| In this study, feeding behavior was examined in four species of pipids, Pipa pipa, Xenopus laevis, Hymenochirus curtipes, and Pseudhymenochirus merlini, representing four of the five genera of the Pipidae. First, direct measurements of buccal cavity pressure during prey capture recorded localized pressure changes. For each species, the internal buccal pressure was found to drop significantly below ambient pressure, and high-speed digital imaging revealed that each change in pressure corresponded to each gape cycle. Prey items often moved toward the frog's mouth from beyond the tip of the jaws and continued to travel into the mouth without contacting the frog's forelimbs. Each species of pipid was found to use suction to some extent. Pipa pipa and X. laevis employed forelimb scooping in addition to suction feeding, but H. curtipes and P. merlini used suction feeding exclusively.; The kinematics of suction feeding were analyzed within the pipid frogs, and compared to other suction feeding vertebrates (lungfish, teleost fish, turtles, and salamanders) as well as terrestrial feeding anurans. Pipid frogs were kinematically similar to one another in a principal components analysis, with H. curtipes and P. merlini loosely clustered. Each species exhibited a wave of buccal expansion during suction feeding, similar to that observed in teleosts and other aquatic vertebrates. The feeding behavior of pipid frogs appears to be functionally convergent with other suction-feeding vertebrates, and not phylogenetically constrained.; The morphology of the feeding apparatus in pipid frogs is modified from that of a typical anuran and shares characteristics with other suction-feeding vertebrates. Using buccal molds, the buccal cavity was found to be greatly enlarged, 4-8 times the size found in other anurans. Measurement from cleared and stained specimens showed that the hyoids of pipids are expanded in overall area, and shifted posteriorly to support the expanded buccal cavity. The associated feeding musculature is modified to produce expansion of the buccal cavity by retraction and depression of the hyoid. |
