DOI: 10.5061/dryad.3n5tb2rf7
title: Scaling and development of elastic mechanisms: the tiny strikes of larval mantis shrimp

description: Latch-mediated spring actuation (LaMSA) is used by small organisms to
 produce high acceleration movements. Mathematical models predict that
 acceleration increases as LaMSA systems decrease in size. Adult mantis
 shrimp use a LaMSA mechanism in their raptorial appendages to produce
 extremely fast strikes. Until now, however, it was unclear whether mantis
 shrimp at earlier life-history stages also strike using elastic recoil and
 latch mediation. We tested whether larval mantis shrimp (Gonodactylaceus
 falcatus) use LaMSA and, because of their smaller size, achieve higher
 strike accelerations than adults of other mantis shrimp species. Based on
 microscopy and kinematic analyses, we discovered that larval G. falcatus
 possess the components of, and actively use, LaMSA during their fourth
 larval stage, which is the stage of development when larvae begin feeding.
 Larvae performed strikes at high acceleration and speed (mean: 4.133×105
 rad s−2, 292.7 rad s−1; 12 individuals, 25 strikes), which are of the same
 order of magnitude as for adults – even though adult appendages are up to
 two orders of magnitude longer. Larval strike speed (mean: 0.385 m s−1)
 exceeded the maximum swimming speed of similarly sized organisms from
 other species by several orders of magnitude. These findings establish the
 developmental timing and scaling of the mantis shrimp LaMSA mechanism and
 provide insights into the kinematic consequences of scaling limits in tiny
 elastic mechanisms.
description: Larval mantis shrimp raptorial appendage strikes were collected
 using high speed video (20,000 frames s<sup>-1</sup>; 25
 strikes, 12 individuals, 1-6 strikes per individual). Kinematics were
 determined by manually tracking the raptorial appendage over the course of
 a strike using MTrackJ plug-in (V1.5.1, Meijering et al., 2012) in ImageJ
 (v2.0.0, Schneider et al, 2012). Strike kinematics (angular and linear
 velocity and acceleration) were compared to a previously compiled dataset
 of adult mantis shrimp strike kinematics (McHenry et al., 2016). The speed
 of the larval mantis shrimp strike was compared to a newly compiled
 dataset collected from the literature of swimming and feeding speeds
 from other larval aquatic organisms.
description: <strong>ReadMe File: "README.pdf"</strong> The ReadMe file steps through the contents for each file and folder contained in this repository. Please review this file first, it includes helpful information on how to connect the R code and data together. <strong>Rcode: "LarvalMantisShrimpKinematicsCode_FINAL.rmd"</strong> This R code includes all of the kinematics code and statistical analyses used in this study. <strong>Larval Mantis Shrimp ID and Metadata: “Larval.ID_forkinematics.csv”</strong> This is the metadata file and general information needed for running the kinematics Rcode. <strong>Larval LaMSA Mechanism: “LarvalLaMSAMechanism.csv”</strong> This spreadsheet contains data used to infer the LaMSA mechanism from a highspeed video (20,000 frames s<sup>-1</sup>) of a larval mantis shrimp strike under a microscope slide. <strong>Comparative Mantis Shrimp Kinematics: “MantisShrimpComparativeKinematics.csv”</strong> This spreadsheet contains data used to compare larval mantis shrimp strike kinematics to various adult mantis shrimp kinematics. <strong>Larval Speed Comparisons: “LarvalSpeedComparisons.csv”</strong> This spreadsheet includes data used to compare larval strike speeds to speeds produced by other small larval aquatic organisms. <strong>Larval Strike Kinematics - "StrikeKinematicsData.zip"</strong> This folder contains data used to calculate the kinematics of the larval mantis shrimp strike. There are two different file types, ‘.csv’ files and ‘.mdf’ files. The ‘.mdf’ files are the output files from the manual tracking of larval mantis shrimp strikes using the MtrackJ plugin in FIJI. <strong>Measuring Error From Tracking - "KinematicErrorData.zip"</strong> This folder contains data used to calculate the measurement error from manual tracking of the larval mantis shrimp strikes.