Comparative feeding kinematics of temperate pond-dwelling tadpoles (Anura, Amphibia)
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Several studies have explored various components of feeding kinematics in anuran larvae; however, a direct comparison of feeding kinematics among morphologically similar and sympatric taxa has not been undertaken. We used high-speed videography (500 frames/s) to capture feeding kinematics of Anaxyrus fowleri (Hinckley, 1882) (Fowler’s Toad), Hyla chrysoscelis (Cope, 1880) (Grey Treefrog), Scaphiopus holbrookii (Harlan, 1835) (Eastern Spadefoot Toad), and Lithobates sphenocephalus (Cope, 1889) (Southern Leopard Frog) tadpoles as they foraged from an algal-covered substrate. In total, we filmed 120 feeding sequences from 25 feeding bouts and quantified eight kinematic variables that were common among all four species. Despite relatively similar keratinized feeding structures among taxa, our videography data revealed fundamental differences in how the tadpoles used these structures. One specific difference was in the speed of the gape cycle. Among taxa, S. holbrookii tadpoles had the longest gape cycle and longest time to reach maximum gape, whereas A. fowleri and L. sphenocephalus tadpoles had shorter durations for both variables and did not differ between species. We also found species differences in the magnitude that tadpoles narrow their lower jaw sheath. Irrespective of gape size, the lower jaw sheath of S. holbrookii tadpoles narrowed by approximately 26% of its maximum width—a twofold difference from A. fowleri tadpoles, which narrowed only 13%. Our study revealed that tadpoles with similar oral structures feeding on the same substrate can exhibit major differences in feeding kinematics.
KeywordsBiomechanics Anaxyrus Hyla Lithobates Scaphiopus Keratin Labial teeth Jaw sheath
We thank Ron Altig for providing comments during the planning stages of this experiment. Angela Horner and Don Miles provided statistical advice. Collection permits from Tennessee were obtained prior to collecting the animals used in these experiments, and all experimental procedures were approved by the University of Memphis IACUC. This publication was developed, in part, under a GRO Research Assistance Agreement No. MA-916980 awarded by the U.S. Environmental Protection Agency to MDV. It has not been formally reviewed by the EPA. The views expressed in this document are solely those of the authors, and the EPA does not endorse any products or commercial services mentioned in this publication. RJW’s participation was supported by the Natural Science and Engineering Research Council of Canada.
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