Frilled shark

The frilled shark (Chlamydoselachus anguineus), also known as the lizard shark, is one of the two extant species of shark in the family Chlamydoselachidae (the other is the southern African frilled shark, Chlamydoselachus africana). The frilled shark is considered a living fossil, because of its primitive, anguilliform (eel-like) physical traits, such as a dark-brown color, amphistyly (the articulation of the jaws to the cranium), and a 2.0 m (6.6 ft)–long body, which has dorsal, pelvic, and anal fins located towards the tail. The common name, frilled shark, derives from the fringed appearance of the six pairs of gill slits at the shark's throat. The two species of frilled shark are distributed throughout regions of the Atlantic and the Pacific oceans, usually in the waters of the outer continental shelf and of the upper continental slope, where the sharks usually live near the ocean floor, near biologically productive areas of the ecosystem. To live on a diet of cephalopods, smaller sharks, and bony fish, the frilled shark practices diel vertical migration to feed at night at the surface of the ocean. When hunting food, the frilled shark curls its tail against a rock and moves like an eel, bending and lunging to capture and swallow whole prey with its long and flexible jaws, which are equipped with 300 recurved, needle-like teeth. Reproductively, the two species of frilled shark, C. anguineus and C. africana, are aplacental viviparous animals, born of an egg, without a placenta to the mother shark. Contained within egg capsules, the shark embryos develop in the body of the mother shark; at birth, the infant sharks emerge from their egg capsules in the uterus, where they feed on yolk. Although it has no distinct breeding season, the gestation period of the frilled shark can be up to 3.5 years...