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sea turtle

sea turtle, name for several species of large marine turtles found in tropical and subtropical oceans. These turtles are modified for life in the ocean by having flipperlike forelimbs without toes and lightweight shells. Their heads are too large to be withdrawn into the shell. They spend most of their lives in the water, but come ashore to lay their eggs. Nearly all species have a circumglobal distribution although there are differences between the Atlantic and the Pacific populations. Most sea turtles are found in North American waters as far N as the U.S. S Atlantic coast and Baja California.

All sea turtle species are declining in numbers, owing in large part to the destruction of the eggs, which are widely used as food in tropical regions. Sea turtle meat is also eaten, and there is a market for turtle oil, hide, and shell. In a few places, such as Sarawak, harvesting of eggs is regulated by law to insure propagation of the species. The size of sea turtles has also decreased, owing to the hunting of large specimens.

The green turtle, Chelonia mydas, with greenish to brownish skin and shell, formerly reached weights of 1,000 lb (450 kg); the largest now found are about 4 ft (120 cm) long and weigh about 500 lb (225 kg). The green turtle feeds chiefly on marine vegetation and is most abundant in shallow water. The loggerhead, Caretta caretta, is a large-headed brown to reddish turtle. Chiefly carnivorous, it ranges from open oceans to coastal salt marshes and stream mouths. Like the green turtle it sometimes comes ashore in uninhabited places to bask.

The hawksbill, or tortoiseshell turtle, Eretmochelys imbricata, may reach 30 in. (75 cm) in length and weigh 100 lbs (45 kg). The horny plates of its shell are translucent and have a variegated color pattern, chiefly brown and yellow. These plates have long been valued for the making of ornamental objects. Although tortoiseshell has to a large extent been replaced in many applications by plastic, a renewed demand for the genuine material poses a serious threat to the hawksbill.

The ridleys, the smallest sea turtles, inhabit shallow offshore waters. The 2-ft (60-cm) long, gray Kemp's, or Atlantic, ridley, Lepidochelys kempii, breeds only in the Gulf of Mexico, although the young are often carried by the Gulf Stream to the Carribean Sea and Europe. The slightly larger, greenish olive, or Pacific, ridley (L. olivacea), also known as the oliveback, is found in the Indian and Pacific oceans. The leatherback is the largest of all turtles; it belongs to a separate family from the other sea turtles.

All sea turtles other than the leatherback are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Chelonia, family Chelonidae; the leatherback belongs to the family Dermochelidae.


See J. R. Spotila, Saving Sea Turtles (2011).

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1. a large-headed turtle, Caretta caretta, occurring in most seas: family Chelonidae
2. loggerhead shrike a North American shrike, Lanius ludovicianus, having a grey head and body, black-and-white wings and tail, and black facial stripe
3. a tool consisting of a large metal sphere attached to a long handle, used for warming liquids, melting tar, etc.
4. a strong round upright post in a whaleboat for belaying the line of a harpoon
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
HH Sayyida Tania Al Said ESO's President, said, "Despite being an integral part of our global ecosystem for millennia, today loggerhead turtles face a substantial threat due to unsustainable fishing practices, marine pollution, climate change, and development on nesting beaches.
Harris said if the crew are flying there but don't have a full plane, they are willing to take some of the large loggerhead turtles.
Ditto David Attenborough, who has provided all the second-hand experiences of wildlife encounters we could ever want without the need to get up close and personal with a loggerhead turtle in the Mediterranean.
Two methods were used to estimate the sex ratio of hatched loggerhead turtles. The first used the mean temperature during the middle third of the incubation period, while the second used the incubation duration.
A significant portion of the world's population of loggerhead turtles, up to 80% of the North Atlantic population, nests on peninsular Florida's beaches and produce ~90% of all hatchlings in the western North Atlantic Ocean (TEWG, 2009).
The campaign was part of the fourth annual Masirah Festival for Loggerhead Turtles and included a host of fun-filled activities such as beach clean ups and football games funded by BP Oman.
Near capital Argostoli is Koutavos Lagoon, a feeding ground for loggerhead turtles. At Lixouri are the Swallow Holes of Katovothres, where sea water disappears underground to a lake, and which once powered a water mill.
Lara Bay offers loggerhead turtles, which lay their eggs here between June and September.
Six rehabilitated sea turtles (two Green Sea Turtles, two Loggerhead Turtles and two Hawksbill Turtles) will each be tagged with a satellite device that monitors their whereabouts in the earth's oceans.
Loggerhead turtles nest at the Coast of Quintana Roo from May to October, during which females lay around 120 eggs per nest.