The strike of the tiger salamander: quantitative electromyography and muscle function during prey capture

Abstract

1. We provide a quantitative description of the motor pattern of 11 cranial muscles that control terrestrial prey capture behavior via tongue projection in the tiger salamander (Ambystoma tigrinum) and test the hypothesis that the cranial motor pattern does not differ between successful and unsuccessful strikes. 2. Simultaneous high-speed video images and electromyograms from cranial muscles were recorded during prey capture by 4 individuals. Neither the time to prey contact by the tongue nor gape cycle duration during the strike were significantly different between successful and unsuccessful strikes. In addition, 76 out of 77 parameters measured from 11 cranial muscle electromyograms during the strike showed no significant differences between successful and unsuccessful captures. We conclude that the strike of the tiger salamander shows little variability under these experimental conditions. 3. During the strike all head muscles have nearly synchronous onsets of electromyographical activity. The subarcualis rectus 1 muscle exhibits two bursts of activity: one during tongue projection and a second during tongue retraction. The genioglossus and interhyoideus muscles both show sharp single peaks of activity during the tongue projection phase. The depressor mandibulae muscle typically shows a second peak in activity coincident with the plateau phase of the gape cycle.