Feeding mechanism of the atlantic guitarfish rhinobatos lentiginosus: modulation of kinematic and motor activity

The kinematics and muscle activity pattern of the head and jaws during feeding in the Atlantic guitarfish Rhinobatos lentiginosus are described and quantified using high-speed video and electromyography to test hypotheses regarding the conservation and modulation of the feeding mechanism. Prey is captured by the guitarfish using suction. Suction capture, bite manipulation and suction transport behaviors in the guitarfish are similar to one another in the relative sequence of kinematic and motor activity, but can be distinguished from one another by variation in absolute muscle activation time, in the presence or absence of muscle activity and in the duration of muscle activity. A novel compression transport behavior was observed that is strikingly different from the other feeding behaviors and has not been described previously in elasmobranchs. The mechanism of upper jaw protrusion in the guitarfish differs from that described in other elasmobranchs. Muscle function and motor pattern during feeding are similar in the plesiomorphic cranial muscles in the guitarfish and the spiny dogfish probably because of their shared ancestral morphology. Modulation in recruitment of jaw and hyoid depressor muscles among feeding behaviors in the guitarfish may be a consequence of duplication of muscles and decoupling of the jaws and hyoid apparatus in batoids.