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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. Deban1,*, 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


Figure 1
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  		Fig. 1. (A) Kinematic profiles from a representative feeding in Hydromantes genei showing required instantaneous muscle-mass-specific power versus time in the upper trace, and instantaneous acceleration, velocity and smoothed and interpolated position versus time in the lower traces. Open circles in the position trace indicate raw position data, and the filled circles correspond to the video frames shown in B. (B) Image sequence of the same feeding from which the kinematics in A were derived. Scale bar, 1 cm; times (ms) are from the start of tongue projection. Note the long tongue reach and the peak required power output of over 3000 W kg–1.

 

Figure 2
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  		Fig. 2. (A) Kinematic profiles from a representative feeding of extremely high power in Bolitoglossa dofleini showing required instantaneous muscle-mass-specific power versus time in the upper trace, and instantaneous acceleration, velocity, and smoothed and interpolated position versus time in the lower traces. Open circles in the position trace indicate raw position data, which correspond exactly to the video frames shown in B. (B) Images of the same feeding. Note the extremely high-power values, and that peak power is achieved early in tongue projection. Times (ms) are from the start of tongue projection.

 

Figure 3
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  		Fig. 3. (A) Kinematic profiles from a representative feeding in Eurycea guttolineata showing required instantaneous muscle-mass-specific power versus time in the upper trace, and instantaneous acceleration, velocity, and smoothed and interpolated position versus time in the lower traces. Open circles in the position trace indicate raw position data, which correspond exactly to the video frames shown in B. (B) Image sequence of the same feeding. Scale bar, 5 mm; times (ms) are from the start of tongue projection.

 

Figure 4
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  		Fig. 4. Frequency histograms of all feedings from Hydromantes, Eurycea and Bolitoglossa, showing number of feedings analyzed with different levels of required muscle-mass-specific power. In all taxa, most feedings are over 1000 W kg–1, and extremely high power was observed repeatedly, but less frequently.

 

Figure 5
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  		Fig. 5. Electromyographs from the subarcualis rectus muscle in four feedings of one individual of Bolitoglossa dofleini. Traces are aligned at the time that the tongue first appears at the mouth, marked by the vertical broken line. Note that EMG activity has nearly ceased by this time and that considerable modulation occurs in the duration and timing of the EMG burst.

 

Figure 6
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  		Fig. 6. Scatterplots from 25 feedings in three individuals of Bolitoglossa dofleini showing least-squares regression lines and coefficients of determination (r2) of variables that showed a significant effect of SAR activation–projection delay in the ANCOVA (see text), plotted here against SAR activation–projection delay: (A) maximum tongue reach, (B) specific work, (C) maximum velocity, (D) time of maximum velocity and (E) time of maximum power.

 

Figure 7
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  		Fig. 7. Scatterplots from 25 feedings in three individuals of Bolitoglossa dofleini showing least-squares regression lines and coefficients of determination (r2) of variables that showed a significant effect of SAR EMG area in the ANCOVA, plotted against SAR EMG area: (A) maximum tongue reach, (B) specific work and (C) maximum velocity.

 

Figure 8
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  		Fig. 8. (A) Confocal laser microscope image of a cross section of the tongue projector muscle (m. subarcualis rectus) of Hydromantes genei. The epibranchial cartilage is in the center, surrounded by short (~1 mm) muscle fibers with a variety of orientations. (B) The same image with the position of the collagenous aponeuroses marked as black lines. All muscle fibers originate and insert on these aponeuroses. The section is approximately 2 mm in its widest diameter.

 




© The Company of Biologists Ltd 2007