MODULATION OF PREY-CAPTURE BEHAVIOR IN THE PLETHODONTID SALAMANDER ENSATINA-ESCHSCHOLTZII

The hypothesis that salamander prey-capture behavior is highly stereot yped was tested in the plethodontid salamander Ensatina eschscholtzii using high-speed videography and kinematic analysis of feedings on two types of prey (waxworms and termites). The results show that E. eschs choltzii is capable of modulating the timing and magnitude of tongue a nd jaw movements in response to prey type, Feedings on waxworms, the l arger prey, were characterized by shorter durations and higher velocit ies of tongue and jaw movements compared with feedings on termites, pa rticularly in the latter portion of the feeding sequence (i,e, after p rey contact), To test the hypothesis that sensory feedback through the tongue pad plays a role in modulating feeding movements in response t o prey type, the ramus lingualis of the glossopharyngeal nerve (crania l nerve IX), which is known to carry sensory information from the tong ue pad in salamanders, was transected bilaterally, This experimental d eafferentation of the tongue pad had no effect on the degree or direct ion of differences in feeding kinematics across prey type. These resul ts refute the glossopharyngeal feedback hypothesis, but are consistent with the hypothesis that E, eschscholtzii responds more vigorously to larger prey by assessing prey size visually.