@article{810f8a856c37406b8db76e8d17a8451e,
title = "Snap-jaw morphology is specialized for high-speed power amplification in the Dracula ant, Mystrium camillae",
abstract = "What is the limit of animal speed and what mechanisms produce the fastest movements? More than natural history trivia, the answer provides key insight into the form-function relationship of musculoskeletal movement and can determine the outcome of predator-prey interactions. The fastest known animal movements belong to arthropods, including trap-jaw ants, mantis shrimp and froghoppers, that have incorporated latches and springs into their appendage systems to overcome the limits of muscle power. In contrast to these examples of power amplification, where separate structures act as latch and spring to accelerate an appendage, some animals use a 'snap-jaw' mechanism that incorporates the latch and spring on the accelerating appendage itself. We examined the kinematics and functional morphology of the Dracula ant, Mystrium camillae, who use a snap-jaw mechanism to quickly slide their mandibles across each other similar to a finger snap. Kinematic analysis of high-speed video revealed that snap-jaw ant mandibles complete their strike in as little as 23 μsec and reach peak velocities of 90 m s-1, making them the fastest known animal appendage. Finite-element analysis demonstrated that snap-jaw mandibles were less stiff than biting non-power-amplified mandibles, consistent with their use as a flexible spring. These results extend our understanding of animal speed and demonstrate how small changes in morphology can result in dramatic differences in performance.",
keywords = "Ants, Finite-element analysis, Functional morphology, MicroCT, Power amplification",
author = "Larabee, {Fredrick J.} and Smith, {Adrian A.} and Suarez, {Andrew V.}",
note = "Funding Information: This work was supported by the National Science Foundation (DDIG DEB-1407279 to F.J.L., IOS-1755336 to A.V.S.), the Smithsonian Institution (Peter Buck Fellowship to F.J.L.), and the National Geographic Society (Explorer's Grant 9481-14 to A.V.S.). Funding Information: Mystrium camillae were granted to A.V.S. by USDA-APHIS (permit P526-16-0281). Permission to collect Stigmatomma pallipes were not required at the time of study. Data accessibility. Morphological data (microCT image stacks and surface volumes) are available through MorphoSource (morphosource.org, project ID: P539). x-y coordinate data of strikes, derived kinematic characteristics, and R scripts for statistical analyses are available from Dryad Digital Repository at http://dx.doi.org/10.5061/dryad.4863215 [43]. Authors{\textquoteright} contributions. F.J.L. designed the study, collected the kinematic and morphological data, performed the data analysis and drafted the manuscript; A.A.S. collected the kinematic data, helped design the study and helped draft the manuscript; A.V.S. conceived of the study, helped design the study and helped draft the manuscript. All authors gave final approval for publication. Competing interests. We declare we have no competing interests. Funding. This work was supported by the National Science Foundation (DDIG DEB-1407279 to F.J.L., IOS-1755336 to A.V.S.), the Smithsonian Institution (Peter Buck Fellowship to F.J.L.), and the National Geographic Society (Explorer{\textquoteright}s Grant 9481-14 to A.V.S.). Acknowledgements. The authors wish to thank B. L. Fisher for organizing the 2014 Ant Course where the Mystrium camillae colony was found, and for helping with collection and export permits. J. C. Gibson and J. Harrison assisted with the microCT of Stigmatomma pallipes. We are also grateful to Sheila Patek for providing access to her laboratory so we could film Mystrium camillae strikes. The authors are also grateful to H. M. Wood and two anonymous reviewers for the constructive comments on early versions of this manuscript. Publisher Copyright: {\textcopyright} 2018 The Author(s) Published by the Royal Society.",
year = "2018",
month = dec,
day = "1",
doi = "10.1098/rsos.181447",
language = "English (US)",
volume = "5",
journal = "Royal Society Open Science",
issn = "2054-5703",
publisher = "The Royal Society",
number = "12",
}