Feeding

Feeding in a water medium among vertebrates can take several forms ranging from detritus feeding (ingestion of decaying organic matter on the substrate) to neuston feeding (ingestion of tiny organisms residing in the surface film). Probably the most common mechanism of obtaining food is suction feeding, whereby the predator creates a current by sucking water into the expanded buccal cavity and out through gills, causing prey to be captured in the mouth. Most fish rely on suction feeding, and this mechanism contributes to the effectiveness of detritivores, neustonivores, and aquatic predators. As a consequence, most fish have relatively weak mouths and low bite strength. There are exceptions, such as sharks, but the general rule is that fish depend on suction more than on biting, a circumstance that works effectively because of the liquid nature of the water medium and the associated friction arising between the medium and objects suspended in it. Aquatic amphibians also use suction feeding, although some species have lingual and jaw prehension, particularly during terrestrial stages. The transition to land dwelling among most reptiles has necessitated a revolution in oral structures and

A. The female American alligator (Alligator mississippiensis) buries her eggs under a pile of vegetation. As the plant material decomposes, the heat produced incubates the eggs while the female stays near the nest to guard against predators; B. Embryo development at day 12 after laying; C. Day 30; D. Day 50; E. Eggs hatch at day 65. (Illustration by Marguette Dongvillo)

A. The female American alligator (Alligator mississippiensis) buries her eggs under a pile of vegetation. As the plant material decomposes, the heat produced incubates the eggs while the female stays near the nest to guard against predators; B. Embryo development at day 12 after laying; C. Day 30; D. Day 50; E. Eggs hatch at day 65. (Illustration by Marguette Dongvillo)

kinematics to cope with the less dense medium of air. Because suction feeding does not work effectively in air, jaw prehension with consequent increases in bite strength has been emphasized in the evolution of most reptiles. Jaw prehension involves increased number and volume of the jaw-suspending muscles and increased surface area of muscle origins. Associated with this development was the appearance of temporal openings in the dermal bone surrounding the brain, because these openings allowed some of the jaw-suspending muscles to escape from the constraints of the dermal-chondral fossae and to attach at origin sites on the lateral and dorsal surfaces of the skull.

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