Jason Ramsay and Cheryl Wilga. 2007. Morphology and mechanics of the teeth and jaws of white-spotted bamboo sharks (Chiloscyllium plagiosum). Journal of Morphology. 268: 664-682.

 Abstract

White-spotted bamboo sharks (Chiloscyllium plagiosum) feed on soft prey, fishes and squid, and possess the characteristic clutching type dentition that is well suited for grasping and holding such prey.  They also feed on hard prey (durophagy), such as crabs, repeatedly crushing and breaking them into several pieces prior to swallowing. However, the ability to process hard prey is not typically associated with clutching-type dentitions.  Tooth mechanics during capture and processing of these contrasting prey types (hard and soft bodied), requiring functionally different tooth morphologies, is investigated in C. plagiosum using anatomical dissection and manual manipulation of teeth and associated tissues.  The teeth of C. plagiosum are loosely attached to the jaws, allowing movement in both sagittal and frontal planes.  During prey capture, the spike-like tooth cusps pierce the flesh of soft prey, thereby preventing escape.  Tension generated in the dental ligament during jaw protrusion and adduction may counter the flexible tooth attachment and fix the teeth in an erect position, facilitating the puncture of soft prey.  In contrast, when feeding on prey harder than the teeth can pierce, the teeth passively fold inward (depress) towards the oral cavity such that the broad flat labial faces of the teeth are nearly parallel to the surface of the jaws and are used as a crushing surface.  Movement into the depressed position increases the tooth surface area contacting prey and decreases the total stress applied to the tooth, therefore decreasing the risk of structural failure. This mechanism suggests that flexible tooth attachment may be a functionally beneficial adaptation in C. plagiosum that allows for an increase in dietary breadth and is not merely a by-product of rapid tooth replacement.  The durophagous feeding behavior of C. plagiosum is also reflected in the morphology of the jaws, which are robust relative to non-durophagous sharks.  The presence of a jaw joint position that is offset from the occlusal planes of the upper and lower jaws is similar to that in herbivorous mammals.  The offset joint position allows many teeth to contact prey simultaneously and orients force vectors at contact points between the jaws and prey in a manner that will shear or roll prey between the jaws during a bite; thereby, aiding in processing while reducing forward slip of hard prey from the mouth.