GERRY, SP*; DEAN, MN; WILGA, CD; University of Rhode Island; University of California, Irvine; University of Rhode Island: Bilateral jaw muscle activity in elasmobranchs

Asynchronous activation of bilateral jaw muscles permits a higher degree of motor control during feeding and food processing. Many previous studies on motor activity in elasmobranchs and bony fishes have implanted electrodes unilaterally. Asynchronous muscle activation while feeding has been demonstrated for two batoid species when feeding on complex prey items. Asynchronous muscle activity would be advantageous during shark head-shaking behavior as they reposition their prey. Yet, we would predict bilateral symmetry during suction feeding. We investigated bilateral muscle activity during feeding on multiple prey items. Electrodes were implanted bilaterally in the dorsal and ventral quadratomandibularis and preorbitalis (jaw adductors), epaxialis (head elevator) and coracomandibularis (mouth opener) to observe timing of muscle activation during prey capture. The dorsal and ventral quadratomandibularis and preorbitalis were bilaterally and synchronously active during suction feeding on small pieces of herring, supporting our hypothesis. Further investigation will determine whether complex prey items, like crabs or whole herring, that require head-shaking for processing, elicit asynchronous activity.