Dragon Anatomy

This document is intended as an aid to Dragonhealing, and should supplement reading of 'The Dragonlover's Guide to Pern' by Jody Lynn Nye with Anne McCaffrey and the 'DragonRider's of Pern' series of books by Anne McCaffrey.
Whenever new information is available, this document will be updated, but in the meantime please feel free to email the author with any questions or further details.
==Endoskeleton==
'In Character' little information is known about the internal systems of Dragons since terminally injured Dragons go between, so please remember this when reading this document and roleplaying.
==Endoskeleton
==
Dragon bones are not easily broken unlike a human. The design buffers takeoffs and landings effectively, and animal meat (which on Pern contains Boron) sustains skeletal strength, much like humans require milk products (for the calcium). They have a stronger endoskeleton (outer skeleton) than us and so, despite their size and form, are comfortable upright. The skeleton itself is constructed of light flexible plates that are designed to glide over each over. A modified ball and socket joint in their hips prevents their knees from dislocating during the powerful thrusts needed for takeoff and during the absorption of impact on landing.
The ribcage of a Dragon is comprised of a single piece, unlike a human, and is surprisingly large. Despite being constructed from a single piece, ribcages rise and fall, and thus some muscles and ligaments must allow for this, probably a huge diaphragm. Dragons chests can double in size upon full inflation, presumably to deal with working under pressure and at altitude.
A Dragon wing is particularly complicated, comprised of many bones which allow it to extend, flex and furl. The easiest way to describe the skeleton of a Dragon wing is to consider the structure of a sail on a boat or a modified human arm. Two wingbones extend outward from the shoulder joint, running almost in series to each other, but separated by the 'elbow', the bones forming the 'lub'. These wingbones conclude in the finger joints, where the spar bone forms the outer edge of the wing. The mid-bone and inner-bone also extend outwards from the finger joint, sometimes known as a wingspar or pinion, jointed themselves several times, like the spar bone, to provide flexibility (see Wing Structure for further information).
Muscular Representation ©
Dragons are heavily muscled, their back legs in particular are massive, enabling them to leap far off the ground on takeoff. In appearance the muscles glisten silver-grey in colour, with the grey becoming darker, and greener, where the ichor supply is richer.
Dragon forelegs are much shorter than their rear limbs, appearing more like modified arms than legs, and the shortness lends them an ungainly hop-skip movement when walking. Therefore, they have a tendency to relax in an upright, 'sitting' position. Firelizards limbs are more equal in length and musculature than Dragons, which means they spend less time in an upright position.
Dragons have pentadactyl (five-fingered) claws, jointed much like a human's hand to allow adequate purchase. On the other hand, Watch Whers only have two claws instead of the five, with a single pad on which to rest their weight on. Long, sharp talons are found on the front limbs, which are excellent for hunting. The rear limbs have softer nails, but these are still stronger than humans'. Dragon talons are similar in nature to canine claws, and even our own fingernails. They are made of keratin, and grow out from a talon bed, which is situated in the foot pad. Thus, the talon itself has no nerves associated with it, and therefore no feeling, until it reaches the point where it grows from the talon bed. There it is nourished with ichor and nerves. However, that's not to say they cannot feel by association through their talons, though it is more correct to say that they feel the connection through the talon to the talon bed.
==Exoskeleton==
Dragonhide is not metallic in nature, neither is it constructed of 'scales'. It is extremely resilient to most abrasive injuries, and is smooth, soft to the touch and hairless. Healthy hide is glossy, with no hint of grey underlying the main colour and needs to be constantly cleaned and oiled, otherwise dry, patchy spots may develop, which may crack on trips between and cause great pain.
Dragonhide epidermis is known to be thick and extremely resilient to most abrasive injuries and provides, like human skin, a barrier to infection. However, absorption of topical substances is still possible. For example, Numbweed will numb the outer area in around three seconds, though it takes a little longer to penetrate the epidermis to the germative layer and thus dissipate the pain.
Female Dragons often experience a change in colour tone before they rise to mate. They may even appear to glow. The colour change differs in golds and greens. In greens it can occur up to a full day before she rises, golds on the other hand rarely show a colour change until they are ready to mate (see Mating Flights for further information). Male Dragons do not generally experience a fluctuation in colour, although their hides may deepen in colour with age and become wisped with grey (see Maturity for further information).
==Internal Systems==
Although their body temperature (35°C) is slightly cooler than humans (37°C), Dragons are definitely warm 'blooded', this can be determined by their reaction to hot and cold temperatures. However, they do not have blood and it is not even red in colour. Instead they have ichor which is dark green in colour. Ichor, like blood, is also based on a metal, in this case the metal being copper instead of iron. Dragon flesh does therefore have a green tinge to it instead of pink normally associated with humans.
Ichor circulates around the Dragon in a continuous cycle, pumped by the rhythmic contraction/relaxation, or beat, of the heart muscles. The typical lub-dub of the hearts are due to first the atria (upper heart chambers) filling with ichor, and then the contraction of the atrium muscles filling the ventricles (lower heart chamber). This, however, is a further complication in a Dragon that has multiple hearts. Since Dragon carcasses are not readily available the exact number of the hearts is unknown. The reason for multiple hearts has never been discerned, but it is thought that this may be due to the effects of altitude and exertion during mating flights and Threadfall.
The ichor circulates within a network of flexible tubes known as ichor vessels, of which there are three types. Arteries are strong, muscular, elastic-walled vessels that carry ichor away from the hearts and towards the tissues. Veins are thin-walled and carry ichor back to the heart. Ichor is squeezed through the veins by the action of the surrounding muscle and is kept flowing towards the hearts by one-way valves. Capillaries are the smallest ichor vessels and bridge the gap from arteries to veins. The force, with which the hearts pumps the ichor through these vessels, and around the body, is known as the 'ichor pressure'.
Dragons can inflate their dorsally-placed lung sacs to approximately twice their normally inflated size. Presumably this is to aid respiration under pressure at altitude and additionally may have a role in sustaining a constant flame. Since Dragon rib cages do not have the separate bones that humans do, they rely solely on the diaphragm and not on that and the intercostal muscles. The diaphragm of a Dragon is a huge band of muscle that pulls the lungs down, similar to a human, and into the ribcage, or pushes the lungs up, allowing air to move into and out of the lungs respectively. Curiously, they also snore, despite reports from Riders that suggest otherwise. This tends to be particularly prevalent within Weyrling Dragons. This is thought to be due to the fat to muscle content, which eventually levels out as they begin to eat less, and exercise more.
Dragon's tongues are not forked, and they have little saliva: just barely enough to protect from infection, and assist in masticating food and Firestone. Too much saliva would result in complications to the later reactions in the second stomach upon chewing Firestone.
Dragon teeth are strong and therefore difficult to break, a fortunate occurrence since they appear to have only one set. Age may weaken them, and therefore older Dragons may break teeth when chewing bones or Firestone. They are sharp at the front, canines, for hunting, useful for ripping and rendering, and more molar like at the back of the mouth for chewing Firestone and meat.
Dragons have two stomachs, one is for food, and the digestion of such, the other is for Firestone, and the complex reaction that is necessary in order to generate flame. Early on Dragons learn to concentrate on their second stomach when chewing Firestone. Ingestion of Firestone, and passage into the second stomach, initialises a complex chemical reaction, catalyzed by an acid. Once the chemical reaction has been completed in this second stomach, then a number of flammable gases are produced, which, when belched forth, ignite on contact with air. An experienced Dragon can sustain a flame for well over a minute and flame range can be varied from around 6 to 2 metres. Dragons disgorge the ash when they go between.
A digestive tract for the second stomach does not exist, unlike for the first which passes to the tail. Therefore, the Firestone, which has been masticated and subsequently digested inside the second stomach to an odourous ash, is not excreted but disgorged. As Weyrlings, Dragons regurgitate in ashpits near the Weyrling barracks, but once between training is underway, Dragons will disgorge the contents of their second stomach between. They may also be asked by the Holder's to disgorge contents for use as fertiliser.
Golds do not ingest Firestone; the weyrwomen therefore use Flamethrowers in Threadfall, which have as much variation in range as a Dragon. However, since gold Firelizards ingest Firestone, flame and still bear live clutches, it is believed there is something in the genetic makeup of a green Dragon that makes her sterile, and not the Firestone. Considering the frequency at which greens rise, this is somewhat of a relief to any Weyr, but no weyrwoman would consider testing this theory.
==Wing Structure==
The wingspan of a Dragon is typically 1 and 2/3s their length and, because the wings function somewhat like sails, the terms used are quite similar. Whers have short stubby malformed wings, and are incapable of flight. Approximately half the length of the wing is supported by bones that are reminiscent of a human arm between the shoulder and finger joint, including an elbow.
Two wingbones extend outward from the shoulder joint, running almost in series to each other, but separated by the 'elbow', the bones forming the 'lub' portion of the wing. It is the inherent strength of the shoulder and upper arm muscles that provides the necessary power for a downstroke of the wing, with the elbow usually held in a slightly flexed position. The lower arm terminates in the finger joint, and a membrane that stretches from here to the shoulder is known at the leading edge, whilst the one that extends from the arm and finger joint to the leech is known as the trailing edge. One of the bones at the finger joint, the spar bone, forms the outer edge of the wing, running down to the outermost, or forestay, tip, of the wing. The mid-bone and inner-bone also extend outwards from the finger joint, jointed themselves several times, like the spar bone, and provide excellent flexibility.
The finger joint is constructed in a similar fashion to our hands, and includes the metacarpals (what are known to us as the hand bones), a vestigial (unused) 'thumb' and all the joints for the wing bones. The muscles responsible for extending (extensor) and flexing (flexor) the wings start just below the elbow, narrowing into long tendons as the reach the finger joint. Additionally, they extend along all the wingbones and are attached at each joint, allowing fine control of the wingtips.
There are three membranes that make up the wing: the primary mainsail, the secondary mainsail and the spar mainsail. The primary mainsail stretches from the dorsal spine and shoulder, stretching to the inner bone and forms that largest of the three membranes that comprises the wing. It is this membrane that supports the majority of the body weight. The secondary mainsail extends from the inner bone to the mid bone, whilst the third mainsail, the spar mainsail, runs from the mid bone to the spar bone. As well as providing support of the body's weight, these latter two mainsails provide manoeuvrability. The membranes can be manipulated by the tendons attached to the various joints, to provide movement in both the horizontal and vertical planes. The outermost tip of the spar mainsail is termed the 'finger sail' since it is able to function almost independently of all the other mainsails.
The wing membranes are nearly translucent in Dragons, although thicker over the bones and muscle attachment points. However, they are significantly stronger than they appear. Additional support of the primary mainsail is provided by a number of cartilages which extend from the arm and finger joint towards the trailing edge and referred to as 'batten ribs'.
==Senses==
Dragons have known to have the share the same five senses that we do, those of sight, sound, taste, touch and smell, which are all present in different stages of development. In addition they have a sixth, and highly developed, sense, that of telepathy.
Dragons have no ears, their headknobs appearing to fulfill this function as they do react to noises that are not related to their sixth sense. Watch Whers also have headknobs that they use as audio receptors, however, their primary mode of communication is telepathic.
Dragons do not have eyelashes, their eyes being protected both by prominent eyeridges and by three sets of lids: an inner transparent pair, and two increasingly thicker sets of membranes, the outer set similar in tone to their hide colour. Dragon eyes protrude outwards from their eyesockets, and as such provide peripheral vision that extends additionally to what is above them, a useful tool in Threadfall. Dragons can, if the pairing between the Rider and Dragon has been sufficiently developed, use their Rider's eyes to see something if they are not present themselves. This bond, usually developed in Weyrlinghood can be strengthened by forcing the Rider to rely on Dragonsight, and likewise with Dragon to Rider.
Dragon eyes are multifaceted, and the whirling, that is generally associated with emotion intensity, is in fact an optical illusion caused by these facets. Eye colour reflects mood: green and blue signify contentment, yellow indicates fear, reddish orange signal anger, red expresses hunger, white denotes danger and purple suggests the mating urge and love. Additionally, Dragons, like whers, can see in the dark. Watchwhers, though, while having excellent sight even in total darkness, are photophobic, and have poor focal length. Dragons on the other hand have good focal length, being able to see objects on the ground from at least several Dragonlengths above ground, if not further.
Smell is poorly developed within Dragons. They cannot smell anything distasteful in the stench of Firestone, but can, however, smell well enough to detect 'strange' and unfamiliar scents. Sensitivity to touch seems to vary as it does in a human, with Dragon bellies having been noted as ticklish.
Dragon tongues are not forked and their teeth are strong. Their front teeth are extremely sharp, ideal for hunting, whilst their back teeth are more molar-like, perfect for chewing Firestone. Little is said about taste. However, taste buds probably do exist, but aren't that well developed, certainly not as much as a human, and detecting sweet from sour is almost certainly impossible. The ability to discern between food and Firestone to direct it to the correct stomach (seeInternal Systems for further information) does exist, but whether it is texture or taste is hard to identify.
Their sixth sense, that of telepathy, is highly developed, and they are able to bespeak any person should they choose to do so. Dragons also have an excellent spatial sense. This is particularly useful when emerging and going between and is the reason why they don't collide with others Dragons when arriving into a crowded airspace.
==Tail==
Dragons have forked tails, almost arrowhead in shape. Their sphincters are located towards the base of the tail, and excreta is stored up for several days here until they are able to go between and get rid of it. Weyrlings and infirm Dragons that cannot go between need to have their Rider muck out their couch or Weyr.
Dragon genitalia are concealed behind pouchlike flaps of hide under the junction of tail and body, and are only revealed during mating.
Category:Anatomy
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