Wilga, C.D. and P.J. Motta. (2000) Durophagy in sharks: feeding mechanics of the hammerhead shark, Sphyrna tiburo. Journal of Experimental Biology. 203: 2781-2796.

This study investigates the motor pattern and head movements during feeding of a durophagus shark, the bonnethead Sphyrna tiburo, using electromyography and simultaneous high-speed video. Sphyrna tiburo feeds almost exclusively on hard-shelled crabs, with shrimp and fish occasionally taken. Sphyrna tiburo captures crabs by ram feeding, then processes or reduces the prey by crushing it between molariform teeth, and finally transports the prey by suction for swallowing. The prey crushing mechanism is distinct from that of ram or bite capture and suction transport. This crushing mechanism is accomplished by altering the duration of jaw adductor muscle activity and modifying jaw kinematics by the addition of a second jaw closing phase. In crushing events, motor activity of the jaw adductor muscles continues (biting of the prey occurs as the jaws close and after the jaws have closed continuing) throughout a second jaw closing phase, unlike capture and transport events when motor activity (biting) ceases at jaw closure. Sphyrna tiburo is able to take advantage of a resource (hard prey) that is not readily available to most sharks by utilizing a suite of durophagous characteristics: molariform teeth; modified jaw protrusor muscle; altered jaw adductor activity; and modified jaw kinematics. Sphyrna tiburo is a specialist on crab prey as supported by the lack of differences in kinematic or motor patterns when offered prey of differing hardness, and its apparent lack of ability to modulate its behavior when feeding on other prey. Functional patterns are altered and coupled with modifications in dental and jaw morphology to produce diverse crushing behaviors in elasmobranchs.