MARTINEZ, C.*; CARRENO, C. A.; NISHIKAWA, K. C.; Dine College, Shiprock, NM; Northern Arizona University; Northern Arizona University: The effect of prey size on feeding behavior in Xenopus laevis

Frogs in the family Pipidae are fully aquatic and capture prey underwater. For these aglossal frogs, the typical anuran mode of lingual prey capture is not possible. The pipid Xenopus laevis uses its forelimbs to grasp or scoop prey items into its mouth, but it also produces suction while feeding. We examined the frequency of different feeding behaviors as a function of prey size. We hypothesized that forelimb scooping would be used to capture large prey and only small prey would be captured using inertial suction. Xenopus laevis were fed whole bloodworms, or �, �, or whole earthworms. These prey are non-elusive and represent a wide range of sizes. Prey items were presented in random order ~1-2 cm in front of the frog. Feeding behavior was digitally imaged from a dorsal view. Feeding was scored as forelimb scooping if the prey was contacted by the forelimb, compensatory suction if the frog lunged forward but the prey did not move away, and inertial suction if the prey item moved toward the frog and was not contacted by the forelimbs. Forelimb scooping was found to be the most common method of prey capture, occurring about 75% of the time. Large prey items were most frequently captured by forelimb scooping. Compensatory suction was used to capture a wide size range of prey. Inertial suction was used infrequently and only to capture small prey. These data suggest that Xenopus laevis modulates its feeding behavior in response to prey size.