Feeding structures of the white shark, Carcharodon Carcharias (Linnaeus), with notes on other species

Fresh and prepared museum specimens of the white shark Carcharodon carcharias, bull shark Carcharhinus leucas, and salmon shark Lamna ditropis were measured and compared with respect to tooth position and anterior buccal cavity dimensions. Coordinates of functional tooth position were defined by 1) deviation from the midline and 2) degree of erection. Tooth positions were not unique in any region of the mouth/ but demonstrated less variablity within 30° of the midline, particularly for male specimens of all three species (71.48° +- 10° erect) and all Carcharhinus leucas specimens (46.58° +-.96° erect). Analysis of high-speed videotape of white shark feeding indicated a 15.7° reduction in tooth cutting angle with jaw adduction following upper jaw protraction. It is suggested that such changes in tooth cutting angles during feeding are principally the result of jaw flexure, and may make the teeth more effective by angling them inward towards the gullet. Values for tooth removal from fresh-frozen white shark material using a tensile testing apparatus ranged from 12 kg (for a 110° erect tooth) to 70 kg (for a 59° erect tooth). Removal load was applied directly outward from the mouth to simulate a resistant prey item, and was not significantly different for degree of erection or tooth position on the jaw margin. Tooth position is seen to change with jaw protraction, however this change does not enhance tooth functionality by increasing the load required to remove the tooth.Science, Faculty ofZoology, Department ofGraduat