Frilled Shark

With its elongated, eel-like body and strange appearance, the frilled shark has long been likened to the mythical sea serpent. The head is broad and flattened with a short, rounded snout. The nostrils are vertical slits, separated into incurrent and excurrent openings by a leading flap of skin. The moderately large eyes are horizontally oval and lack nictitating membranes (protective third eyelids). The very long jaws are positioned terminally (at the end of the snout), as opposed to the underslung jaws of most sharks. The corners of the mouth are devoid of furrows or folds. The tooth rows are rather widely spaced, numbering 19–28 in the upper jaw and 21–29 in the lower jaw.The teeth number around 300 in all; each tooth is small, with three slender, needle-like cusps alternating with two cusplets.There are six pairs of long gill slits with a "frilly" appearance created by the extended tips of the gill filaments, giving this shark its name. The first pair of gill slits meet across the throat, forming a "collar"

Seldom observed, the frilled shark may capture prey by bending its body and lunging forward like a snake. The long, extremely flexible jaws enable it to swallow prey whole, while its many rows of small, needle-like teeth make it difficult for the prey to escape. It feeds mainly on cephalopods, leavened by bony fishes and other sharks. This species is aplacental viviparous: the embryosemerge from their egg capsules inside the mother's uterus, where they survive primarily on yolk. The gestation period may be as long as three and a half years, the longest of any vertebrate. Litter sizes vary from two to fifteen, and there is no distinct breeding season. Frilled sharks are occasional bycatch in commercial fisheries, but have little economic value. The International Union for Conservation of Nature has assessed it as Near Threatened, since even incidental catches may deplete its population given its low reproductive rate. This shark, or a supposed giant relative, is a suggested source for reports of sea serpents.