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 feed ing in the Atlantic guitarfish Rhinobatos lentiginosus are described and qu antified using high-speed video and electromyography to test hypotheses reg arding the conservation and modulation of the feeding mechanism. Prey is ca ptured by the guitarfish using suction. Suction capture, bite manipulation and suction transport behaviors in the guitarfish are similar to one anothe r in the relative sequence of kinematic and motor activity, but can be dist inguished from one another by variation in absolute muscle activation time, in the presence or absence of muscle activity and in the duration of muscl e activity. A novel compression transport behavior was observed that is str ikingly different from the other feeding behaviors and has not been describ ed previously in elasmobranchs. The mechanism of upper jaw protrusion in th e guitarfish differs from that described in other elasmobranchs. Muscle fun ction and motor pattern during feeding are similar in the plesiomorphic cra nial muscles in the guitarfish and the spiny dogfish probably because of th eir shared ancestral morphology. Modulation in recruitment of jaw and hyoid depressor muscles among feeding behaviors in the guitarfish may be a conse quence of duplication of muscles and decoupling of the jaws and hyoid appar atus in batoids.