Jaw muscle activation patterns of several Batoids

Fishes may increase the flexibility of their feeding apparatus with a specialized morphology or by altering their behavior during capture or processing. Alternatively, fishes can modulate the timing of jaw muscle activation between the left and right sides of the head. Batoids have a unique cranial morphology including an overall flattened body shape, euhyostylic jaw suspension and typically, a loose symphysis at the jaw midline. These features promote flexibility and mobility of the jaws during feeding. Several batoid species have shown asymmetrical movements of their jaws, enabling them to diversify their feeding habits. Using two asynchrony indices, we investigated pairwise activation of the jaw muscles in four species of batoids in order to compare synchronous versus asynchronous activation patterns during prey capture and processing. The four species we investigated all use synchronous activation when feeding on small or large pieces of squid, in contrast to previous studies. Therefore, we recommend future studies that utilize complex prey in order to attempt to elicit asynchronous behaviors.