Movements of Cephalic Components during Feeding in Some Requiem Sharks (Carcharhiniformes: Carcharhinidae)

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Abstract
Feeding movements of several carcharhinid sharks (Carcharhinus acronotus, C. limbatus, and Negaprion brevirostris), most of them recently captured, were filmed using submersible motion picture cameras as they were fed "prey" of fresh dead fish or fish pieces. Movements of several head components during feeding were studied. Typically, as food is approached, the entire head is raised while the lower jaw descends. When the prey is properly positioned relative to the shark''s mouth to allow capture, the lower jaw is raised to close the mouth, the entire head descends, and the jaws are protruded. Protrusion shifts both jaws forward, and the upper jaw downward to expose its teeth. Both upper and lower sets of functional teeth are loosely connected to their respective jaw cartilages and although they are moveable by external agents, their movement on the jaws may not be under direct control by the shark. Possible rotational movements of each entire upper jaw half can allow its teeth to be turned from a horizontal to a more vertical position. Slightly different head movement patterns occur depending upon whether the shark is initially grasping prey or regrasping it. Occasionally prey are sucked into the mouth. Comparison is made with recent studies on the great white shark. Implications of some of the observed jaw movements are discussed.