A spiral valve, which increases surface area and slows food movement, is present in the intestine. Electric sensory regions that detect muscle contractions of prey are located on the head. A lateral line system is present along the flanks. It is composed of rows of microscopic organs sensitive to water pressure changes and detects vibrations. A pair of auditory organs also detect sound waves passing through the water.
Sharks reproduce sexually with internal fertilization.
A pair of claspers on the pelvic fins of males transfers sperm into the female reproductive tract. Some species are oviparous , some are ovoviviparous , and a few are viviparous . Rays are adapted to a bottom-dwelling life style. They have dorsoventrally flattened bodies. Their jaws are used to crush mollusks and crustaceans.