SEA TURTLE

any of the marine turtles of the families Dermochelyidae (leatherback turtle) and Cheloniidae (green turtle, loggerhead, hawksbill, and ridley). Sea turtles, in adaptation to an aquatic life, have limbs modified into flippers for efficient swimming. They generally leave the water only during the breeding season, when the female emerges to dig a nest on land and deposit her eggs. The leatherback turtle (Dermochelys coriacea), largest of living turtles, may attain a total length of about 2.1 metres (7 feet) with a weight of about 540 kilograms (1,200 pounds) and a span of about 2.7 m from the tip of one front flipper to the tip of the other. Maximum reported lengths and weights range up to 3 m and about 900 kg but are poorly authenticated. The leatherback has no visible shell. A shell is present but consists of bones buried in the dark brown or blackish skin. There are seven pronounced longitudinal ridges on the back of the turtle and five on the underside. The leatherback is a strong swimmer and inhabits open seas throughout the world. It apparently is omnivorous and takes both animal and plant material. The green turtle (Chelonia mydas) is named for the greenish colour of its fat. It is a large, heavy reptile, usually about 0.71.0 m in shell length and about 90140 kg in weight. The maximum length and weight are about 1.2 m and 375 kg. The upper shell of the green turtle is wide and smooth, and the overall colouring of the animal is brown or slightly greenish. The green turtle is found in warm, coastal waters around the world. It feeds mainly on marine grasses and, unlike other sea turtles, sometimes emerges onto land to bask in the sun. The loggerhead (Caretta caretta) is a large turtle similar to the green turtle but with a relatively larger head. It is reddish brown or brown in colour. The loggerhead attains a shell length of about 0.72.1 m. A large specimen usually weighs about 135 kg, but weights of almost 400 kg have been recorded. The loggerhead, found in oceans throughout the world, is a carnivorous reptile with a reportedly bad disposition. The hawksbill (Eretmochelys imbricata) is a relatively small sea turtle that takes its common name from the shape of its hooked jaws and its species name (imbricata) from the overlapping plates on its upper shell. The hawksbill is found in warm waters throughout the world and is an aggressive reptile that feeds on both plant and animal material. It usually attains a shell length of about 4055 cm (1622 in.) and a weight of about 1345 kg (29100 lb). The ridleys (Lepidochelys) are small sea turtles with wide, rounded shells. The Atlantic ridley (L. kempii) is a gray turtle with a shell about 6079 cm long. It is found in the Gulf of Mexico and occasionally strays, in the Gulf Stream, north to New England and east to Great Britain and Europe. The Atlantic ridley is widely known as the bastard turtle, the name stemming from the mistaken belief that it is the offspring of a green turtle and a loggerhead. The Pacific ridley (L. olivacea) inhabits warm waters of the Indo-Pacific region. It is distinguished from the Atlantic form by its greenish colour and larger size. It feeds on both animal and vegetable material.