Motta, P.J. and C.D. Wilga (2001). Advances in the study of feeding behaviors, mechanisms, and mechanics of sharks. In Biology and sensory biology of sharks: past, present and future studies (S. Gruber and T. Tricas, eds). Developments in the Environmental Biology of Fishes. 20: In Press. From the symposium The Behavior and Sensory Biology of Sharks and Rays: State of the Art and Future Direction. A Symposium in Honor of Donald R. Nelson presented at the Annual Meeting of the American Elasmobranch Society, July 1998, University of Guelph, Ontario, Canada.

Sharks represent an ancient group of highly successful predatory fishes. More studies on their diets, feeding behaviors, feeding mechanisms, and mechanics are needed yet lacking in some cases. Dietary studies of sharks are generally more abundant than those on feeding activity patterns, and most of the studies are confined to relatively few species, many being carcharhiniform sharks. Dietary studies reveal that sharks are generally asynchronous opportunistic feeders on the most abundant prey item, which is primarily other fishes. Studies of natural feeding behavior are not plentiful and often confined to a few select species, and many observations of feeding behavior are based on anecdotal reports. To capture their prey sharks either ram, suction, bite, filter, or use these in combination. Foraging may be solitary or aggregate, and while cooperative foraging has been hypothesized it has not been conclusively demonstrated. Studies on the anatomy of the feeding mechanism are abundant and thorough, and far exceed the number of functional studies. Many of these studies have attempted to determine the functional role of morphological features such as the protrusible upper jaw, but only relatively recently have we begun to interpret the mechanics of the feeding apparatus and how it relates to feeding behavior. Because teeth are so well preserved in the fossil record and easily studied in extant sharks, much is known about their anatomy but again functional studies are primarily theoretical and await experimental analysis. Recent mechanistic approaches to the study of prey capture have revealed that although many species have conservative kinematic and motor patterns, the ability to modulate feeding behavior varies. The relationship of jaw suspension to feeding is not as clear as was believed, and contrary to previous interpretations upper jaw protrusibility appears to be more related to the morphology of the upper jaw-chondrocranium articulation, and not the type of jaw suspension which has traditionally considered the articulation between the hyomandibula and chondrocranium. Finally, we propose a set of specific hypotheses including: 1) functional specialization for suction feeding which states that morphological and functional specialization for suction feeding has repeatedly arisen in numerous elasmobranch lineages, 2) functional convergence in aquatic suction feeding which proposes that similar hydrodynamic constraints in bony fishes and sharks result in convergent morphological and functional specializations for suction feeding in both groups, 3) modulatory feeding which states that suction capture events in sharks are more stereotyped and therefore less modulated compared to ram and bite capture events, and 4) uncoupling of jaw suspension and feeding behavior whereby the traditional categorization of jaw suspension types in sharks is not a good predictor of jaw mobility and prey capture behavior. Together with a set of questions these hypotheses help to guide future research on the feeding biology of sharks.