Abstract
The teeth of captured specimens, of prepared museum specimens, and of highβspeed videotape images of the white shark, Carcharodon carcharias, were compared with respect to (1) deviation of each tooth from the animal's midline and (2) the crown angle of the functional teeth along the jaw margin. Tooth position was measured either directly using a meter stick apparatus or derived from tracings of the video footage. Tooth positions were not statistically unique in any region of the upper or lower jaw but demonstrated less variability in crown angle within 30Β° of the midline (71.48Β° Β± 10Β°). Videotape analysis of feeding sharks indicated an 8.7Β° increase in crown angle of the centermost teeth during bites where the jaws were closed through an angle of 20β35Β° and a 15.7Β° reduction in this same parameter during jaw adduction through 35Β° or more. Such changes in tooth orientation (relative to the rear of the buccal cavity) are ascribed to flexure of the cartilaginous jaws and cranium by the cranial musculature and possibly also to sliding of the tooth bed over the jaw. Outward rotation of the teeth and jaw rami describes a plucking action during feeding or prey sampling, while larger bites rotate the frontmost teeth inward towards the gullet. Functionally, this may make the teeth more effective at grasping small prey items or gouging chunks from larger prey. However, testing of the load required to remove teeth showed no significant increase in tensile resistance with reduced crown angle. Β© 1995 WileyβLiss, Inc.