CARRENO, C. A.*; NISHIKAWA, K. C.; Northern Arizona University, Flagstaff; Northern Arizona University, Flagstaff: Does Xenopus laevis use suction for prey capture?

Unlike most frogs, pipids are aquatic and capture prey underwater. For these aglossal frogs, the typical anuran mode of lingual prey capture is not possible. Because water is dense and viscous, suction feeding is considered to be the most efficient method of aquatic prey capture. To create suction, buccal cavity pressure drops below ambient pressure through a rapid increase in the volume of the mouth. Suction is predicted to be most effective on small, non-elusive prey that are close to the predator. Most teleost fish are suction feeders, and the pipid Hymenochirus exclusively suction feeds, but it is not known whether other aquatic frogs use suction for prey capture. We examined feeding behavior in Xenopus laevis with high-speed image analysis and simultaneous measurements of buccal cavity pressure. Frogs were fed pieces of earthworm placed ~1 cm from the mouth. Xenopus laevis produced subambient pressure (avg. -2.2 kPa; max. �8.85 kPa) in their buccal cavity during feeding. The magnitude of the negative pressure was greatest during prey capture and decreased subsequently during prey manipulation and transport. This is comparable to subambient pressure seen during feeding in teleost fish. Prey capture in Xenopus laevis was accomplished by suction alone, with forelimb scooping, or a combination of both. It is likely that the use of the forelimbs during feeding may have obscured the importance of suction in aquatic anurans.