Meeting Abstract

S9-1.5  Jan. 6  Evolution of feeding mechanics in amphibians DEBAN, S.M.; Univ. South Florida, Tampa sdeban@cas.usf.edu

The three major groups of living amphibians have diversified in feeding biomechanics, in both larval and adult phases of their life history. Caecilian larvae have morphology that is consistent with suction feeding, while juveniles of viviparous and direct developing species and adults have been observed to use only jaw prehension in both terrestrial and aquatic situations. Caecilians have evolved a unique biting mechanism concomitant with a burrowing lifestyle. Among anurans, most tadpoles are suspension feeding planktivores, but some have independently evolved a predatory, suction feeding lifestyle. Adult frogs have diversified in terrestrial prey capture mechanisms by elaborating tongue projection along two biomechanical pathways, relying on inertial or hydrostatic elongation of the tongue, which is entirely soft tissue, but many species retain short tongues and pronounced lunging. Suction feeding is known to have evolved once in aquatic adult frogs, but many aquatic taxa use jaw prehension. Salamander larvae are universally predatory suction feeders, but some taxa lack a free-living larval stage. Aquatic adults suction feed using retained larval morphology or novel adult morphology, or use jaw prehension when biomechanically incapable of suction feeding. Terrestrial salamanders have evolved elaborate tongue projection along three biomechanical pathways, or retain short tongue pads and emphasize jaw movements in feeding. Salamanders are unusual in that feeding mechanics are strongly influenced by life history; sharing of features across metamorphosis via heterochrony appears to be more prevalent than in caecilians and anurans, perhaps because movements of the hyobranchial apparatus are critical to both salamander tongue protraction and suction feeding, and and not in jaw prehension and anuran tongue projection.