The biology of one of the oldest and most successful predators, sharks, has often intrigued scientists and amateurs. Sharks and their relatives, the skates and rays, originated from bony fish ancestors some 400 million years ago. Today they are the dominant predators of the oceans. Despite great interest in their feeding behaviors, there exists scant scientific knowledge of their feeding mechanisms. The anatomy of the heads and jaws of arguably the most successful group, the requiem or carcharhiniform sharks (tiger, lemon, hammerhead sharks), has been little studied. Dr. Philip Motta of the University of South Florida, with assistance from colleagues at the Mote Marine Laboratory and the Florida Institute of Technology, is studying the feeding mechanics and cranial anatomy of two groups of sharks with contrasting modes of feeding. These are biting and gouging lemon sharks, and suction and crushing nurse sharks. Descriptive study of jaw musculature and cranial nerves will be supplemented with high-speed photography of feeding behaviors and electromyography, to measure electrical signals controlling feeding movements. Detailed examination of the functional morphology of sharks will help in understanding the evolution of contrasting feeding styles in these marine predators, and in general will improve understanding of the origins of feeding behaviors in early vertebrate groups.
