254  between the tail side  259   t  and the carapace side  259   c  of the severing restraint  250 . In one or more embodiments, the beveled surface  258  may define an angle α (alpha) relative to the processing axis  211 . In one or more embodiments the angle α (alpha) may be 15 or more, 30 or more, 45 or more, or 60 or more degrees at a lower end and 75° or less, 60° or less, 45° or less, or 30° or less at an upper end. 
       FIGS.  25 D and  25 E  depict the severing restraint  250  on two differently sized shrimp  202  to illustrate the effect that the beveled surface  258  may have when placing the severing restraint  250  on differently sized shrimp. In  FIG.  25 D  a larger shrimp  202  is depicted with a ventral surface facing the working surface  214 . In embodiments in which the severing restraint  250  is rotated into position (see, for example, the mud vein severing apparatus depicted in  FIGS.  16 - 21   ), the angle of the severing restraint  250  (as represented by the notch axis  253 ) may be less vertical when placed on a larger shrimp as seen in  FIG.  25 D  as compared to the more vertical angle of the severing restraint  250  when placed on a smaller shrimp as seen in  FIG.  25 E . 
     That change in angular orientation of the severing restraint  250  on differently sized shrimp may be, at least in part, accommodated by the beveled surface  258  of the notch  254  in one or more embodiments of a severing restraint as described herein. Moreover, the accommodation made by the beveled surface  258  on larger shrimp may, in one or more embodiments, also assist in moving the axis  257 , which defines the cutting depth as discussed above in connection with  FIGS.  23 - 24   , farther down or deeper into the shrimp  202  on the larger shrimp and, conversely, moving the axis  257  upward towards the dorsal side of the shrimp  202  on smaller shrimp. 
     One illustrative embodiment of the components that may be used to provide a measurement module that may be used to measure shrimp in one or more embodiments of a shrimp processing system as described herein are depicted in  FIGS.  26 - 30   . Although described and depicted separately, in one or more embodiments of processing stations described herein, a mud vein severing apparatus and a shrimp measurement module may be integrated into the same processing station. In one or more embodiments, the measurement modules described herein may preferably use a noncontact sensor configured to measure the length of a shrimp held in a clamp moving through the measurement module along a measurement direction. In general, the measurement direction will align with the processing direction as defined by processing axis  211 . 
     Regardless of whether or not the measurement module is integrated into the same processing station as a mud vein severing apparatus, the measurement module may preferably be positioned such that shrimp moving through a shrimp processing system as described herein are measured before, or at least as, they reach the selected severing location at which the mud vein is severed. Doing so can allow the system to use the length of the shrimp to properly position the mud vein severing apparatus with respect to each shrimp for accurate and efficient severing of the mud veins of shrimp processed using the shrimp processing systems described herein. 
     With reference to  FIGS.  26  and  28   , the measurement module components are located on opposite sides of the measurement direction/processing axis  211  such that shrimp moving along the processing axis  211  pass between the components of the measurement module. In particular, the depicted illustrative embodiment of the measurement module includes an emitter  262  and a receiver  264  positioned on opposite sides of the processing axis  211 . The specific embodiment of emitter  262  is in the form of an array of infrared emitters which generate a multipath light beam, while the receiver  264  receives that emitted energy and uses it to determine the length of a shrimp passing between the emitter  262  and the receiver  264 . 
     With reference to  FIGS.  26 - 27  &amp;  30   , the array of emitters forming emitter  262  (arranged vertically in  FIGS.  26 - 27   ) in the depicted embodiment emit light generally across the opening between the emitter  262  and receiver  264 . With reference to  FIGS.  28 - 30   , the receiver  264  may, in one or more embodiments, have an aperture over which light emitted by the emitters  262  is received such that only light within the depicted fan shaped distribution of energy  266  between the emitter  262  and receiver  264  is received by the receiver  264 . 
     In operation, it may be preferred to calibrate the noncontact sensor before a shrimp held in a clamp passes through the noncontact sensor in the measurement direction. In one or more embodiments, it may be preferred to calibrate the noncontact sensor before every shrimp held in a clamp passes through the noncontact sensor in the measurement direction. Calibration of the noncontact sensor before each shrimp held in a clamp passes through the noncontact sensor may provide for more robust and accurate measurement of shrimp passing through the noncontact sensor. In one or more alternative embodiments, it may be preferred to calibrate the noncontact sensor after a selected number of shrimp have passed through the noncontact sensor (as opposed to calibrating the noncontact sensor before every shrimp passes through the noncontact sensor). 
     During the measurement process, the emitter  262  continuously emits optical energy across the gap between the emitter  262  and the receiver  264  while a shrimp restrained in a clamp passes between the emitter  262  and receiver  264  along the processing axis  211 . The controller to which the emitter  262  and receiver  264  are operably attached monitors the energy received by the receiver  264  to identify a junction between the clamp and a shrimp held in the clamp when moving a shrimp held in a clamp through the noncontact sensor. That junction can, in one or more embodiments, be detected by identifying a selected portion of a clamp such as, for example, the leading edge of the clamp restraining a shrimp as the clamp and shrimp pass between the emitter  262  and receiver  264  along the processing axis  211  when the amount of energy emitted by the emitter  262  reaching the receiver  264  falls below a selected clamp threshold value indicating blockage of the energy consistent with the clamp passing between the emitter  262  and receiver  264 . 
     As the shrimp and clamp continue to pass between the emitter  262  and receiver  264 , the controller continues to monitor the energy received by the receiver  264 . While the shrimp is located between the emitter  262  and receiver  264  the amount of energy received by the receiver  264  is reduced due to blockage by the abdomen and carapace of the shrimp. As, however, the carapace of the shrimp passes between the emitter  262  and receiver  264 , the amount of energy received by the receiver  264  increases as the carapace completes its passage between the emitter  262  and receiver  264 . 
     A shrimp length measurement value is determined when the amount of energy reaching the receiver  264  increases to a level above a selected antenna threshold at which point the carapace of the shrimp has passed between the emitter  262  and receiver  264  (referred to as an antenna threshold because, presumably, only antenna of the shrimp may be located between the emitter  262  and receiver  264  after the carapace has passed between those components). 
     Because the controller is also operably connected to the conveying system (see, e.g., controller  290  and conveying system  292  in  FIG.  15   ) used to move the shrimp restrained in clamps through the measurement module between the emitter  262  and receiver  264 , the length of the shrimp can be determined based on the distance traveled by the shrimp using the conveying system. In particular, the distance traveled by a shrimp in the time between identification of the leading edge of the clamp (as determined by the energy received by the receiver  264  falling below a selected clamp threshold) and identification of the end of the carapace of the shrimp (as determined by the energy received by the receiver  264  rising above a selected antenna threshold) is used as a measurement of the length of the shrimp. 
     Although one illustrative embodiment of a measurement module may rely on infrared energy emitted and received by a noncontact sensor, other forms of noncontact sensing may be used in place of and/or in addition to infrared energy emission and detection. For example, noncontact sensing may be performed using ultrasonic energy, optical energy outside of the infrared range, imaging systems (using one or more cameras, etc.), capacitive sensing, imaging systems (using one or more cameras, etc.), etc. In still other alternative embodiments, contact sensing may be used to determine the length of the shrimp using, for example, mechanical followers, fluid jets, etc. 
     With length of the shrimp determined, the controller may, optionally, be configured to determine a weight of the shrimp based at least in part on the length of the shrimp. In some embodiments, the weight of a shrimp held in a clamp may be based entirely on the length of the shrimp as measured using a measurement module as described herein. 
     Further, with the length of the shrimp determined, that information may be used to position the vein severing apparatus relative to that specific shrimp such that the vein severing apparatus can sever the mud vein of the shrimp at a selected location on the shrimp. With reference to  FIG.  3   , it may be preferred to sever the mud vein of a shrimp  102  proximate a junction between a rearmost abdominal shell segment and an adjacent abdominal shell segment of the shrimp, wherein the rearmost abdominal shell segment is located between the adjacent abdominal shell segment and the tail of the shrimp. For example, in a shrimp  102  having an abdomen with six segments, it may be preferred to sever the mud vein proximate a junction between the fifth shell segment and sixth shell segment in the abdomen  104 . Severing the mud vein at that location may result in removal of substantially all of the mud vein, with only the portion of the mud vein located in the rearmost/sixth abdominal segment (width that portion of the mud vein sometimes referred to as the “hind gut”) remaining when the majority of the mud vein is removed from the abdomen  104  between the rearmost/sixth abdominal segment and the carapace of the shrimp  102 . 
     Because the length of the shrimp  202  is known, the general location of the junction between the rearmost and adjacent (for example, fifth and sixth) shell segments is also known because the location of that junction is related to the length of the shrimp  202  and the vein severing module can be positioned properly such that the blade severs the mud vein proximate the junction between the rearmost and adjacent (for example, fifth and sixth) shell segments. 
     As discussed above in connection with  FIGS.  16 - 23   , the illustrative processing station depicted in those figures includes a carriage  244  configured to move along axis  241  which is aligned with processing axis  211  along which shrimp  202  is positioned on working surface  214 . Carriage  244  can be moved using a vein severing module drive (see, e.g., severing module drive  271  in  FIG.  15   ). Although not shown in  FIGS.  16 - 23   , the vein severing module drive (271) operably attached to the carriage  244  to move carriage  244  may take any suitable form including, for example, electric motors, hydraulic motors, pistons (hydraulic and/or pneumatic), solenoids, etc. 
     Moving carriage  244  also moves the blade assembly  248  along the processing axis  211  because blade actuator  245  and blade carriage  246  are both mounted on carriage  244  along with the severing restraint  250  and its associated components. As a result, with knowledge of the location of blade assembly  248  relative to carriage  244  and a measurement of the shrimp  202  located in the selected severing location on the working surface  214  providing the general location of the junction between the fifth and sixth shell segments on the shrimp  202 , the mud vein severing apparatus depicted in  FIGS.  16 - 23    can position the blade assembly  248  such that the blade assembly  248  severs the mud vein proximate the selected junction on the shrimp  202  when moving from its stored position to its severed position as described herein. 
     Heading Apparatus &amp; Methods 
     As discussed herein, one or more embodiments of the shrimp processing systems and methods described herein may include a processing station and methods of heading individual shrimp. As used herein, “heading” of a shrimp means removal of the head/carapace (and substantially all of the viscera located therein) from the abdomen of a shrimp. In one or more embodiments, the shrimp may be restrained on a working surface during heading using a heading restraint, with the heading restraint being, in one or more embodiments, positioned at the junction between the abdomen and the carapace of the shrimp (referred to herein as the “carapace junction”). 
     In one or more embodiments, the head of the shrimp be removed in a manner that also results in removal of a significant portion of the mud vein, but removal of the mud vein during heading is not required. Removal of the mud vein during heading may be facilitated if the mud vein is severed at a selected location along the abdomen before heading the shrimp. In one or more embodiments, the mud vein may, as described herein, be severed proximate a junction between the rearmost and adjacent (for example, fifth and sixth) shell segments on the abdomen before heading the shrimp. 
     The shrimp processing systems and methods described herein involve a heading process performed on each shrimp individually while the shrimp is restrained by a head restraint acting on the shrimp at a location proximate the carapace junction. In one or more embodiments, the shrimp may also be restrained by a clamp acting on its abdomen between the carapace junction and the tail, but that additional restraint is not required for the heading process. For example, in one or more embodiments, the shrimp may be restrained by a clamp acting on the abdomen of the shrimp proximate its tail. 
       FIGS.  31 - 33    are simplified diagrams depicting one illustrative embodiment of a heading process and apparatus as described herein, while  FIG.  34    depicts a heading apparatus in the form of a schematic block diagram. As depicted in  FIG.  31   , a shrimp  302  is positioned on a working surface  314 . The shrimp  302  is positioned such that it extends along a processing axis  311  away from a clamp  312  attached to a clamp mount  310 . More specifically, the shrimp  302  is restrained by clamp  312  proximate its tail, such that the abdomen  304  and carapace  308  of the shrimp extend away from the clamp  312  on the working surface  314 . 
     A heading restraint  350  is positioned opposite the working surface  314 . The heading restraint as depicted in  FIG.  31    is located in its stored position such that the shrimp  302  can be positioned between the heading restraint  350  and the working surface  314 . A spoon  360  is also depicted in  FIG.  31    with the spoon  360  being in its ready position in which the spoon  360   is located proximate a carapace side of the heading restraint  350  (where the carapace side of the heading restraint  350  is the side of the heading restraint facing the carapace  308  of the shrimp  302 ). 
     The heading restraint  350  is depicted in its restraint position in  FIG.  32    which is closer to the working surface  314  than when the heading restraint  350  is in its stored position as seen in  FIG.  31   . When moved to its restraint position, the heading restraint  350  is configured to force the shrimp  302  located between the heading restraint  350  and the working surface  314  against the working surface  314 . The spoon  360  remains in its ready position proximate the carapace side of the heading restraint  350  in  FIG.  32   . In the illustrative embodiment depicted in  FIGS.  31 - 32   , the heading restraint  350  and spoon  360  may sever the shrimp  302  at a location proximate its carapace junction  303  (that is, the junction  303  between the abdomen  304  and the carapace  308  of the shrimp). 
     With reference to  FIG.  33   , the heading restraint  350  remains in its restraint position as seen in  FIG.  32   , while the spoon  360  has been moved to its finish position spaced away from the carapace side of the heading restraint  350 . Moving the spoon  360  from its ready position as seen in  FIG.  32    to its finish position as seen in  FIG.  33    separates the head/carapace  308  of the shrimp  302  on the working surface  314  from the abdomen  304 . 
     Also depicted in  FIG.  33    is that the spoon  360  (more particularly a working portion of the spoon  360 ), moves away from the abdomen  304  and heading restraint  350  along a spoon path  301 . In the depicted embodiment, at least a portion of the spoon path  301  is arcuate. Further, in the depicted embodiment, the working portion of the spoon  360  moves closer to the working surface  314  as the spoon  360  moves away from the abdomen  304  of the shrimp and heading restraint  350 . 
     In one or more embodiments, separation of the carapace  308  from the abdomen  304  of the shrimp  302  may also result in removal of at least a portion of the mud vein  303  from the abdomen  304  of the shrimp  302 . Removal of the mud vein  303  may be facilitated if the mud vein is severed within the abdomen  304  before the carapace  308  of the shrimp is removed from the abdomen  304  of the shrimp  302 . As discussed herein, for example, it may be desirable to sever the mud vein  303  in the abdomen  304  proximate the junction between the rearmost and adjacent (for example, fifth and sixth) shell segments on abdomen  304 . 
     Described in a different manner, the heading process as depicted in  FIGS.  31 - 33    may be described as a method in which the abdomen  304  of the shrimp  302  is restrained in a fixed position on a working surface  314  and moving a spoon  360  through the shrimp proximate a carapace junction  303  of the shrimp  302  (the carapace junction  303  being located between the carapace  308  and a first abdominal segment in the abdomen  304  of the shrimp  302 ). Moving the spoon  360  through the shrimp proximate the carapace junction  303  may involve moving the spoon  360  towards the working surface  314 . The method further includes moving the spoon  360  away from the abdomen  304  while restraining the abdomen  304  of the shrimp  302  in the fixed position on the working surface  314 . 
     With reference to  FIG.  34   , one illustrative embodiment of a heading apparatus as described herein is depicted in a schematic block diagram in which a heading restraint  350  and heading restraint actuator  352  are carried on a heading apparatus shuttle  344  along with a spoon  360  and spoon actuator  362 . 
     The shuttle actuator  345  is operably connected to the controller  390 , with the shuttle actuator  345  being used to move the shuttle such that the spoon  360  and heading restraint  350  are positioned at a selected location on a shrimp during the heading process. The heading restraint actuator  352  is operably connected to the controller  390 , with the heading restraint actuator being used to move the heading restraint between its stored position and its restraint position as described herein. The spoon actuator is operably connected to the controller  390 , with the spoon actuator  362  being used to move the spoon  360  from its ready position to its finish position to remove the carapace of a shrimp restrained by the heading restraint  350 . 
     Controller  390  is also, in one or more embodiments, operably connected to an optional carapace sensor to assist with identification of the carapace junction as described herein. In one or more embodiments of shrimp processing systems as described herein in which a measurement module is used to measure the shrimp being processed, that measurement may be used to identify the area in which the carapace junction is likely located to speed identification of the carapace junction as described herein. In one or more alternative embodiments, the location of the carapace may be determined based on the measured length of the shrimp using, e.g., the measurement apparatus and methods described herein. In the depicted illustrative embodiment, the carapace sensor includes an emitter  368  and a receiver  369 , with the emitter  368  emitting energy received by the receiver  369 . Variations in the amount of energy received by the receiver can be used to identify the carapace junction as described herein. 
     Conveying system  392  is also operably attached to the controller  390 , with the conveying system being used to move individual shrimp into position on a working surface where the shrimp may be acted on by the heading restraint  350  and spoon  360  as described herein. 
     Although the controller  390  depicted in connection with the illustrative embodiment of a heading apparatus as depicted in  FIG.  34    is in the form of a single controller in which all control functions may be performed by a single controller (although backup and/or redundant controllers may be provided to assist in the case of failure of a primary controller), one or more alternative embodiments of shrimp heading apparatus may include a distributed set of controllers, with those portions of the apparatus requiring a controller having a dedicated controller and, potentially, a network may be used to interconnect the various controllers to facilitate processing of shrimp by the heading apparatus. Further, the controller  390  (or any other controllers used in a heading apparatus as described herein) may be separate from or integrated into a system controller such as, e.g., controller  90  depicted in connection with a control system used to control a shrimp processing system as depicted in  FIG.  2   . 
     The controllers used in one or more embodiments of heading apparatus as described herein may be provided in any suitable form and may, for example, include memory and a controller. The controller may, for example, be in the form of one or more microprocessors, Field-Programmable Gate Arrays (FPGA), Digital Signal Processors (DSP), microcontrollers, Application Specific Integrated Circuit (ASIC) state machines, etc. The controllers may include one or more of any suitable input devices configured to allow a user to operate the apparatus (e.g., keyboards, touchscreens, mice, trackballs, etc.), as well as display devices configured to convey information to a user (e.g., monitors (which may or may not be touchscreens), indicator lights, etc.). 
     One illustrative embodiment of a heading apparatus that may be used in one or more embodiments of shrimp processing systems and methods described herein is depicted in  FIG.  35   . The depicted heading apparatus  340  is positioned above the selected heading location above the working surface  314  located along a processing axis  311 . As described herein, individual shrimp are moved into a selected heading location along the processing axis  311  in the direction of the arrow located below working surface  314  and axis  311  so that they are located on the working surface  314  in a position, for example, a selected heading location, to be acted on by the heading apparatus  340 . 
     The heading apparatus includes a heading apparatus  344  supported on a frame  342  above the working surface  314 . The shuttle  344  in the depicted illustrative embodiment is configured to move along a shuttle axis  341  aligned with the processing axis  311 . In one or more embodiments, the shuttle  344  may move along one or more slides  343  aligned with shuttle axis  341 . Shuttle  344  may be moved using a shuttle actuator  345  operably connected to the shuttle  344  using any suitable drive system. 
     The illustrative embodiment of heading apparatus  340  also includes a heading restraint  350  position above the working surface  314  and a heading restraint actuator  352  operably connected to move the heading restraint  350  between a stored position (as seen in  FIG.  35   ) and a restraint position (as seen in, for example,  FIGS.  46 - 47    (described more completely below)). In the depicted illustrative embodiment, movement of the heading restraint  350  from its stored position to its restraint position involves rotating the heading restraint  350  about axis  351 . Although not visible in  FIG.  35   , the heading apparatus includes a spoon operably connected to a spoon actuator  362  used to move the spoon from its ready position to its finish position as described herein. 
     Also depicted in  FIG.  35    is one portion of an optional carapace sensor that may be used to determine where shuttle  344  is positioned to properly place heading restraint  350  on a shrimp located on the working surface  314 . In particular, a receiver  369  of a noncontact carapace sensor system is depicted along one side of shuttle  344  in  FIG.  35   . 
       FIGS.  36 - 37    are enlarged views of portions of the heading apparatus  340  depicted in  FIG.  35   . In particular,  FIG.  36    depicts the heading restraint  350  along with a portion of heading restraint actuator  352 , both of which are carried by shuttle  344  supported by frame  342  for movement along slide  343  defining shuttle axis  341 . Spoon actuator  362  is also depicted in  FIG.  36    along with working surface  314  which extends along processing axis  311  as described herein.  341 . 
       FIG.  37    is a slightly more enlarged view depicting receiver  369  of a noncontact carapace sensor system along with a projection of a beam path (depicted in a broken line) emanating from an emitter  368  and directed towards the receiver  369 . The emitter  368  and receiver  369  of the carapace sensor system are, in the depicted embodiment, carried on the shuttle  344  as seen in, for example,  FIGS.  36 - 37   . The beam path may, in one or more embodiments, preferably be transverse to the processing axis  311  as depicted in  FIG.  37   . Movement of the shuttle  344  along the processing axis  311  after a shrimp is located in a selected heading location on the working surface  314 , therefore, moves the carapace sensor system relative to the shrimp to accurately detect the carapace junction as described herein. 
       FIG.  38    is a view of the heading apparatus  340  taken from the opposite side as depicted in  FIG.  35    with one side of the shuttle  344  removed to expose components located within shuttle  344 .  FIG.  38    also includes a shrimp  302  located on working surface  314  in what can be referred to as a selected heading location on working surface  314 . Shrimp  302  is restrained by a clamp  312  carried on a clamp mount  310  in a manner similar to other clamps and clamp mounts as described herein. 
     Also exposed by removal of one side of shuttle  344  are a drive gear  346  operably connected to the depicted illustrative embodiment of shuttle actuator  345  along with a belt  347  used to move shuttle  344  along the processing axis  311  as needed to properly position the heading restraint  350  above shrimp  302  located in the selected heading position on working surface  314 . Although a belt  347  and drive gear  346  are used in the depicted embodiment of shuttle actuator  345 , many other mechanisms could be used to move the shuttle  344  as described herein (for example, a lead screw and follower, a rack and pinion, etc.). Heading restraint  350  is, as described herein, rotated about heading restraint axis  351  using heading restraint actuator  352  to move heading restraint  350  between its stored and restraint positions as described herein (with the heading restraint  350  being located in its stored position in  FIG.  38   ). 
     Other features exposed by removal of a portion of shuttle  344  are a spoon  360  along with spoon actuator  362 . Spoon actuator  362  is operably connected to spoon  360  to rotate spoon  360  about spoon axis  361  in the depicted illustrative embodiment of heading apparatus  340 . 
       FIGS.  39 - 41    depict various views of one illustrative embodiment of a heading restraint  350  that may be used in one or more embodiments of a heading apparatus as described herein. The heading restraint  350  includes a contact portion  355  configured to contact and at least partially sever a shrimp located on a working surface proximate the carapace junction of the shrimp when the heading restraint is in its restraint position as described herein. Contact portion  355  extends downwardly from mounting portion  357  used to mount the heading restraint  350  in the heading apparatus  340 . 
     The depicted illustrative embodiment of heading restraint  350  also includes a guide  358  extending away from the contact portion  355  of the heading restraint  350  along the direction of processing axis  311 . In the depicted illustrative embodiment, the guide  358  is in the form of a pair of wings  359  extending away from the contact portion  355  of heading restraint  350 . 
     Another optional feature depicted in connection with the illustrative embodiment of heading restraint  350  is a beveled edge  356  located on contact portion  355 , with the beveled edge  356  facing the working surface  314  when the heading restraint  350  is in its restraint position. The beveled edge  356  may facilitate passage of the contact portion  355  of the heading restraint  350  through a shrimp as the heading restraint  350  is moved from its stored position to its restraint position as described herein. 
     Heading restraint  350  also includes an optional restraint notch  354  located in contact portion  355  with the restraint notch  354  terminating at end  353 . Restraint notch  354  opens towards a working surface and a shrimp located thereon when heading restraint  350  is in its restraint position relative to a working surface  314  as described herein. In one or more embodiments, restraint notch  354  may provide clearance for a mud vein of a shrimp during the heading process such that the mud vein is not severed by the contact portion of the heading restraint  350  when the heading restraint  350  is moved into its restraint position. 
     In one or more embodiments, the restraint notch  354  may have a depth dr measured between the beveled edge  356  and the notch end  353  in a direction transverse to the processing axis  311 . The depth dr may, in one or more embodiments, be long enough such that the heading restraint  350  can be used with shrimp of a variety of sizes while still providing the functions of restraint during heading as well as reducing the likelihood of severing the mud vein during heading. 
       FIG.  42    depicts one illustrative embodiment of a spoon  360  that may be used in one or more embodiments of a heading apparatus as described herein.  FIG.  43    depicts an enlarged view of a portion of the spoon  360  when in the ready position proximate the contact portion  355  of a heading restraint as described herein, with the working portion  365  of the spoon located within the guide defined by the wings  359  of heading restraint  350 . 
     The working portion  365  of spoon  360  is configured to contact and at least partially sever a shrimp located on a working surface proximate the carapace junction of the shrimp when the spoon  360  is in its ready position and the heading restraint  350  is in its restraint position as described herein. The working portion  365  of spoon  360  extends downwardly from mounting portion  367  used to mount the spoon  360  in the heading apparatus  340 . In one or more embodiments, the mounting portion  367  of the spoon  360  may include features (such as, e.g., pins or posts as seen in  FIG.  42   ) configured to define and a spoon axis  361  about which spoon  360  rotates when moving from its ready position to its finish position. 
     The illustrative embodiment of spoon  360  depicted in  FIG.  42    includes an optional beveled outer edge  366  located on the working portion  365  of the spoon  360 . A portion of the beveled outer edge  366  faces the working surface  314  when the spoon  360  is in its ready position and the heading restraint  350  is in its restraint position. The beveled outer edge  366  may facilitate passage of the working portion  365  of the spoon  360  through a shrimp as the heading restraint  350  is moved from its stored position to its restraint position while the spoon  360  is in its ready position as described herein. 
     Spoon  360  also includes an optional spoon notch  364  located in working portion  365 , with the spoon notch  364  terminating at end  363 . Spoon notch  364  opens towards a working surface and a shrimp located thereon when spoon  360  is in its ready position and heading restraint  350  is in its restraint position relative to a working surface  314  as described herein. In one or more embodiments, spoon notch  364  may provide clearance for a mud vein of a shrimp during the heading process such that the mud vein is not severed by the working portion  365  of the spoon  360  when the spoon is in the ready position and the heading restraint  350  is moved into its restraint position. 
     In one or more embodiments, the spoon notch  364  may have a depth ds measured from the opening of the notch  364  to the end  363  of spoon notch  364  (that is, in a direction along a length of the spoon notch  364 ). In one or more embodiments, the opening of the spoon notch  364  may be defined by a line extending between the junctions of the beveled outer edge  366  with the opening of the spoon notch  364 . The depth ds of spoon notch  364  may, in one or more embodiments, the long enough such that the spoon  360  can be used with shrimp of a variety of sizes while still providing the functions of separating the carapace during heading, as well as reducing the likelihood of severing the mud vein during heading. 
     In one or more embodiments, the spoon notch  364  may have a depth ds measured from a distal end of the working portion  365  of the spoon  360  (where the distal end of the working portion of the spoon  360  may be defined by a line connecting the junctions of the beveled outer edge  366  at the opening of notch  364 ) to the end  363  of notch  364  that is 10 millimeters or more, and, optionally, wherein the depth of the spoon notch is 20 millimeters or less. The width of the notch proximate a midpoint of the depth of the notch  364  may be, for example, 2 millimeters or more on the lower end and 4 millimeters or less on the upper end. When the spoon  360  is in its ready position and the heading restraint  350  is in its restraint position, the depth ds of the spoon notch  364  can be measured along a length of the notch in a direction transverse to the processing axis  311  extending along working surface  314  as seen in, for example,  FIG.  32   . 
     With reference to  FIGS.  39 - 41  and  43   , one or more embodiments of the spoon and heading restraint having a guide used in one or more embodiments of a heading apparatus as described herein may include a spoon having a spoon width that is less than a guide width of the guide. This relationship can be seen in, for example,  FIG.  43   , where working portion  365  of spoon  360  fits within the guide as defined by wings  359  extending away from contact portion  355  of heading restraint  350 . 
     In one or more embodiments, the spoon width and the guide width may be measured at the widest point of the working portion of the spoon located in the guide (which may also be described as being in a direction transverse to a path of the working portion of the spoon when the working portion of the spoon is moving away from the contact portion of the heading restraint as the spoon moves from the ready position to the finish position as described herein. In one or more embodiments, the maximum width of the working portion of the spoon located in the guide may be described as having a width that is 50% or more, 60% or more, 70% or more, 80% or more, or 90% of the guide width at that location. In one embodiment, the width of the working portion of the spoon may be approximately 16 millimeters in a guide width of approximately 22 millimeters. 
     In one or more embodiments of the heading apparatus as described herein including a heading restraint having a contact portion with a beveled edge and a working portion of a spoon having a beveled outer edge, the beveled outer edge  366  of the working portion  365  of the spoon  360  and the beveled edge  356  of the contact portion  355  of the heading restraint  350  are adjacent each other when the spoon  360  is in the ready position such that the working portion  365  of spoon  360  is proximate the contact portion  355  of the heading restraint  350 . In such an arrangement, that bevels on the beveled outer edge  366  of the spoon  360  and the beveled edge  356  of the heading restraint  350  face away from each other such that the working portion  365  of the spoon  360  and the contact portion  355  of the heading restraint  350  form a double bevel edge when the spoon  360  is in the ready position. 
     One or more embodiments of a heading apparatus as described herein may include a carapace sensor configured to detect a carapace junction between a carapace and an abdominal segment of a shrimp.  FIGS.  44 - 45    can be used to describe detection of the carapace junction and proper positioning of the heading restraint and spoon based on detection of the carapace junction. 
     Many of the components of the heading apparatus  340  as depicted in  FIG.  38    are also depicted in  FIGS.  44 - 45   , including heading restraint  350  and heading restraint actuator  352 , both of which are located on heading shuttle  344  for rotation about axis  351 . Shuttle  344  is attached to frame  342  for movement along one or more slides  343  aligned with shuttle axis  341 . Also depicted in  FIGS.  44 - 45    are a shrimp  302  located on working surface  314 , the shrimp  302  restrained by a clamp  312  used to transport or convey the shrimp along the processing axis  311 . Other features depicted in  FIGS.  44 - 45    includes the spoon actuator  362  used to move the spoon  360  from its ready position adjacent the heading restraint  352  its finish position as described herein. 
     In one or more embodiments, the carapace sensor may detect the carapace junction located between the carapace and the first abdominal segment of a shrimp. In one or more embodiments, the controller operably connected to the carapace sensor (see, e.g., controller  390  in  FIG.  34   ) may be configured to detect a change in opacity between a carapace and an abdominal segment of a shrimp on a working surface and identify the carapace junction based, at least in part, on that change in opacity. In general, the carapace is darker or more optically dense than the abdomen of a shrimp (due, for example, to the viscera located within the carapace and the thicker shell of the carapace) which facilitates optical detection of the carapace junction as described herein. In one or more alternative embodiments, the location of the carapace junction may be determined based on the measured length of the shrimp (measured using, e.g., one or more of the measurement apparatus and methods described herein) such that optical detection of the carapace junction is not required. 
     As described above in connection with  FIGS.  36 - 37   , one illustrative embodiment of a carapace sensor may include an emitter and receiver, with the emitter emitting optical energy which passes through a shrimp before reaching the receiver when a shrimp is located between the emitter and the receiver. Changes in the amount of optical energy reaching the receiver as the carapace sensor moves along a length of the shrimp can be used to identify the carapace junction. 
     As implemented in connection with the illustrative heading apparatus  340  and with reference to  FIGS.  44 - 45    in addition to  FIGS.  36 - 37   , the emitter  368  and receiver  369  may be located on the shuttle  344  such that the emitter  368  and receiver  369  are located on opposite sides of a shrimp  302  located on a working surface  314  above which the heading apparatus  340  is positioned. The emitter  368  and receiver define an optical path that, in one or more embodiments, may be located above the working surface  314 . 
     With reference to  FIGS.  44 - 45   , the shuttle  344  can be moved along a shuttle axis  341  that is aligned with the processing axis  311 . That movement can be effected using a shuttle actuator as described in connection with, for example,  FIGS.  34  and  35   . The heading restraint  350  and spoon  360  are, as described herein, mounted on the heading apparatus shuttle  344 . In one or more embodiments, a system controller (for example, controller  390  in  FIG.  34   ) may be configured to operate the shuttle actuator  345  to position the heading apparatus shuttle  344   such that the heading restraint  350  is positioned on a first abdominal segment of a shrimp  302  on the working surface  314 . 
     In particular, the heading restraint may be positioned adjacent the carapace junction of the shrimp  302  when the heading restraint  350  is in the restraint position on a shrimp  302  on the working surface  314 . In one or more embodiments, the heading restraint  350  may preferably be located on the abdominal side of the carapace junction. When so positioned, the spoon  360  may preferably contact a shrimp  302  on the working surface  340  proximate the carapace junction of the shrimp  302  on the carapace side of the heading restraint  350  when the heading restraint is in the restraint position on the shrimp  302  on the working surface  314 . In one or more embodiments, the spoon  360  may preferably contact a shrimp  302  on the working surface  314  at the carapace junction of the shrimp  302 . 
     As seen in  FIG.  44   , the heading apparatus shuttle  344  may be positioned such that the carapace sensor (as represented by emitter  368  in this view) is positioned to detect the shrimp  302  on working surface  314  within its abdomen. In particular, the carapace sensor may be positioned proximate the clamp  312 . While operating the carapace sensor, the shuttle  344  may be moved towards the carapace of the shrimp  302  (that is, away from the clamp  312 ), with the controller identifying the carapace junction when the signal received from the receiver  369  of the carapace sensor  368 / 369  indicates that the amount of energy received by the receiver has fallen below a selected carapace junction threshold. 
     Because the opacity of individual shrimp can vary to a point at which detection of the carapace junction may be difficult if the selected carapace junction threshold is fixed, one or more embodiments of heading apparatus as described herein may include a controller that is configured to calibrate the carapace sensor on one or more abdominal segments of each shrimp  302  on the working surface  314  before operating the shuttle actuator  345  to position the heading apparatus shuttle such that the heading restraint is properly positioned on a shrimp on the abdominal side of the carapace junction. 
       FIG.  45    depicts the heading apparatus  340  after the shuttle  344  is moved along the abdomen of the shrimp  302  located on working surface  314  (along with the directions of both shuttle axis  341  and processing axis  311 ). In the depicted illustration, the carapace sensor (represented by emitter  368  in  FIG.  45   ) is positioned at the carapace junction. With the location of the carapace junction known, the shuttle actuator  345  can be operated to move the shuttle such that the heading restraint  350 , when moved from its stored position to its restraint position, is located on the abdominal side of the carapace junction such that the spoon (not seen in  FIG.  45   ) is located proximate, preferably at, the carapace junction when the heading restraint  350  is in its restraint position. 
       FIGS.  46 - 47    depicts operation of the illustrative embodiment of heading apparatus  340  to remove the head of shrimp  302 . To facilitate a view of the operation of the heading apparatus, the side panels of the shuttle  344  have been removed so that components located between the side panels of the shuttle  344  are exposed. Among the components depicted in  FIGS.  46 - 47    are heading restraint  350  and heading restraint actuator  352 , along with spoon  360  (including the working portion  365  of spoon  360  in  FIG.  47   ) and spoon actuator  362 . These components are shown while the heading restraint  350  is in its restraint position on the abdomen of a shrimp  302  restrained on working surface  314  using clamp  312 . Also depicted in  FIGS.  46 - 47    are spoon axis  361  extending through the mounting portion  367  of the spoon  360 . 
     In particular, in  FIG.  46    the heading restraint  350  is shown in position on the abdomen of the shrimp  302  while the spoon  360  is in its ready position relative to the heading restraint  350  such that the working portion of the spoon is in position proximate the carapace junction, preferably at the carapace junction, of the shrimp  302 . The working portion  365  of spoon  360  is not visible in  FIG.  46    because it is located on the opposite side of the wings  359  used to guide the carapace of the shrimp during removal. As discussed herein, it may be preferred that the heading restraint  350  be located on the first abdominal segment of the shrimp  302  such that the heading restraint  350  could be described as being on the abdominal side of the carapace junction which, as discussed herein, is the junction between the first abdominal segment of the shrimp  302  and its carapace. 
       FIG.  47    depicts the heading apparatus  340  after the spoon  360  has been moved from its ready position to its finish position. In particular, spoon  360  has been rotated about spoon axis  361  such that the working portion  365  of spoon  360  is now spaced away from the heading restraint  350  which continues to restrain the abdomen of the shrimp  302  on working surface  314 . Although the spoon  360  in the depicted illustrative embodiment of a heading apparatus as described herein rotates when moving between its ready position and its finish position, one or more embodiments of heading apparatus as described herein may include a working portion of a spoon that moves in a linear or translational motion when moving from its ready position to its finish position. 
     After completing the motion from the ready position to the finish position, one or more embodiments of the heading apparatus described herein may include movement of the spoon  360  back to its ready position along with movement of the heading restraint  350  back to its stored position so that another shrimp  302  can be moved along the processing axis  311  into the selected heading location on working surface  314 . 
     In one or more embodiments, the heading restraint actuator  352  may be in the form of a single acting limited force piston capable of moving the heading restraint  350  between its stored position and its restraint position as described herein. The heading restraint actuator  352  may include a force limiting feature (for example, a spring return cylinder) such that the force of the heading restraint on a shrimp  302  located in the selected heading location on working surface  314  does not exceed a selected force value. Although a spring-loaded pneumatic piston is used to provide the reciprocating motion needed to move the heading restraint  350  between its stored and restraint positions, many other mechanisms could be used to provide the reciprocating motion, for example, double acting pistons, single acting pistons, spring mechanisms, hydraulic actuators, motors, magnetic drivers, etc. 
     Removal of the head or carapace of a shrimp using a heading apparatus as described herein may be facilitated by a spoon actuator  362  that is in the form of a damped pneumatic actuator that provides the spoon  360  with adequate force to remove the carapace of a shrimp  302  in a controlled motion. In one illustrative embodiment, a limited size orifice may be used to control the flow of a hydraulic fluid within the actuator to provide the damping action that may be beneficial to control removal of the heads of shrimp in the heading apparatus described herein. 
     One illustrative embodiment of a damped spoon actuator  362  that may be used in one or more embodiments of a heading apparatus as described herein, is depicted in the cross-sectional views in  FIGS.  48 - 49   . As depicted in those figures, the actuator  362  is in the form of a hydraulically damped pneumatic actuator that includes a main piston  372  and a floating piston  378  located within actuator housing  370 . The main piston  372  is located within an inner housing  384  that is, itself, located within the actuator housing  370 . A main piston port  373  is in fluid communication with a main piston volume  374  located in the actuator housing  370 . A floating piston port  375  is in fluid communication with a floating piston volume  376  also located in the actuator housing  370 . 
     The actuator  362  also includes a working piston volume  380  located in the actuator housing  370  between the main piston  372  and the floating piston  378 . A flow control orifice  382  and damping liquid are both located in the working piston volume  380 . In one or more embodiments, the damping liquid may be in the form of, e.g., mineral oil, although many other hydraulic liquids could be used in place of mineral oil. The flow control orifice  382  separates the working piston volume  380  into a main portion and a floating portion, with the main portion of the working piston volume  380  being located between the main piston  372  and the orifice  382  and the floating portion of the working piston volume  380  being located between the floating piston  378  and the orifice  382 . 
     More particularly, the flow control orifice  382  provides a fluid passage between the main portion and the floating portion of the working piston volume  380 . In the depicted embodiment, the flow control orifice  382  is located in end plug  386  that closes both the actuator housing  370  and the inner housing  384  at the right end of the view of damped spoon actuator  362  depicted in  FIG.  49   .  FIG.  49 A  is a perspective view of the actuator housing  370 , inner housing  384  and end plug  386  (with the actuator housing  370  and inner housing  384  being depicted in phantom lines to allow visualization of the end plug  386 ), with the flow control orifice  382  being provided in the form of a machined slot formed in end plug  386  that allows fluid to pass between the main and floating portions of the working piston volume  380  during use of the actuator  362 . 
     The introduction of fluid such as, for example, air into the main piston volume  374  through the main piston port  373  when at least a portion of the damping liquid is located in the main portion of the working piston volume  380  (that is, the portion of the working piston volume  380  located between the main piston  372  and the orifice  382 ) forces the damping liquid out of the main portion of the working piston volume  380  into the floating portion through the orifice  382  to move the main piston  372  in a first direction relative to the actuator housing  370 . Movement of the main piston  372  in the first direction relative to the actuator housing  370  can be seen in the movement of the main piston  372  from its position in  FIG.  48    to its position in  FIG.  49   . 
     The introduction of fluid such as, for example, air into the floating piston volume  376  through the floating piston port  375  when at least a portion of the damping liquid is located in the floating portion of the working piston volume  380  (that is, the portion of the working piston volume  380  located between the floating piston  378  and the orifice  382 ) forces the damping liquid out of the floating portion of the working piston volume  380  into the main portion through the orifice  382  to move the main piston  372  and a second direction relative to the actuator housing  370 . Movement of the main piston  372  in the second direction relative to the actuator housing  370  can be seen in the movement of the main piston  372  from its position in  FIG.  49    to its position in  FIG.  48   . 
     The flow control orifice  382  may take a variety of forms such as, for example, an opening formed by drilling, milling, etc. (see, for example,  FIG.  49 A ), a needle valve, or any other suitable flow restriction construction capable of limiting the flow rate of a liquid moving between the main and floating portions of the working piston volume  380 . 
     In one or more embodiments of a damped actuator as described herein, the main piston volume  374  may have a maximum main piston volume that is greater than a volume of the damping liquid in the working piston volume  380 . In one or more embodiments of a damped actuator as described herein, the floating piston volume  376  may have a maximum floating piston volume that is greater than the volume of the damping liquid in the working piston volume  380 . In one or more embodiments of a damped actuator as described herein, both of the main piston volume  374  and the floating piston volume  376  may have maximum piston volumes that are greater than the volume of the damping liquid in the working piston volume  380 . 
       FIG.  50    depicts a variety of shrimp processed by one illustrative embodiment of a heading apparatus as described herein. In particular, the shrimp depicted in  FIG.  50    illustrate one potential advantage of a heading apparatus and methods of heading as described herein. The shrimp  302   a ,  302   c , and  302   d  differ from the shrimp  302   b  in that the shrimp  302   b  retains a significant portion of the neck meat  303 . Proper shaping and positioning of the heading restraint and spoon in a heading apparatus as described herein, along with use of a force limited actuator to move the heading restraint from its stored position to its restraint position and a velocity limited damped actuator to move the spoon from its ready position to its finish position may, result in retention of a significant amount of the neck meat  303  on shrimp processed using the heading apparatus and methods described herein. It should, however, be understood that in one or more embodiments, a clean cut during removal of the carapace may be preferred over retention of the neck meat. In one or more embodiments, increasing the force of the heading restraint may assist in severing the shrimp at the carapace junction in a cleaner, more defined manner. 
     Peeling Apparatus &amp; Methods 
     As discussed herein, one or more embodiments of the shrimp processing systems and methods described herein may include a peeling apparatus and methods of removing the shells of shrimp. The peeling apparatus may, in one or more embodiments, the capable of removing the shell segments on the dorsal side of the abdomen of shrimp (the abdominal somites) as well as removing the pleopods (swimmerets) along with the pereiopods (walking legs) found on the ventral side of the abdomen of shrimp. In one or more alternative embodiments, the peeling apparatus and methods described herein may only remove the pleopods (swimmerets) along with the pereiopods (walking legs) found on the ventral side of the abdomen of shrimp, leaving the shell segments on the dorsal side of the abdomen of shrimp intact. 
     The shrimp processing systems and methods described herein involve a peeling process performed on each shrimp individually while the shrimp is located in a selected location in a peeling apparatus as described herein. In one or more embodiments, the shrimp may be restrained by a clamp acting on its abdomen at the junction between the rearmost (for example, sixth) abdominal shell segment and the tail/uropod of each shrimp during the peeling process. 
       FIGS.  51 - 52    are simplified diagrams depicting one illustrative embodiment of a peeling apparatus  440  as described herein, while  FIG.  53    depicts a peeling apparatus control system in the form of a schematic block diagram. The peeling apparatus  440  depicted in  FIG.   51    includes a lower roller assembly  450  and an upper roller assembly  460 . The lower roller assembly  450  and upper roller assembly  460  are positioned on opposite sides of a processing axis  411  passing through the peeling apparatus  440  as depicted in  FIGS.  51 - 52   . As discussed herein, the processing axis  411  defines the path of a shrimp through the various stations in processing systems as described herein including, for example, the peeling apparatus  440  depicted in  FIGS.  51 - 52   . 
     As in other apparatus used in shrimp processing systems as described herein, the shrimp moving along processing axis  411  may be supported by a working surface  414 . In the depicted embodiment of peeling apparatus  440 , the working surface  414  is separated into two sections located on each side of the lower roller assembly  450  an upper roller assembly  460 , with a shrimp being supported between the lower roller assembly  450  an upper roller assembly  460  during the actual peeling process. As a result, working surfaces  414  serve to support a shrimp moving into the space between lower roller assembly  450  an upper roller assembly  460  and after the shrimp leaves the space between the roller assemblies  450  and  460 . 
     The lower roller assembly  450  includes a pair of lower rollers mounted side-by-side for rotation about axes  451  and the upper roller assembly  460  includes a pair of upper rollers mounted side-by-side for rotation about axes  461 . In the view depicted in  FIG.  51   , only one of the lower rollers of lower roller assembly  450  and only one of the upper rollers of upper roller assembly  460  are visible because the second rollers in each assembly are positioned behind the upper and lower rollers viewed in  FIG.  51   . 
       FIG.  52    is an upper view taken along a roller shuttle axis  441  that extends through the lower roller assembly  450  and upper roller assembly  460  in a direction generally transverse to the processing axis  411 . As a result, the pair of upper rollers of upper roller assembly  460  are visible in  FIG.  52    while the pair of lower rollers  450  are not visible in  FIG.  52    because they are positioned beneath the upper roller assembly  460 . 
     One or more embodiments of peeling apparatus as described herein include a roller shuttle that is configured to move one or both of the lower roller assembly  450  and the upper roller assembly  460  between a receiving position and an operating position. The lower roller assembly  450  and upper roller assembly  460  are located farther from each other when the lower roller assembly  450  and the upper roller assembly  460  are in the receiving position than when the lower roller assembly  450  an upper roller assembly  460  are in the operating position. With reference to  FIG.  51   , the peeling apparatus  440  is designed such that the upper roller assembly  460  moves while the lower roller assembly  450  remains stationary when the lower roller assembly  450  an upper roller assembly  460  are moved from their receiving position to their operating position. It should, however, be understood that peeling apparatus as described herein may be designed such that the lower roller assembly  450  moves while the upper roller assembly  460  remains stationary or, alternatively, both the lower roller assembly  450  and the upper roller assembly  460  move when moving the roller assemblies  450  and  460  between their receiving and operating positions. 
     Movement of the upper roller assembly  460  is illustrated in  FIG.  51   , where upper roller assembly  460  as depicted in solid lines is in the receiving position while upper roller assembly  460 ′ (in broken lines) depicts the position of the upper roller assembly  460  when the upper and lower roller assemblies  450  and  460  are in their operating positions to remove the shell of a shrimp located between the upper and lower roller assemblies  450  and  460 . 
     Another feature depicted in  FIGS.  51  to  52    that may be found in one or more embodiments of peeling apparatus as described herein is an alignment device  470  positioned on the working surface  414  such that shrimp being moved between the lower roller assembly  450  an upper roller assembly  460  along the processing axis  411  pass over the alignment device  470 . As discussed herein, shrimp are moved through the processing stations along a processing axis  411  with the shrimp oriented tail first. In other words, the tail of the shrimp passes between upper and lower roller assemblies  450  and  460  followed by the abdomen of the shrimp. 
     In one or more embodiments, the shrimp may be oriented such that the dorsal side of the shrimp faces the upper roller assembly  460  while the ventral side of the shrimp faces lower roller assembly  450 . As a result, pleopods and pereiopods located on the ventral side of a shrimp preferably contact the alignment device  470  such that the pleopods and pereiopods may be aligned along the ventral side of the shrimp to facilitate their removal by the lower roller assembly  450 . More specifically, the pleopods and pereiopods (if present) may preferably be aligned such that they extend along the abdomen of the shrimp and away from its tail. 
     The alignment device  470  may take a variety of forms including, for example, a bed of bristles facing upward away from the working surface  414  along a direction aligned with shuttle axis  441 . Although a bed of bristles may be used for alignment device  470 , many other textured surfaces could be used to provide the alignment functions described herein. For example, posts, roughened surfaces (for example, sandpaper-like or other structured surfaces, etc.), channels, etc. may be used in place of a bed of bristles for alignment of the pleopods and pereiopods on a shrimp passing over the alignment device  470 . One example of a potentially suitable alignment device may be a section of a brush having polyester bristles with a diameter of approximately 0.2 millimeters (see, for example, “Food-Grade Tight-Seal Strip Brush” No. T7442T11 from McMaster Carr Company (mcmaster.com)). 
       FIG.  53    is a schematic block diagram depicting one control system that may be used in connection with the peeling apparatus  440  depicted in  FIGS.  51 - 52   . The control system includes a controller  490  and a conveying system  492  operably connected to the controller. As mentioned herein, the conveying system  492  can be used to move shrimp into and out of the peeling apparatus  440 . The controller  490  is also operably connected to both a lower roller assembly drive  452  and an upper roller assembly drive  462 , as well as a roller shuttle actuator  446 . 
     In one or more embodiments, the lower roller assembly drive  452  is operably connected to the pair of lower rollers and configured to rotate a first lower roller about a first lower roller axis  451  passing through the first lower roller and rotate a second lower roller about a second lower roller axis  451  passing through the second lower roller. The upper roller assembly drive  462  is operably connected to the pair of upper rollers and configured to rotate a first upper roller about a first upper roller axis  461  passing through the first upper roller and rotate a second upper roller about a second upper roller axis  461  passing through the second upper roller. 
     The controller  490  is also operably connected to the roller shuttle actuator used to move one or both of the lower roller assembly  450  and the upper roller assembly  460  between their receiving and operating positions as described herein. 
     Although the controller  490  is depicted in the form of a single controller in which all control functions may be performed by a single controller (although backup and/or redundant controllers may be provided to assist in the case of failure of a primary controller), one or more alternative embodiments of peeling apparatus may include a distributed set of controllers, with those portions of the apparatus requiring a controller having a dedicated controller and, potentially, a network may be used to interconnect the various controllers to facilitate processing of shrimp by the peeling apparatus. Further, the controller  490  (or any other controllers used in a peeling apparatus as described herein) may be separate from or integrated into a system controller such as, e.g., controller  90  depicted in connection with a control system used to control a shrimp processing system as depicted in  FIG.  2   . 
     The controllers used in one or more embodiments of peeling apparatus as described herein may be provided in any suitable form and may, for example, include memory and a controller. The controller may, for example, be in the form of one or more microprocessors, Field-Programmable Gate Arrays (FPGA), Digital Signal Processors (DSP), microcontrollers, Application Specific Integrated Circuit (ASIC) state machines, etc. The controllers may include one or more of any suitable input devices configured to allow a user to operate the apparatus (e.g., keyboards, touchscreens, mice, trackballs, etc.), as well as display devices configured to convey information to a user (e.g., monitors (which may or may not be touchscreens), indicator lights, etc.). 
     One illustrative embodiment of a peeling apparatus as described herein is depicted in  FIGS.  54 A- 54 D . In particular,  FIG.  54 A  is a perspective view of the depicted illustrative embodiment of a peeling apparatus,  FIG.  54 B  is a side view of the illustrative embodiment of a peeling apparatus of  FIG.  54 A , with the upper and lower roller assemblies in the operating position as described herein; and  FIG.  54 C  is a side view of the illustrative embodiment of a peeling apparatus of  FIG.  54 A , with the upper and lower roller assemblies in the receiving position as described herein. At least a portion of a schematic depiction of a shrimp  402  is provided in each of  FIGS.  54 A- 54 D , these figures do not include a clamp used to retain the tail of the shrimp  402  on the working surface  414  on the downstream side of the peeling apparatus  440 . It should be understood, however, that the tail of the shrimp  402  is retained on that downstream working surface  414  during the peeling process by a clamp similar to, e.g., clamps  212  and  312  depicted in connection with the vein severing and heading apparatus described herein. 
     The peeling apparatus includes a lower roller assembly  450  including a pair of lower rollers and an upper roller assembly  460  including a pair of upper rollers. Each of the lower rollers  450  rotates about its own axis  451 , while each of the upper rollers  460  rotate about their own axes  461 . Those axes  451  and  461  may, in one or more embodiments, preferably be generally aligned with a processing axis  411  along which shrimp pass when moving into and out of the peeling apparatus  440 . 
     In the depicted illustrative embodiment, upper roller assembly  460  is attached to a shuttle  444  used to move the upper roller assembly  460  towards and away from the lower roller assembly  450  (to move the roller assemblies between their operating position (see  FIGS.  54 A &amp;  54 B ) and their receiving position (see  FIG.  54 C )). The shuttle  444  is supported on a frame  442  which also supports roller shuttle actuator  446  operably connected to roller shuttle  444  using a drive pulley  447  and belt  448  in the depicted embodiment. In the depicted embodiment, roller shuttle actuator  446  may be in the form of an electric motor rotating drive pulley  447 . It should, however, be understood that many other drive mechanisms can be used to move roller shuttle  444  towards and away from the lower roller assembly  450 . For example, hydraulic and/or pneumatic pistons, magnetic drives, etc. could all be used in place of the electric motor and drive belt system depicted in connection with the illustrative embodiment of peeling apparatus  440  depicted in  FIGS.  54 A- 54 C . Further, in one or more embodiments, the weight of the roller shuttle alone  444  may be selected and/or adjusted to apply the desired force on the dorsal surface of a shrimp  402  located in the peeling apparatus  440  such that no driving force is required other than gravity. 
     Lower roller assembly  450  and upper roller assembly  460  are positioned between a pair of working surfaces  414 , one of which is located upstream of the roller assemblies  450  and  460  and the other of which is located downstream of those roller assemblies. As a result, shrimp moving into and out of the peeling position between the lower roller assembly  450  and the upper roller assembly  460  move off of the upstream working surface  414  and onto the downstream working surface  414  as they pass through the peeling apparatus  440  along processing axis  411 . 
     Other components depicted in  FIGS.  54 A- 54 C  include a lower roller assembly drive  452  operably connected to the lower rollers of lower roller assembly  450  and an upper roller assembly drive  462  operably connected to the upper rollers of the upper roller assembly  460 . In the depicted illustrative embodiment, the upper roller assembly drive  462  may preferably be mounted on the roller shuttle  444  such that the upper roller assembly drive  462  moves with the upper roller assembly  460  to simplify driving of the upper rollers about their axes as described herein. 
     Although the axes  451  and  461  about which the rollers of the lower and upper roller assemblies  450  and  460  rotate may be generally aligned with the processing axis  411 , in one or more embodiments, one or more of the lower roller axes  451  may not be parallel with one or more of the upper roller axes  461 . For example, in one or more embodiments one or more of the lower roller axes  451  may converge with the upper roller axis  461  directly above the corresponding lower roller when moving along the processing axis  411  in the processing direction as described herein. The convergence between the lower roller axes  451  and upper roller axes  461  is schematically depicted in  FIG.  54 B , where angle β (beta) is the angle formed between the lower roller axes  451  and the upper roller axes  461 . In one or more embodiments, the convergence angle β (beta) may be greater than 0°, 1° or more, 2° or more, 3° or more, 4° or more, or 5° or more. At an upper end, the convergence angle β (beta) may be 5° or less, 4° or less, 3° or less, 2° or less, 1° or less, or greater than 0°. Convergence of the lower roller axes  451  and the upper roller axes  461  may, in one or more embodiments, beneficially result in removal of the shell segments closer to the tail of a shrimp before removal of the shell segments located closer to the carapace of the shrimp. This is beneficial because the shell segments overlap slightly at their junctions, with the trailing edge of the shell segment closer to the carapace being located over the leading edge of the next successive shell segment. 
     Another optional feature that may be found in one or more embodiments of peeling apparatus as described herein are cleaning nozzles  476  directed at the upper rollers of upper roller assembly  460 . The cleaning nozzles  476  may be configured to direct water or other cleaning fluids on the rollers of both the lower roller assembly and the upper roller assembly to remove pleopods, pereiopods, shell segments and other debris between peeling processes. 
       FIG.  54 D  depicts the upper and lower roller assemblies  450  and  460  in an enlarged view. One feature depicted in the enlarged view of  FIG.  54 D  are ribs  454  extending outwardly away from the lower roller and extending along the length of the lower roller. Also seen in the enlarged view of  FIG.  54 D  are shell engagement pins  464  extending outwardly from the upper rollers  460 . 
     Another feature depicted in  FIG.  54 D  is the support plate  467  connecting the ends of upper rollers  460  located opposite the roller shuttle  444  from which upper rollers  460  extend. The support plate  467  assists in maintaining the proper relationship between the pair of upper rollers  460  as they rotate to remove shell segments from shrimp as described herein. 
     Another illustrative embodiment of a peeling apparatus as described herein is depicted in  FIGS.  55 A- 55 D . In particular,  FIG.  55 A  is a perspective view of another illustrative embodiment of a peeling apparatus  440 ′ as described herein with the upper and lower roller assemblies in the receiving position as described herein;  FIG.  55 B  is a perspective view of the peeling apparatus  440 ′ of  FIG.  55 A , with the upper and lower roller assemblies in the operating position as described herein;  FIG.  55 C  is an enlarged side view of the peeling apparatus of  FIG.  55 B  depicting the relationship between a clamp, working surface and lower rollers of this illustrative embodiment; and  FIG.  55 D  is a further enlarged view of a portion of the peeling apparatus depicted in  FIG.  55 C . 
     The peeling apparatus  440 ′ includes a lower roller assembly  450 ′ including a pair of lower rollers and an upper roller assembly  460 ′ including a pair of upper rollers. Each of the lower rollers  450 ′ rotates about its own axis  451 ′, while each of the upper rollers  460 ′ rotate about their own axes  461 ′. Those axes  451 ′ and  461 ′ may, in one or more embodiments, preferably be generally aligned with a processing axis  411 ′ along which shrimp pass when moving into and out of the peeling apparatus  440 ′. The lower rollers  450 ′ extend between tail ends  456 ′ and head ends  458 ′, with the tail ends  456 ′ being located downstream of the head ends  458 ′ (although not numbered, the upper rollers of the peeling apparatus described herein also extend between tail ends and head ends that are also arranged with the tail ends located downstream of the head ends of the upper rollers). 
     In the depicted illustrative embodiment, upper roller assembly  460 ′ is attached to a shuttle  444 ′ used to move the upper roller assembly  460 ′ towards and away from the lower roller assembly  450 ′ in a manner similar to that described herein in connection with peeling apparatus  440  in  FIGS.  54 A- 54 D . 
     Lower roller assembly  450 ′ and upper roller assembly  460 ′ are positioned between a pair of working surfaces  414 ′, one of which is located upstream of the roller assemblies  450 ′ and  460 ′ and the other of which is located downstream of those roller assemblies. As a result, shrimp moving into and out of the peeling position between the lower roller assembly  450 ′ and the upper roller assembly  460 ′ move off of the upstream working surface  414 ′ and onto the downstream working surface  414 ′ as they pass through the peeling apparatus  440 ′ along processing axis  411 ′. 
     Other components depicted in  FIGS.  55 A- 55 B  include a lower roller assembly drive  452 ′ operably connected to the lower rollers of lower roller assembly  450 ′ and an upper roller assembly drive  462 ′ operably connected to the upper rollers of the upper roller assembly  460 ′. In the depicted illustrative embodiment, the upper roller assembly drive  462 ′ may preferably be mounted on the roller shuttle  444 ′ such that the upper roller assembly drive  462 ′ moves with the upper roller assembly  460 ′ to simplify driving of the upper rollers about their axes as described herein. 
     Although the axes  451 ′ and  461 ′ about which the rollers of the lower and upper roller assemblies  450 ′ and  460 ′ rotate may be generally aligned with the processing axis  411 ′, in one or more embodiments, one or more of the lower roller axes  451 ′ may not be parallel with one or more of the upper roller axes  461 ′ and/or the processing axis  411 ′. For example, in one or more embodiments one or more of the lower roller axes  451 ′ may converge with the upper roller axis  461 ′ directly above the corresponding lower roller when moving along the processing axis  411 ′ in the processing direction as described herein. In the illustrative embodiment of peeling apparatus  440 ′, one or both of the lower roller axes  451 ′ may also converge with the processing axis  411 ′ when moving along the processing axis  411 ′. 
     The convergence between the lower roller axes  451 ′, upper roller axes  461 ′, and processing axis  411 ′ is schematically depicted in  FIG.  55 C , where angle θ (theta) is the angle formed between the lower roller axis  451 ′ and the processing axis  411 ′. In one or more embodiments, the convergence angle θ (theta) may be greater than 0° 
     , 1° or more, 2° or more, 3° or more, 4° or more, or 5° or more. At an upper end, the convergence angle θ (theta) may be 5° or less, 4° or less, 3° or less, 2° or less, 1° or less, or greater than 0°. 
     Also depicted in  FIG.  55 C , angle ε (epsilon) is the angle formed between the upper roller axis  461 ′ and the processing axis  411 ′. In one or more embodiments, the convergence angle ε (epsilon) may be greater than 0°, 1° or more, 2° or more, 3° or more, 4° or more, or 5° or more. At an upper end, the convergence angle ε (epsilon) may be 5° or less, 4° or less, 3° or less, 2° or less, 1° or less, or greater than 0°. 
     Convergence between any pair of the lower roller axes  451 ′, upper roller axes  461 ′, and processing axis  411 ′ may, in one or more embodiments, beneficially result in removal of the shell segments closer to the tail of a shrimp before removal of the shell segments located closer to the carapace of the shrimp. This is beneficial because the shell segments overlap slightly at their junctions, with the trailing edge of the shell segment closer to the carapace being located over the leading edge of the next successive shell segment. 
     Another optional feature that may be found in one or more embodiments of peeling apparatus as described herein is an offset between the tail ends  456 ′ of the lower rollers  450 ′ and the working surface  414 ′ adjacent the tail ends  456 ′ of the lower rollers  450 ′. That offset, indicated as do in  FIG.  55 D , results in the tail ends  456 ′ of the lower rollers  450 ′ being located closer to the tail ends of the corresponding upper rollers  460 ′ than the adjacent portion of the working surface  414 ′ as seen in  FIG.  55 D  as measured in a direction transverse to the lower roller axis  451 ′. The offset do results in slight raising of the ventral surface of a shrimp having its tail retained in the clamp  412 ′ located above the working surface  414 ′ as compared to an alternate arrangement in which the tail ends of the lower rollers are flush with or even lower than the working surface  414 ′. The offset do may improve the removal of pleopods and swimmerets on the ventral surface of a shrimp being peeled in the peeling apparatus as well as the shell segments located closer to the tail of the shrimp. 
     Another optional feature depicted in connection with the alternative embodiment of the peeling apparatus  440 ′ depicted in  FIGS.  55 A- 55 D  is the addition of a compression arm  480 ′ to the peeling apparatus  440 ′. In the depicted illustrative embodiment, the compression arm  480 ′ terminates in a working end  482 ′ that is configured to act on the dorsal surface of the tail of shrimp retained in the clamp  412 ′. In one or more embodiments, the working end  482 ′ provides a compressive force to the tail of the shrimp to assist in retaining the shrimp in the clamp  412 ′ during the peeling process. That compressive force is applied through the members  484 ′ and  486 ′ that, together, support the working end  482 ′. The working surface  482 ′ of the compression arm  480 ′ is, in the depicted embodiment, attached to the roller shuttle  444 ′ through members  484 ′ and  486 ′. In the depicted embodiment, the compressive force provided at the working surface  482 ′ is controlled by a resilient connection between the member  486 ′ and the supports  488 ′ attached to the roller shuttle  44 ′, with the resilient connection allowing the member  486 ′ to rotate about compression axis  481 ′. The resilient connection may include one or more of elastomeric materials, torsion springs, etc. 
     In one or more embodiments, the compression arm  480 ′ may be described as being configured to move between a raised position as seen in  FIG.  55 A  and a compression position as seen in  FIG.  55 B  (and partially in  FIG.  55 D ). The working end  482 ′ of the compression arm  480 ′ is located closer to the working surface  414 ′ of the peeling apparatus  440 ′ when the compression arm  480 ′ is in the compression position of  FIGS.  55 B and  55 D ) than when the compression arm  480 ′ is in the raised position of  FIG.  55 A . 
     In embodiments in which the compression arm  480 ′ is operably connected to the roller shuttle  444 ′, the compression arm  480 ′ is in the raised position when the lower roller assembly  450 ′ and the upper roller assembly  460 ′ are in the receiving position (as seen in, e.g.,  FIG.  55 A ), and the compression arm  480 ′ is in the compression position when the lower roller assembly  450 ′ and the upper roller assembly  460 ′ are in the operating position (as seen in, e.g.,  FIG.  55 B ). 
     In one or more embodiments of any peeling apparatus as described herein, the lower rollers may be used to remove pleopods and any pereiopods present on the ventral surface of a shrimp located between the upper and lower roller assemblies  450  and  460 . To facilitate capture of those features, the lower rollers may include raised features to assist with capture of the pleopods and any pereiopods on the ventral surface of a shrimp located above the lower rollers. In one embodiment, the raised features may be in the form of ribs extending along the length of the lower rollers  450 , with the ribs defining, for each roller an inner diameter and an outer diameter wherein the inner diameter is located at the base of each rib and the outer diameter is located at the outermost location of each rib. 
       FIG.  56    schematically depicts one illustrative embodiment of a pair of lower rollers  450  that are configured to capture and remove pleopods and any pereiopods present on the ventral surface of a shrimp located between the upper and lower roller assemblies  450  and  460 . The concepts illustrated in connection with rollers  450  may be used in connection with any peeling apparatus or method described herein. Each of the rollers includes an inner diameter  454  that would represent the base of the raised features on each lower roller. Each of the rollers also includes an outer diameter  455  that would represent the outermost portions of the raised features on each lower roller. As seen in  FIG.  56   , it may be preferred that the outer diameter of one roller is located between the inner and outer diameters of the opposing roller such that the raised features interfere as the rollers rotate about their axes  451 . 
     Interference between the raised features on the pair of lower rollers  450  may involve a complementary meshing of those raised features (for example, ribs from one roller fit within the spaces between the ribs on the opposing roller) and/or the interference may involve deformation of one or both sets of raised features on the lower rollers  450 . In place of elongated ribs, one or more alternative types of raised features may include for example, elastomeric netting wrapped on rollers  450 , structured surfaces on the rollers  450  in the form of pins or posts, knurling, etc. Furthermore, the raised features on the rollers  450  may be the same or different. For example, in one or more embodiments, one roller may be provided with elongated ribs that extend along the length of the roller while the opposing roller may be provided with no raised features or with a different set of raised features. The raised features may be, in one or more embodiments, constructed of elastomeric or resilient materials that deform during the capture and/or removal of pleopods and any pereiopods on a shrimp positioned between the rollers  450 . 
       FIGS.  57 - 58    depict one illustrative embodiment of a pair of upper rollers  460  that may be used in one or more embodiments of a peeling apparatus as described herein. The upper rollers  460  may define a head end  468  and a tail end  469 , with the head end  468  being located upstream of the tail end  469  along the processing axis  411 . In other words, the head ends  468  of the upper rollers  460  are located farther from the tail of a shrimp being processed than the tail ends  469 . The rollers  460  each rotate about an axis  461  and are positioned on opposite sides of the processing axis  411  along which shrimp move into and out of position between the upper rollers  460  for peeling. 
     One or both of the upper rollers  460  may, in one or more embodiments, include shell engagement pins  464  protruding outwardly from the outer surfaces of the upper roller  460  (see, also, pins  464  on rollers  460  in  FIG.  54 D ). The shell engagement pins  464  may be configured to pierce or otherwise capture the shell segments on the abdomen of a shrimp when forced against the shrimp. For example, in one or more embodiments, the shell engagement pins  464  may have tapered bodies having a cross-sectional area that decreases when moving away from the axis of the roller on which the shell engagement pins  464  are located. In one or more embodiments, shell engagement pins  464  may be located in a recess  465  or  466  formed into the outer surface of one or both of the upper rollers  460 . 
     In one or more embodiments, a surface area density of the shell engagement pins  464  may increase when moving along the upper roller axis  461  from the head end  468  towards the tail end  469  of the rollers  460 . The surface area density of the shell engagement pins  464  may increase using a variety of approaches. For example, in one or more embodiments, the spacing between pins  464  may decrease when moving from the head end  468  towards the tail end  469  of the rollers  460 . Decreasing spacing can be seen in, for example, pins  464  located in recesses  465  on rollers  460 . 
     Another manner in which spacing between pins  464  may decrease when moving from the head end  468  towards the tail end  469  of the rollers  460  is by including more than one row of pins  464 . For example, in the illustrative embodiments of upper rollers  460  depicted in  FIG.  57   , a second row of pins  464  is provided on each of the rollers  460 . In one or more embodiments, a first row of pins  464  may extend over or 80% or less, 70% or less, 60% or less, or 50% or less of a length of the upper roller as measured from its head end  468  to its tail end  469 . A second row of shell engagement pins may extend over a distance of 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or substantially all of a length of the upper roller  460  as measured from its head end  468  to its tail end  469 . 
     Another optional feature depicted in connection with the upper rollers of  FIG.  57    is that one or both of the rollers  460  may be tapered such that the roller  460  forms a frusto-conical body that tapers when moving from the tail end  469  towards the head end  468  of the roller  460 . In one or more embodiments, the frusto-conical bodies may define an apex angle of 10° or less, 8° or less, 6° or less, 4° or less, or 2° or less as measured relative to the axis  461  about which the rollers  460  rotate during use. The use of tapered rollers may enhance contact between the shell engagement pins  464  and the shell of a shrimp by adapting more closely to the shape of the abdomen of a shrimp positioned between the upper rollers  460 . 
     The use of tapered upper rollers  460  may also assist in removing the shell segments closer to the tail of a shrimp before removing the shell segments located closer to the carapace of the shrimp . As discussed above in connection with the converging upper and lower roller axes, removal of the rearmost shell segments first is beneficial because the shell segments overlap slightly at their junctions, with the trailing edge of the shell segment closer to the carapace being located over the leading edge of the next successive shell segment. In one or more embodiments, tapered rollers may be used in addition to or in place of converging upper and lower roller axes. 
     Operation of the lower roller assembly  450  an upper roller assembly  460  to remove shell segments from the dorsal side of a shrimp and pleopods and pereiopods from the ventral side of the abdomen of a shrimp can be described with reference to  FIGS.  51 ,  54 ,  56  and  58   . 
     With reference to  FIG.  56   , the controller (see, for example, controller  490  in  FIG.  53   ) operably connected to the lower roller assembly drive  452  used to rotate lower rollers  450  as described herein may be configured to operate the lower roller assembly drive  452  to rotate each of the lower rollers about a capture arc, with the opposing rollers  450  rotating in opposite directions over their respective capture arcs. As depicted in  FIG.  56   , each of the rollers  450  may be rotated over a capture arc  457 . 
     In one or more embodiments, the capture arc may be defined by time and/or by distance. For example, the capture arcs  457  may be the result of rotating the rollers  450  for a selected period of time using the lower roller assembly drive. Alternatively, the capture arcs  457  may be the result of rotating the rollers  450  over a selected rotational distance. For example, the capture arcs  457  may involve rotation over an arc of 20° or more, 30° or more, 45° or more, 60° or more, 75° or more, 90° or more, etc. 
     In still other embodiments, the capture arcs  457  may be variable. For example, in one or more embodiments, the lower roller assembly drive may rotate one or both of the rollers  450  until a selected amount of resistance to rotation is encountered with that resistance defining capture of the pleopods and pereiopods present on the ventral side of a shrimp. 
     Rotating the first and second rollers  450  about their respective capture arcs  457  may, in one or more embodiments, collect and hold at least one pleopod, a majority of the pleopods on the ventral side of the shrimp, and preferably all of the pleopods and any pereiopods that remain after heading on the ventral side of the abdomen of a shrimp located between the upper and lower roller assemblies  450  and  460 . In addition, capture of the pleopods and pereiopods may also assist in positioning and/or straightening the abdomen of the shrimp before attempting to remove shell segments from the dorsal side of the shrimp abdomen. 
     After rotating the lower rollers of the lower roller assembly  450  about their respective capture arcs, the roller shuttle actuator  446  may be operated to move the upper roller assembly  460  towards the lower roller assembly  450  such that the upper and lower roller assemblies  450  and  460  are moved from the receiving position to the operating position in which the upper rollers of upper roller assembly  460  contact the shell segments on the dorsal side of the shrimp abdomen. 
     In one or more embodiments, the roller shuttle actuator  446  may be configured to provide a limited force to the abdomen of a shrimp located between the lower and upper roller assemblies  450  and  460 . For example, in one or more embodiments in which the roller shuttle actuator  446  is in the form of an electric motor, a torque sensor may be used to determine the force applied to a shrimp located between the lower and upper roller assemblies  450  and  460  as the upper roller assembly is moved against the abdomen of the shrimp. Many other techniques and methods of controlling the force applied to the abdomen of a shrimp located between the lower and upper roller assemblies  450  and  460  force may, alternatively, be used (for example, pressure-controlled pneumatic cylinder or force-limited pneumatic cylinder, etc.). 
     After the roller shuttle actuator  446  moves the roller shuttle  444  carrying upper roller assembly  460  into place such that the upper rollers of upper roller assembly  460  contact the dorsal side of the shrimp abdomen with a sufficient force, the upper roller assembly drive  46   2  may be operated by the controller to rotate each of the upper rollers  460  about a peeling arc sufficient to remove shell segments from the abdomen of a shrimp. 
       FIG.  58    depicts one example of a pair of peeling arcs  480 . In one or more embodiments, the peeling arcs  480  of the upper rollers  460  may be in opposite directions. In other words, the upper rollers  460  may be rotated in opposite directions such that the shell segments on the dorsal side of a shrimp located between upper rollers  460  are drawn into the gap between the rollers  460  as the shell segments are removed from the abdomen of the shrimp. In one or more embodiments, the peeling arcs  480  may involve rotation of the rollers  460  over an arc of 90° or more, 120° or more, 150° or more,   or more, 240° or more, 300° or more, or 360° or more. 
     At essentially the same time as upper rollers  460  are rotating about their peeling arcs  480 , the lower roller assembly drive  452  may rotate the lower rollers  450  about their axes over a removal arc to remove the pleopods and pereiopods from the ventral side of the abdomen of the shrimp at the same time as the upper rollers  460  are removing the shell segments from the dorsal side of the abdomen of the shrimp. As a result, the shell segments on the dorsal side of a shrimp abdomen and the pleopods and pereiopods on the ventral side of the shrimp abdomen may be removed at the same time. 
     In one or more embodiments, the removal arcs over which the lower rollers  450  are rotated (see, for example, removal arcs  458  in  FIG.  56   ) may be greater than the capture arcs  457  over which the lower rollers  450  are rotated to capture the pleopods and pereiopods before attempting to remove the shell segments from the dorsal side of the abdomen of the shrimp. In one or more embodiments, the removal arcs may involve rotation of the lower rollers of the lower roller assembly over an arc of 60° or more, 70° or more, 80° or more, 90° or more, 120° or more, 150° or more, 180° or more, 240° or more, 300° or more, or 360° or more. 
     After operating the lower roller assembly to remove the pleopods and pereiopods on the ventral side of the shrimp and the shell segments from the dorsal side of the shrimp, the conveying system may be used to remove the shrimp from its position between the lower and upper roller assemblies  450  and  464  further processing. In general, however, it should be noted that the peeling station may preferably be located at the end of a shrimp processing system line such that the shrimp is, after being processed by a peeling apparatus as described herein ready to be unloaded from a clamp or other restraint and if desired, sorted based on size or other physical characteristics known about the shrimp from its processing in any of the other stations in a shrimp processing system described herein. 
     As discussed above, one or more embodiments of peeling apparatus and methods described herein may only remove the pleopods (swimmerets) along with the pereiopods (walking legs) found on the ventral side of the abdomen of shrimp, leaving the shell segments on the dorsal side of the abdomen of shrimp intact. Such shrimp may, for example, be marketed as “shell-on” shrimp and/or “peel and eat” shrimp, with the peeling process being simplified because the pleopods (swimmerets) along with the pereiopods (walking legs) found on the ventral side of the abdomen of shrimp will have already been removed from the abdomen of the shrimp. 
     The peeling apparatus described above can be used to perform this selective removal process by simply holding the upper rollers of the upper roller assembly  460  stationary about perspective axes while the lower rollers are operated as discussed above to remove the pleopods (swimmerets) along with the pereiopods (walking legs) found on the ventral side of the abdomen of shrimp. It may, however, be beneficial to move the upper roller assembly  460  and lower roller assembly  450  between the receiving and operating positions as discussed above, with the upper roller assembly  460  serving to stabilize the shrimp during removal of the pleopods (swimmerets) along with the pereiopods (walking legs). 
     Although removal of the pleopods (swimmerets) along with the pereiopods (walking legs) while leaving the shell segments on the dorsal side of the abdomen of shrimp intact may be accomplished using the peeling apparatus and methods described and discussed above in connection with  FIGS.  51 - 58   , one or more alternative embodiments of peeling apparatus and methods may involve replacing the upper roller assembly with a stabilizing unit which can be referred to herein as an upper assembly. 
     One illustrative embodiment of an arrangement in which an upper assembly is used to replace an upper roller assembly is depicted schematically in  FIG.  59   . More specifically, a lower roller assembly  450 ′ is depicted including lower rollers that rotate about lower roller axes  451 ′ in a manner similar to that described above with respect to lower roller assembly  450 . Also depicted in  FIG.  59    are an abdomen of the shrimp  402 ′ depicted in a cross-sectional view. The abdomen of the shrimp  402 ′ extends along a processing axis  411 ′ which is generally aligned with the lower roller axes  451 ′. 
       FIG.  59    also includes an upper assembly  460 ′ it can be used to stabilize the dorsal surface of the shrimp  402 ′ during removal of the pleopods (swimmerets) along with the pereiopods (walking legs) in a manner similar to that described above with respect to the peeling apparatus depicted and described in connection with  FIGS.  51 - 58   . 
     The upper assembly  460 ′ and the lower roller assembly  450 ′ are movable towards and away from each other between a receiving position and an operating position in a manner similar to that described above with respect to the peeling apparatus depicted and described in connection with  FIGS.  51 - 58   . Although either or both of the upper assembly  460 ′ and lower roller assembly  450 ′ may be moved to place those components in the receiving position or operating position as desired, upper assembly  460 ′ is shown spaced apart from the lower roller assembly  450 ′ in a receiving position as upper assembly  460 ″ (in broken lines). It should be understood that, alternatively, the lower roller assembly  450 ′ could be moved towards a stationary upper assembly  460 ′ as discussed herein in connection with the peeling assembly depicted and described in connection with  FIGS.  51 - 58   . 
     Shell Segment Separator Apparatus &amp; Methods 
     As discussed herein, one or more embodiments of the shrimp processing systems and methods described herein may include a shell segment separator apparatus and methods of separating shell segments of shrimp. As discussed herein, it should be understood that the shell segment separator separates the shell segments located on the dorsal surface of the abdomen of shrimp processed using systems and described herein. Separation of adjacent pairs of shell segments may, in one or more embodiments, assist in clean removal (during peeling) of abdominal shell segments located forward (that is, closer to the carapace) of the rearmost abdominal shell segment (where the rearmost abdominal shell segment is the shell segment located forward of the tail of the shrimp). 
     In some species of shrimp, physiological structures or connections between the rearmost abdominal shell segment and the adjacent abdominal shell segment may result in tearing of either or both of the rearmost abdominal shell segment and an adjacent abdominal shell segment. In shrimp including, for example, six abdominal shell segments (see, for example,  FIG.  3   ), removal of the abdominal shell segments without separating the fifth and sixth abdominal shell segments as described herein may result in tearing of either or both of the fifth or sixth abdominal shell segments. 
     As with other shrimp processing systems and methods described herein, the shell segment separator apparatus is performed on each shrimp individually while the shrimp is located in a selected location relative to the shell segment separator apparatus as described herein. In one or more embodiments, the shrimp may be restrained by a clamp acting on its abdomen at the junction between the rearmost (for example, sixth) abdominal shell segment and the tail/uropod of each shrimp. 
       FIG.  60    is a perspective view of one illustrative embodiment of a shell segment separator apparatus  540  as described herein, while  FIG.  61    depicts a shell segment separator apparatus control system in the form of block diagram. The shell separator apparatus  540  depicted in  FIG.  60    includes a first shell segment retainer  550  and a second shell segment retainer  560  positioned along a processing axis  511  passing through the shell segment separator apparatus  540 . As discussed herein, the processing axis  511  defines the path of shrimp through the various stations in processing systems as described herein including, for example, the shell segment separator apparatus  540  depicted in  FIG.  60   . Also seen in  FIG.  60    is a shrimp  502  restrained by a clamp  512 , with the shrimp  502  in a selected location on a working surface relative to the shell segment separator apparatus  540 . 
     The shell segment separator apparatus  540  also includes a carriage  544  located above the working surface  514  with the carriage  544  being movable along a carriage axis  541  to position the working portions of the shell segment separator  540  relative to the shrimp when the shrimp is in a selected location on working surface  514 . In addition, the shell segment separator apparatus  540  also includes a separation shuttle  570  configured to move along a shuttle axis  571  to move the second shell segment retainer  560  relative to the first shell segment retainer  550  to separate adjacent shell segments on shrimp  502  as described herein. The actuators used to physically move the carriage  544  and the separation shuttle  570  along their respective axes are located within housing  542  of shell segment separator apparatus  540  as depicted in  FIG.  60   . Although the depicted actuators provide translational motion to separate adjacent shell segments, rotary motion could be used, especially if the rotary motion is relative to an axis of rotation displaced far enough away from the processing axis  511  that results, functionally, in motion that approximates linear movement along the processing axis  511  at the location where the shell segments are separated as described herein. 
       FIG.  61    is a schematic block diagram depicting one control system that may be used in connection with the shell segment separator apparatus  540  depicted in  FIG.  60   . The control system includes a controller  590  and a conveying system  592  operably connected to the controller  590 . As mentioned herein, the conveying system  592  can be used to move shrimp into and out of the selected location relative to the shell segment separator apparatus  540 . The controller  590  is also operably connected to the first retainer actuator  555  the second retainer actuator  565  and a separation actuator  575 . 
     The first retainer actuator  555  is provided to move the first shell segment retainer  550  between its ready configuration and its retention configuration. The second retainer actuator  565  is provided to move the second shell segment retainer  560  between its ready configuration and its retention configuration. The separation actuator  575  is provided to move the second shell segment retainer  560  between its initial position and a separation position after operating the first retainer actuator  555  to move the first shell segment retainer  550  from its ready configuration to its retention configuration and after operating the second retainer actuator  565  to move the second shell segment retainer  560  from its ready configuration to its retention configuration. In the depicted illustrative embodiment, the separation actuator  575  moves the separation shuttle  570  on which the second shell segment retainer is located to move the second shell segment retainer  560  between its initial position and its separation position. 
       FIGS.  62  and  63    are enlarged perspective views of the shell segment separator apparatus of  FIG.  60    with the first and second shell segment retainers  550  and  560  in their respective ready configurations. As depicted in the figures, a shrimp  502  is restrained in a clamp  512  in a selected location on working surface  514 , with the shrimp up  02  aligned along the processing axis  511 . 
     In the depicted illustrative embodiment, the first shell segment retainer  550  includes a pair of jaws  552  that are configured to rotate about axes  551 . Each of the jaws  552  includes one or more pins  554  that are configured to pierce an abdominal shell segment of the shrimp  502  when moved to their retention configuration as described herein. Although both jaws  552  includes pins  554 , it should be understood that in one or more alternative embodiments, pins may not be located on both jaws  552  of a first shell segment retainer  550  of a shell segment separator apparatus as described herein. 
     With reference to  FIG.  63   , a first retainer actuator  555  is depicted and is configured to move a shuttle  556  relative to the carriage  544  to rotate jaws  552  about their respective axes  551 . Although the depicted first retainer actuator  555  is in the form of a pneumatic cylinder, any of the actuators described herein may take any suitable form including, for example, electric motors, hydraulic motors, pistons (hydraulic and/or pneumatic), solenoids, etc. 
     Similarly, the second shell segment retainer  560  includes a pair of jaws  562  that are configured to rotate about axes  551 . Each of the jaws  562  also includes one or more pins  564  that are configured to pierce an abdominal shell segment of a shrimp  502  when moved to their retention configuration as described herein. Again, although both jaws  562  include pins  564 , it should be understood that in one or more alternative embodiments, pins may not be located on both jaws  562  of a second shell segment retainer  560  of a shell segment separator apparatus as described herein. 
     While first shell segment retainer  550  is fixed in position relative to the carriage  544 , the second shell segment retainer  560  is mounted on separation shuttle  570  for movement relative to the first shell segment retainer  560  and carriage  544 . As described herein, the first shell segment retainer  550  and second shell segment retainer  560  are mounted on carriage  544  for movement along the processing axis  511 . Movement of the carriage  544  moves the first and second shell segment retainers  550  and  560  relative to the clamp  512  restraining shrimp  502  on working surface  514  so that the first shell segment retainer  550  and second shell segment retainer  560  can be properly positioned with the junction of a pair of adjacent shell segments located between the first shell segment retainer  550  and second shell segment retainer  560 . 
     Proper positioning of the shell segment separator apparatus  540  relative to the clamp  512  and/or shrimp  502  on working surface  514  may be achieved using, in one or more embodiments, data from a measurement apparatus as described herein, with the general location of the selected junction between adjacent shell segments being determined based on the size of each shrimp. 
       FIG.  64    is an enlarged perspective view of the shell segment separator apparatus of  FIG.  63    with the first and second shell segment retainers  550  and  560  in their respective retention configurations. With respect to the illustrative embodiments of the first and second shell segment retainers  550  and  560 , the retention configurations of both shell segment retainers involves rotation of their respective jaws from the ready configurations seen in  FIGS.  62 - 63    to the retention configurations seen in  FIG.  64   . In particular, the jaws  552  of first shell segment retainer  550  and jaws  562  of the second shell segment retainer  560  are located farther apart when in their respective ready configurations than when in their respective retention configurations (see, for example,  FIG.  64   ). 
     Although both jaws  552  of first shell segment retainer  550  and both jaws  562  of the second shell segment retainer  560  rotate when moving between their respective ready configurations and retention configurations, in one or more alternative embodiments, the respective retainer actuators used to move the shell segment retainers between their ready and retention configurations make the jaw of one or both of the first shell segment retainer  550  and second shell segment retainer  560 . 
     With reference to the depicted illustrative embodiments of the first shell segment retainer  550  and second shell segment retainer  560 , the first shell segment retainer  550  and the second shell segment retainer  560  may both be described as being located closer to the working surface  514  when in their respective retention configurations than when in their respective ready configurations. 
     Referring to  FIGS.  62 - 64   , the differences between the ready configuration and retention configuration for the first shell segment retainer  550  may be described as follows: the first shell segment retainer  550  is configured to allow for positioning of a shrimp (for example, shrimp  502 ) between the first shell segment retainer  550  and the working surface  514  when the first shell segment retainer  550  is in the ready configuration as seen in  FIGS.  62 - 63   . Further, the first shell segment retainer  550  is configured to retain the first shell segment of a shrimp (for example, shrimp  502 ) located between the first shell segment retainer  550  and the working surface  514  in a selected location on the working surface when the first shell segment retainer  550  is in its retention configuration as seen in  FIG.  64   . With respect to the depicted illustrative embodiment of first shell segment retainer  550 , it can be seen that positioning of a shrimp (for example, shrimp  502 ) between the first shell segment retainer  550  and the working surface  514  when the first shell segment retainer  550  is in its retention configuration as seen in  FIG.  64    would be difficult, if not impossible. 
     Again referring to  FIGS.  62 - 64   , the differences between the ready configuration and the retention configuration for the second shell segment retainer  560  may be described as follows: the second shell segment retainer is configured to allow for positioning of a shrimp (for example, shrimp  502 ) between the second shell segment retainer  560  and the working surface  514  when the second shell segment retainer  560  is in the ready configuration as seen in  FIGS.  62 - 63   . Further, the second shell segment retainer  560  is configured to retain a second shell segment of a shrimp (for example, shrimp  502 ) located between the second shell segment retainer  560  and the working surface  514  in a selected location relative to the second shell segment retainer  560  when the second shell segment retainer is in its retention configuration as seen in  FIG.  64   . With respect to the depicted illustrative embodiment of the second shell segment retainer  560  it can be seen that positioning of a shrimp (for example, shrimp  502 ) between the second shell segment retainer  560  and the working surface  514  when the second shell segment retainer  560  is in its retention configuration as seen in  FIG.  64    would be difficult, if not impossible. 
     Operation of the depicted illustrative embodiment of shell segment separator apparatus  540  can be discussed with reference to  FIGS.  65 - 66   .  FIG.  65    is a side view of the shell segment separator apparatus of  FIG.  64   , with the second shell segment retainer  560  in its initial position, while  FIG.  66    is a side view of the shell segment separator apparatus  540  of  FIG.  64    after the second shell segment retainer  560  has been moved from the initial position to the separation position. 
     In the depicted illustrative embodiment of shell segment separator apparatus  540 , a separation actuator is used to move the second shell segment retainer  560  from the initial position seen in  FIG.  65    to the separation position seen in  FIG.  66   . The second shell segment retainer  560  is located further away from the first shell segment retainer  550  when the second shell segment retainer  560  is in the separation position seen in  FIG.  66    than when the second shell segment retainer  560  is in the initial position seen in  FIG.  65   . As seen in  FIGS.  65 - 66   , the second shell segment retainer  560  may also be described as moving away from the clamp  512  retaining a shrimp  502  in a selected location relative to the shell segment separator apparatus  540 . The second shell segment retainer  560 , in the depicted illustrative embodiment, moves along the processing axis  511  when moving between its initial position and separation position, with the first shell segment retainer  550  and the second shell segment retainer  560  being aligned on the processing  511 . 
     As described herein, the separation actuator moves the second shell segment retainer  560  from its initial position to its separation position after operating the first shell segment retainer  550  from its ready configuration to its retention configuration and after operating the second retainer actuator to move the second shell segment retainer  560  from its ready configuration to its retention configuration. In one or more embodiments, the initial position and the separation position may be separated from each other along the processing axis  511  by a selected separation distance  566  (see  FIG.  66   ). 
     As a result, movement of the second shell segment retainer  560  to its separation position moves the shell segment retained by the second shell segment retainer  560  away from the shell segment retained by the first shell segment retainer  550 , thereby separating the two shell segments as discussed herein. That separation or movement between the two adjacent shell segments breaks or severs connections between the adjacent shell segments to allow for clean separation at the junction between the two adjacent shell segments as described herein. Separation of the adjacent shell segments is not intended to remove the adjacent shell segments from the abdomen of the shrimp. Rather, the shell segments remain attached to the abdomen of the shrimp after separation using the shell segment separation apparatus described herein. 
     In one or more embodiments, the positions of the first shell segment retainer  550  and the second shell segment retainer  560  can be described relative to the clamp  512  used to restrain a shrimp in the selected location relative to the shell segment separator apparatus  540 . For example, the first shell segment retainer  550  may be described as being located between the second shell segment retainer  560  and the clamp  512  along the processing axis  511 . In one or more embodiments, the first shell segment retainer  550  may preferably be held stationary or in a fixed position relative to the clamp  512  while the second shell segment retainer  560  is movable relative to both the first shell segment retainer  550  and the clamp  512  (using, in the depicted illustrative embodiment, the second retainer shuttle  570 ). In one or more alternative embodiments, however, the first shell segment retainer  550  may also move relative to the clamp  512  and/or the second shell segment retainer  560 . 
     Although the illustrative embodiment of the shell segment separator apparatus depicted in  FIGS.  60  and  62 - 66    includes shell segment retainers having jaws that move between the ready and retention configurations, shell segment separator apparatus described herein may not include movable jaws.  FIGS.  67 - 70    depict one alternative illustrative embodiment of a shell segment separator apparatus that does not include movable jaws. 
     The shell segment separator apparatus depicted in  FIGS.  67 - 70    includes shell segment retainers  650  and  660  positioned opposite (e.g., above) a working surface  614  along which a processing axis  611  extends. Because the shell segment retainers  650  and  660  are aligned along the processing axis  611 , only shell segment retainer  650  is visible in  FIGS.  67  and  68   . In  FIG.  67   , the shell segment retainers  650  and  660  are in the ready configuration in which the shell segment retainers  650  and  660  are spaced apart from the working surface  614  by a distance sufficient to allow for positioning of a shrimp between the shell segment retainers  650  and  660  and the working surface  614 . 
     In contrast, the shell segment retainers  650  and  660  are in their retention configurations in  FIGS.  68 - 70    such that shell segments of a shrimp positioned between the shell segment retainers  650  and  660  and the working surface  614  in a selected location on the working surface  614  are retained in the selected location. In the depicted embodiment, the shell segment retainers  650  and  660  are located closer to the working surface  614  in their retention configurations than when the shell segment retainers are in their ready configurations. 
     The depicted illustrative embodiment of shell segment retainer  650  as depicted in  FIGS.  67 - 70    includes a notch  652  configured to receive the abdomen of a shrimp such that the notch rests on or faces the dorsal surface of a shrimp in the selected location on working surface  614  with its ventral surface facing or resting on the working surface  614 . Similarly, the depicted illustrative embodiment of shell segment retainer  660  as depicted in  FIGS.  69 - 70    includes a notch  662  configured to receive the abdomen of a shrimp such that the notch  662  rests on or faces the dorsal surface of a shrimp in the selected location on working surface  614  with its ventral surface facing or resting on the working surface  614 . 
     The illustrative embodiment of shell segment retainer  650  as depicted in  FIGS.  67 - 70    also includes pins  654  positioned in the notch  652  such that the pins engage (e.g., pierce) a shell segment on the dorsal surface of a shrimp in the selected location on working surface  614  with its ventral surface facing or resting on the working surface  614 . Similarly, the depicted illustrative embodiment of shell segment retainer  660  as depicted in  FIGS.  69 - 70    also includes pins  664  positioned in the notch  662  such that the pins  664  engage (e.g., pierce) a shell segment on the dorsal surface of a shrimp in the selected location on working surface  614  with its ventral surface facing or resting on the working surface  614 . 
     The cross-sectional views of  FIGS.  69 - 70    can be used to describe movement of the shell segment retainers  650  and  660  from the initial position (see, e.g.,  FIG.  69   ) to the separation position (see, e.g.,  FIG.  70   ). In particular, the shell segment retainers  650  and  660  are closer together when in the initial position of  FIG.  69    than when in the separation position of  FIG.  70   . In other words, the distance di between the shell segment retainers  650  and  660  in the initial position of  FIG.  69    is less than the distance ds between the shell segment retainers  650  and  660  in the separation position of  FIG.  70    (or, conversely, the distance ds between the shell segment retainers  650  and  660  in the separation position of  FIG.  70    is greater than the distance di between the shell segment retainers  650  and  660  in the initial position of  FIG.  69   . 
     Although not depicted, it should be understood that yet another illustrative embodiment of a shell segment separator apparatus could include one shell segment retainer having movable jaws as depicted in, e.g.,  FIGS.  60  and  62 - 66    and one shell segment retainer including a notch and pins as depicted in, e.g.,  FIGS.  67 - 70   . 
     In terms of methods, shell segment separation may involve separating adjacent shell segments on an abdomen of a shrimp (for example, shrimp  502 ), with the method including retaining a first shell segment on an abdomen of a shrimp in a fixed location relative to a processing axis (for example, a processing axis  511 ), moving a second shell segment on the abdomen of the shrimp away from the first shell segment in a direction aligned with the processing axis while retaining the first shell segment in the fixed location. Moreover, the first and second shell segments remain attached to the abdomen of the shrimp after separation of the adjacent shell segments. 
     In one or more embodiments of the shell segment separation as described herein, the adjacent shell segments may be described as the rearmost abdominal shell segment of the shrimp (that is, the shell segment closest to the tail of the shrimp) and the adjacent shell segment located on the opposite side of the rearmost abdominal shell segment. In terms of shrimp having, for example, six abdominal shell segments, the rearmost abdominal shell segment would be the sixth shell segment, while the adjacent or second abdominal shell segment would be the fifth shell segment. In the depicted illustrative embodiment, the shell segment separator apparatus  540  holds the sixth shell segment in a fixed location using the first shell segment retainer  550  while the shell segment separator apparatus  540  moves the fifth shell segment away from the sixth shell segment using the second shell segment retainer  560 . 
     Although the shell segment separator apparatus and methods of using the same may preferably involve separation of the rearmost and adjacent shell segments, alternative embodiments of the shell segment separator apparatus and methods described herein may involve separation of any adjacent pair of shell segments on shrimp processed using the shrimp processing systems described herein. 
     Illustrative Aspects 
     Following are illustrative aspects of the shrimp heading and/or deveining apparatus and methods described herein. 
     In independent aspect A1, a mud vein severing apparatus as described herein comprises: a vein severing module comprising a blade comprising a sharpened working edge and a blade actuator configured to move the blade between a stored position and a severed position; an optional measurement module configured to measure a length of a shrimp held in a clamp moving through the measurement module along a measurement direction; a controller operably connected to the blade actuator and the optional measurement module, wherein the controller is configured to: optionally receive a signal indicative of the length of the shrimp from the measurement module; and activate the blade actuator to move the blade from the stored position to the severed position when a shrimp is in a selected severing location, wherein the blade actuator moves the blade along a severing path generally transverse to the measurement direction. 
     In aspect A2 according to aspect A1, the cutting edge of the blade comprises a curved edge. 
     In aspect A3 according to any one of aspects A1 to A2, the cutting edge of the blade faces away from the ventral side of a shrimp in the selected severing location as the blade moves along the severing path. 
     In aspect A4 according to any one of aspects A1 to A3, the severing path comprises a rectilinear path. 
     In aspect A5 according to any one of aspects A1 to A4, the vein severing module comprises a severing restraint configured to fix a position of a shrimp held in a clamp, wherein the severing restraint is operably attached to a severing restraint actuator configured to move the severing restraint between a withdrawn position and a restraint position, wherein a shrimp held in a clamp in the selected severing location is restrained by the severing restraint when the severing restraint is in the restraint position, and wherein the severing restraint actuator is operably connected to the controller, wherein the controller is configured to operate the severing restraint actuator to move the severing restraint to the restraint position when a shrimp held in a clamp is in the selected severing location and before the blade actuator is operated to move the blade along the severing path. 
     In aspect A6 according to aspect A5, the severing restraint is located between the blade and the clamp when a shrimp held in a clamp is in the selected severing location and the severing restraint is in the restraint position. 
     In aspect A7 according to any one of aspects A5 to A6, the restraint actuator comprises a force limited actuator configured to apply a selected force to a shrimp through the severing restraint when the severing restraint is in the restraint position. 
     In aspect A8 according to any one of aspects A5 to A7, a position of the severing path is fixed relative to the severing restraint such that the severing restraint is configured to set a position of the blade relative to a shrimp held in a clamp in the selected severing location when the severing restraint is in the restraint position. 
     In aspect A9 according to any one of aspects A5 to A8, the severing restraint comprises a notch, and wherein the notch is configured to contact a dorsal side of a shrimp held in a clamp in the selected severing location, wherein the position of the severing path is fixed relative to the notch. 
     In aspect A10 according to aspect A9, the notch comprises a beveled surface extending from a tail side of the severing restraint to a carapace side of the restraint, and wherein the notch is larger on the carapace side of the severing restraint than on the tail side of the severing restraint. 
     In aspect A11 according to any one of aspects A5 to A10, the controller is configured to operate the blade actuator to return the blade to the stored position from the severed position before operating the severing restraint actuator to return the severing restraint to the withdrawn position after operating the blade actuator to move the blade from the stored position to the severed position. 
     In aspect A12 according to any one of aspects A1 to A11, the vein severing module comprises a vein severing module drive configured to move the blade and the blade actuator along the measuring direction, wherein the vein severing module drive is operably connected to the controller, and wherein the controller is configured to operate the vein severing module to adjust a position of the blade along the measuring direction before actuating the blade actuator. 
     In any embodiments of the mud vein severing apparatus, the controller is configured to operate the vein severing module to adjust a position of the blade along the measuring direction based at least in part on the length of the shrimp. 
     In aspect A13 according to any one of aspects A1 to A12, the measurement module comprises a non-contact sensor configured to detect the clamp and a shrimp held in the clamp, the non-contact sensor operably connected to the controller to deliver signals indicative of energy received by the non-contact sensor, wherein the controller is configured to: identify a junction between a clamp and a shrimp held in the clamp when moving a shrimp held in the clamp through the non-contact sensor based on a signal received from the non-contact sensor; determine a length of a shrimp held in a clamp after identifying the junction between a clamp and a shrimp held in a clamp based at least in part on a signal received from the non-contact sensor; and optionally, determine a weight of a shrimp held in a clamp after determining the length of a shrimp held in a clamp based at least in part on the length of a shrimp held in a clamp. 
     In aspect A14 according to aspect A13, the controller is configured to identify a junction between a clamp and a shrimp when the signal received from the non-contact sensor reaches or falls below a selected clamp threshold value. 
     In aspect A15 according to any one of aspects A13 to A14, the controller is configured to determine a length of a shrimp when the signal received from the non-contact sensor reaches or exceeds a selected antenna threshold value. 
     In aspect A16 according to any one of aspects A13 to A15, the non-contact sensor comprises an optical sensor or an ultrasonic sensor. 
     In aspect A17 according to any one of aspects A13 to A16, the controller is configured to operate the non-contact sensor to calibrate the non-contact sensor before every shrimp held in a clamp passes through the non-contact sensor in the measurement direction. 
     In aspect A18 according to any one of aspects A13 to A16, the controller is configured to operate the non-contact sensor to calibrate the non-contact sensor after a selected number of shrimp held in a clamp pass through the non-contact sensor in the measurement direction. 
     Independent aspect B0 comprises a method of severing a vein of a shrimp using an apparatus according to any one of aspects A1 to A18. 
     In independent aspect B1, a method of severing a mud vein of a shrimp comprises: positioning a shrimp in a selected severing location; and moving a blade through the shrimp along a severing path oriented generally transverse to a length of the shrimp as measured from a carapace to a tail of the shrimp, wherein the blade passes through a shell of the shrimp at a selected depth proximate a junction between a rearmost abdominal shell segment and an adjacent abdominal shell segment of the shrimp, wherein the rearmost abdominal shell segment is located between the adjacent abdominal shell segment and the tail of the shrimp. 
     In aspect B2 according to aspect B1, the method comprises determining a position of the junction between the rearmost abdominal shell segment and the adjacent abdominal shell segment of the shrimp based at least in part on a length of the shrimp. 
     In aspect B3 according to any one of aspects B1 to B2, the method comprises measuring the length of the shrimp before moving the blade through the shrimp. 
     In aspect B4 according to any one of aspects B1 to B3, a cutting edge of the blade faces a dorsal surface of the shrimp and away from a ventral surface of the shrimp. In aspect B5 according to aspect B4, the cutting edge of the blade is curved along a length of the blade. 
     In aspect B6 according to any one of aspects B1 to B5, the severing path comprises a rectilinear path. 
     In aspect B7 according to any one of aspects B1 to B6, the method further comprises adjusting a position of the blade along the length of the shrimp such that the blade passes through the shrimp at a location proximate the junction between the between the rearmost abdominal shell segment and the adjacent abdominal shell segment of the shrimp when the blade moves through the shrimp along the severing path. In aspect B8 according to aspect B7, adjusting the position of the blade comprises adjusting the position of the blade at least in part based on a measured length of the shrimp. 
     In aspect B9 according to any one of aspects B1 to B8, the method further comprises determining a height of the dorsal surface of the shrimp proximate the junction between the rearmost abdominal shell segment and the adjacent abdominal shell segment before moving the blade through the shrimp. In aspect B10 according to aspect B9, determining the height of the dorsal surface of the shrimp proximate the junction between the rearmost abdominal shell segment and the adjacent abdominal shell segment comprises contacting a dorsal surface of the rearmost shell segment with a shrimp restraint before moving the blade through the shrimp. In aspect B11 according to aspect B10, a location of the severing path is fixed relative to the shrimp restraint. In aspect B12 according to aspect B11, the shrimp restraint comprises a notch, and wherein the method comprises restraining the shrimp from movement in a direction aligned with the severing path. 
     In aspect B13 according to any one of aspects B10 to B12, the method comprises forcing the shrimp restraint against the dorsal surface of the shrimp with a force-limited actuator. 
     In aspect B14 according to any one of aspects B1 to B13, the method comprises restraining the shrimp from movement in a direction aligned with the severing path before moving the blade through the shrimp along the severing path. In aspect B15 according to aspect B14, moving the blade through the shrimp along the severing path comprises moving the blade from a stored position to a severed position, and wherein the method comprises returning the blade back to the stored position from the severed position after moving the blade through the shrimp from the stored position to the severed position along the severing path. In aspect B16 according to aspect B15, returning the blade back to the stored position from the severed position comprises moving the blade along the severing path. 
     In aspect B17 according to any one of aspects B14 to B16, the method comprises restraining the shrimp from movement in a direction aligned with the severing path while returning the blade back to the stored position from the severed position. 
     In independent aspect C1, a shrimp heading apparatus comprises: a heading restraint positioned opposite a working surface; a heading restraint actuator configured to move the heading restraint between a stored position and restraint position relative to the working surface, wherein the heading restraint is spaced from the working surface to allow for positioning of a shrimp between the heading restraint and the working surface when the heading restraint is in the stored position, and wherein the heading restraint is closer to the working surface when the heading restraint is in the restraint position than when the heading restraint is in the stored position such that the heading restraint is configured to force a shrimp located between the heading restraint and the working surface against the working surface when the heading restraint is in the restraint position; a spoon; a spoon actuator configured to move the spoon along a spoon path between a ready position and finish position relative to the heading restraint, wherein a working portion of the spoon is proximate a carapace side of the heading restraint when the spoon is in the ready position and wherein the working portion of the spoon is spaced away from the carapace side of the heading restraint when the spoon is in the finish position such that the working portion of the spoon is configured to separate a head of a shrimp on the working surface from an abdomen of the shrimp when the spoon moves from the ready position to the finish position; and a controller operably connected to the heading restraint actuator and the spoon actuator, the controller configured to: operate the heading restraint actuator to move the heading restraint from the stored position to the restraint position, operate the spoon actuator to move the spoon along the spoon path from the ready position to the finish position after operating the head restraint actuator to move the heading restraint to the restraint position, and operate the heading restraint actuator to return the heading restraint to the stored position after operating the spoon actuator to move the spoon to the finish position. 
     In aspect C2 according to aspect C1, the controller is configured to operate the spoon actuator to return the spoon to the ready position after operating the head restraint actuator to return the heading restraint to the stored position. 
     In aspect C3 according to aspect C1, the controller is configured to operate the spoon actuator to return the spoon to the ready position before operating the head restraint actuator to return the heading restraint to the stored position. 
     In aspect C4 according to any one of aspects C1 to C3, the heading restraint actuator comprises a force-limited actuator configured to apply a compressive restraint force up to a selected restraint force limit on a shrimp located on the working surface between the heading restraint and the working surface. 
     In aspect C5 according to any one of aspects C1 to C4, the spoon actuator comprises a velocity-limited actuator configured to move the working portion of the spoon from the ready position to the finish position at a selected maximum velocity. 
     In aspect C6 according to any one of aspects C1 to C5, the working portion of the spoon moves closer to the working surface while moving along the spoon path after leaving the ready position than when the working portion of the spoon is in the ready position. In aspect C7 according to aspect C6, the working portion of the spoon is closest to the working surface when the working portion of the spoon is at a selected location along the spoon path that is between the ready position and the finish position. 
     In aspect C8 according to any one of aspects C1 to C7, the working portion of the spoon comprises a spoon notch comprising a spoon notch opening facing the working surface when the spoon is in the ready position and the heading restraint is in the restraint position. In aspect C9 according to aspect C8, the heading restraint comprises a restraint notch, wherein a restraint notch opening of the restraint notch faces the working surface and any shrimp located between the restraint notch and the working surface, and wherein the spoon notch is aligned with and adjacent the restraint notch when the working portion of the spoon is in the ready position. In aspect C10 according to any one of aspects C8 to C9, when the heading restraint is in the restraint position, the spoon notch has a depth measured from the working surface to a spoon notch end distal from the working surface that is sufficient to clear a mud vein of a shrimp located on the working surface between the heading restraint and the working surface such that the spoon does not sever the mud vein. In aspect C11 according to any one of aspects C8 to C10, the spoon notch is wider in a direction transverse to the spoon path at the spoon notch opening than at a spoon notch end of the spoon notch located distal from the working surface. In aspect C12 according to any one of aspects C8 to C11, when the heading restraint is in the restraint position and the working portion of the spoon is in the ready position, the spoon notch has a depth measured from the working surface to a spoon notch end distal from the working surface that is 10 millimeters or more, and, optionally, wherein the depth of the spoon notch is 20 millimeters or less. 
     In aspect C13 according to any one of aspects C1 to C12, the heading restraint defines a contact portion configured to contact a shrimp located on the working surface between the contact portion and the working surface when the heading restraint is in the restraint position, and wherein the heading restraint comprises a guide extending away from the contact portion, wherein a head of a shrimp located on the working surface between the contact portion and the working surface when the heading restraint is in the restraint position is located within the guide of the heading restraint, and wherein the working portion of the spoon moves away from the contact portion and past the guide when moving from the ready position to the finish position. In aspect C14 according to aspect C13, the guide comprises a pair of wings defining a channel between the pair of wings, wherein a head of a shrimp located on the working surface between the contact portion and the working surface when the heading restraint is in the restraint position is located in the channel between the pair of wings, and wherein the working portion of the spoon moves between the pair of wings during at least a portion of a path of the working portion of the spoon when the spoon moves from the ready position to the finish position. In aspect C15 according to any one of aspects C13 to C14, the working portion of the spoon comprises a spoon width that is less than a guide width of the guide, wherein the spoon width and the guide width are measured transverse to the spoon path. In aspect C16 according to aspect C15, the maximum width of the working portion of the spoon as measured within the guide is 50% or more, 60% or more, 70% or more, 80% or more, or 90% of the guide width. 
     In aspect C17 according to any one of aspects C1 to C16, the working portion of the spoon comprises a beveled outer edge. 
     In aspect C18 according to any one of aspects C1 to C16, the heading restraint comprises a beveled edge facing the working surface when the heading restraint is in the restraint position. 
     In aspect C19 according to any one of aspects C1 to C16, the working portion of the spoon comprises a beveled outer edge and the heading restraint comprises a beveled edge facing the working surface when the heading restraint is in the restraint position, wherein the beveled outer edge of the working portion of the spoon and the beveled edge of the heading restraint are adjacent each other when the spoon is in the ready position such that bevels on the beveled outer edge of the working portion of the spoon and the beveled edge of the heading restraint face away from each other, wherein the working portion of the spoon and the heading restraint form a double bevel edge when the spoon is in the ready position. 
     In aspect C20 according to any one of aspects C1 to C19, the heading apparatus comprises a carapace sensor operably connected to the controller, the carapace sensor configured to detect a carapace junction between a carapace and an abdominal segment of a shrimp on the working surface. In aspect C21 according to aspect C20, the controller is configured to detect a change in opacity between a carapace and an abdominal segment of a shrimp on the working surface and identify the carapace junction based, at least in part, on the change in opacity. In aspect C22 according to any one of aspects C20 to C21, the heading apparatus comprises a heading restraint locator operably connected to the controller, wherein the controller is configured to operate the heading restraint locator to position the heading restraint on a first abdominal segment of a shrimp on the working surface adjacent the carapace junction when the heading restraint is in the restraint position on a shrimp on the working surface. 
     In aspect C23 according to aspect C22, the controller is configured to calibrate the carapace sensor on an abdominal segment of a shrimp on the working surface before operating the heading restraint locator to position the heading restraint on the first abdominal segment of a shrimp on the working surface. 
     In aspect C24 according to aspect C22, the controller is configured to calibrate the carapace sensor on an abdominal segment of a shrimp on the working surface after moving the heading restraint to the stored position and before operating the heading restraint locator to position the heading restraint on the first abdominal segment of a shrimp on the working surface. 
     In aspect C25 according to any one of aspects C20 to C24, the heading apparatus comprises a spoon locator operably connected to the controller, wherein the controller is configured to operate the spoon locator to position the spoon such that the spoon contacts a shrimp on the working surface proximate the carapace junction on a carapace side of the heading restraint when the heading restraint is in the restraint position on a shrimp on the working surface and the spoon is moving towards the working surface from the ready position. 
     In aspect C26 according to aspect C25, the controller is configured to calibrate the carapace sensor on an abdominal segment of a shrimp on the working surface before operating the spoon locator to position the spoon such that the spoon contacts a shrimp on the working surface proximate the carapace junction on a carapace side of the heading restraint when the heading restraint is in the restraint position on a shrimp on the working surface and the spoon is moving towards the working surface from the ready position. 
     In aspect C27 according to any one of aspects C25 to C26, the controller is configured to calibrate the carapace sensor on an abdominal segment of a shrimp on the working surface after moving the spoon to the ready position and before operating the spoon locator to position the spoon such that the spoon contacts a shrimp on the working surface proximate the carapace junction on a carapace side of the heading restraint when the heading restraint is in the restraint position on a shrimp on the working surface and the spoon is moving towards the working surface from the ready position 
     In aspect C28 according to any one of aspects C20 to C27, the heading apparatus comprises a heading apparatus shuttle and a shuttle actuator configured to move the heading apparatus shuttle, wherein the shuttle actuator is operably connected to the controller, wherein the heading restraint, heading restraint actuator, spoon, and spoon actuator are mounted on the heading apparatus shuttle, and wherein the controller is configured to operate the shuttle actuator to position the heading apparatus shuttle such that the heading restraint is positioned on a first abdominal segment of a shrimp on the working surface adjacent the carapace junction when the heading restraint is in the restraint position on a shrimp on the working surface and such that the spoon contacts a shrimp on the working surface proximate the carapace junction on a carapace side of the heading restraint when the heading restraint is in the restraint position on a shrimp on the working surface and the working portion of the spoon is moving towards the working surface from the ready position. In aspect C29 according to aspect C28, the carapace sensor is mounted on the heading apparatus shuttle. 
     In aspect C30 according to any one of aspects C28 to C29, the controller is configured to calibrate the carapace sensor on an abdominal segment of a shrimp on the working surface before operating the shuttle actuator to position the heading apparatus shuttle such that the heading restraint is positioned on a first abdominal segment of a shrimp on the working surface adjacent the carapace junction when the heading restraint is in the restraint position on a shrimp on the working surface and such that the working portion of the spoon contacts a shrimp on the working surface proximate the carapace junction on a carapace side of the heading restraint when the heading restraint is in the restraint position on a shrimp on the working surface and the working portion of the spoon is moving towards the working surface from the ready position. 
     In aspect C31 according to any one of aspects C1 to C30, the spoon actuator comprises a hydraulically damped pneumatic actuator comprising: a main piston and a floating piston located within an actuator housing; a main piston port in fluid communication with a main piston volume located in the actuator housing; a floating piston port in fluid communication with a floating piston volume located in the actuator housing; a working piston volume located in the actuator housing between the main piston and the floating piston; and a flow control orifice and damping liquid in the working piston volume, wherein the flow control orifice separates the working piston volume into a main portion and a floating portion; wherein fluid introduced into the main piston volume through the main piston port when at least a portion of the damping liquid is located in the main portion of the working piston volume forces the damping liquid out of the main portion into the floating portion through the flow control orifice to move the floating piston in a first direction relative to the actuator housing; and wherein fluid introduced into the floating piston volume through the floating piston port when at least a portion of the damping liquid is located in the floating portion of the working piston volume forces the damping liquid out of the floating portion into the main portion through the flow control orifice to move the floating piston in a second direction relative to the actuator housing, wherein the first direction is opposite from the second direction. 
     In aspect C32 according to aspect C31, the flow control orifice consists essentially of an opening through which the damping liquid passes when moving between the main portion and the floating portion of the working volume. In aspect C33 according to aspect C31, the flow control orifice comprises a needle valve. 
     In aspect C34 according to any one of aspects C31 to C33, the main piston volume comprises a maximum main piston volume that is greater than a volume of the damping liquid in the working piston volume. 
     In aspect C35 according to any one of aspects C31 to C33, the floating piston volume comprises a maximum floating piston volume that is greater than a volume of the damping liquid in the working piston volume. 
     In aspect C36 according to any one of aspects C31 to C33, the main piston volume comprises a maximum main piston volume that is greater than a volume of the damping liquid in the working piston volume; and wherein the floating piston volume comprises a maximum floating piston volume that is greater than the volume of the damping liquid in the working piston volume. 
     In independent aspect D1, one or more embodiments of methods of removing a head of a shrimp comprise: restraining an abdomen of a shrimp in a fixed position on a working surface; moving a spoon through the shrimp proximate a carapace junction of the shrimp, wherein the carapace junction is located between a carapace and a first abdominal segment of the shrimp; and moving the spoon away from the abdomen while restraining the abdomen of the shrimp in the fixed position on the working surface, wherein moving the spoon away from the abdomen separates the carapace of the shrimp from the abdomen of the shrimp. 
     In aspect D2 according to aspect D1, restraining an abdomen comprises forcing the abdomen against the working surface using a heading restraint, wherein the abdomen is located between the heading restraint and the working surface. In aspect D3 according to aspect D2, restraining an abdomen comprises forcing the abdomen against the working surface by moving a heading restraint towards the working surface. 
     In aspect D4 according to any one of aspects D1 to D3, restraining an abdomen comprises restraining a first abdominal segment of the abdomen of the shrimp, wherein the first abdominal segment is immediately adjacent the carapace of the shrimp. In aspect D5 according to aspect D4, the method further comprises determining the location of the carapace junction before restraining the first abdominal segment of the shrimp. In aspect D6 according to aspect D5, determining the location of the carapace junction comprises optically detecting the carapace junction. 
     In aspect D7 according to any one of aspects D5 to D6, determining the location of the carapace junction comprises detecting the carapace junction using a carapace sensor, and wherein the method comprises calibrating the carapace sensor on an abdominal segment of the abdomen before detecting the carapace junction. In aspect D8 according to aspect D7, for each shrimp of a plurality of shrimp, the method comprises calibrating the carapace sensor on an abdominal segment of the before detecting the carapace junction. 
     In aspect D9 according to any one of aspects D1 to D8, moving the spoon away from the abdomen comprises moving a working portion of the spoon along a spoon path that is arcuate over at least a portion of the spoon path. In aspect D10 according to aspect D9, the working portion of the spoon moves closer to the working surface as the spoon moves away from the abdomen of the shrimp. 
     In aspect D11 according to any one of aspects D1 to D10, the method comprises moving the spoon away from the abdomen restrained in the fixed position after moving the spoon through the shrimp. 
     In aspect D12 according to any one of aspects D1 to D11, moving the spoon away from the abdomen restrained in the fixed position comprises removing a mud vein from the shrimp while moving the spoon away from the abdominal segment. 
     In aspect D13 according to aspect D12, the method comprises severing the mud vein of the shrimp before moving the spoon away from the abdominal segment. In aspect D  14  according to aspect D13, severing the mud vein comprises severing the mud vein at a selected location closer to a tail of the shrimp than the carapace of the shrimp. In aspect D15 according to aspect D14, the selected location is proximate a junction between a rearmost abdominal shell segment and an adjacent abdominal shell segment of the shrimp, wherein the rearmost abdominal shell segment is located between the adjacent abdominal shell segment and the tail of the shrimp. 
     In aspect D16 according to any one of aspects D13 to D15, severing the mud vein comprises moving a blade through the shrimp along a severing direction, wherein the blade passes through a shell of the shrimp at a selected depth, and wherein the severing direction is generally transverse to a length of the shrimp as measured between the carapace and the tail of the shrimp. 
     In aspect D17 according to any one of aspects D15 to D16, the method comprises determining a position of the junction between the rearmost abdominal shell segment and the adjacent abdominal shell segment of the shrimp based at least in part on a length of the shrimp. In aspect D18 according to aspect D17, the method comprises measuring a length of the shrimp before moving severing the mud vein. 
     In aspect D19 according to any one of aspects D16 to D18, the method further comprises determining a height of the shell proximate the junction between the fifth and sixth shell segments before moving the blade through the shrimp at the selected depth. 
     Any references and publications cited herein are expressly incorporated herein by reference in their entirety into this disclosure, except to the extent they may directly contradict this disclosure. Although specific illustrative embodiments have been described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. It should be understood that this disclosure is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only with the scope of the disclosure intended to be limited only by the claims.