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First published online January 31, 2007
Journal of Experimental Biology 210, 655-667 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02664

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Extremely high-power tongue projection in plethodontid salamanders

Stephen M. Deban^1,*, James C. O'Reilly², Ursula Dicke³ and Johan L. van Leeuwen⁴

¹ Department of Biology, 4202 East Fowler Avenue, SCA 110, University of South Florida, Tampa, FL 33620, USA
² Department of Organismal Biology and Anatomy, University of Chicago, 1027 E. 57th Street, Chicago, IL 60637, USA
³ Brain Research Institute, University of Bremen, 28334 Bremen, Germany
⁴ Experimental Zoology Group, Wageningen Institute of Animal Sciences (WIAS), Wageningen University, Marijkeweg 40, 6709 PG Wageningen, The Netherlands

^* Author for correspondence (e-mail: sdeban{at}cas.usf.edu)

Accepted 22 November 2006

Many plethodontid salamanders project their tongues ballistically at high speed and for relatively great distances. Capturing evasive prey relies on the tongue reaching the target in minimum time, therefore it is expected that power production, or the rate of energy release, is maximized during tongue launch. We examined the dynamics of tongue projection in three genera of plethodontids (Bolitoglossa, Hydromantes and Eurycea), representing three independent evolutionary transitions to ballistic tongue projection, by using a combination of high speed imaging, kinematic and inverse dynamics analyses and electromyographic recordings from the tongue projector muscle. All three taxa require high-power output of the paired tongue projector muscles to produce the observed kinematics. Required power output peaks in Bolitoglossa at values that exceed the greatest maximum instantaneous power output of vertebrate muscle that has been reported by more than an order of magnitude. The high-power requirements are likely produced through the elastic storage and recovery of muscular kinetic energy. Tongue projector muscle activity precedes the departure of the tongue from the mouth by an average of 117 ms in Bolitoglossa, sufficient time to load the collagenous aponeuroses within the projector muscle with potential energy that is subsequently released at a faster rate during tongue launch.

Key words: elastic storage, amphibian, feeding, inverse dynamics, kinematics, muscle