Green Sea Turtle
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| Chelonia mydas (Linnaeus, 1758) |
- This page redirects from Chelonia, which is the genus name of this turtle, but has also been used for the order Testudines of all turtles and tortoises.
The Green Sea Turtle (Chelonia mydas) is a large sea turtle, the only member of the genus Chelonia (Brongniart, 1800). This turtle grows to 1-1.5 m in length, and can weigh 200 kg, making it the largest of the hard-shelled turtles. Its distribution extends throughout tropical, subtropical and some warmer temperate waters. Females lay their eggs on traditional nesting beaches, and the turtles often bask in the sand to warm their ectothermic bodies, but otherwise this species is entirely marine.
The green sea turtle was so named because of the green color of its body fat. The adult turtle's algae diet is responsible for the color in its tissues.
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[edit] Description
The carapace is feebly unicarinate (having just one keel) in the young (sometimes with slight indication of lateral keels), arched or subtectiform in the adult. The dorsal shields are juxtaposed, the margin is not or indistinctly serrated, formed of 25 shields.
The snout is very short, with unhooked jaws. The horny sheaths of the upper jaw have a feebly denticulated edge and striated inner surface, those of the lower jaw have a strongly denticulated edge. The alveolar surface of the upper jaw has two strong denticulated ridges, the symphysis of lower jaw is short.
The species has one pair of prefrontal shields. Limbs have usually a single claw, the second digit is sometimes provided with a distinct claw in young specimens.
The young are dark brown or olive above, the limbs are margined with yellow. They are yellow beneath, with a large dark brown spot on the hand and foot. The carapace of adults is olive or brown, spotted or marbled with yellowish coloration.[1]
[edit] Black Sea Turtle
Some debate exists about whether the Black Sea Turtle (Chelonia agassizi) is actually a separate species (bringing the total to 8), or subspecies of the Green Sea Turtle. Black Sea Turtles are very similar to Green Sea Turtles, but are somewhat darker and smaller as a group. The habitat of this proposed species lies along the Pacific coast of Central America and northern South America.
[edit] Conservation status
Several population groups of this species exist, and all are in a vulnerable state. The Hawaii and Southern California green sea turtles are designated threatened, and the Florida and Mexico populations are endangered. In the United Kingdom the species is protected by a Biodiversity Action Plan, due to harvesting in excess from human overpopulation and marine pollution. They have long been used as a meat source by many different peoples, reducing their numbers. This species is used in turtle soup. They are also caught for their shells, leathery skin, and fat.
Other threats to the species' survival include habitat destruction on their beaches, being caught as by-catch by fishermen, egg poaching, trash pollution in the oceans, collisions with watercraft, and artificial lighting on nesting beaches, which confuses the hatchlings and lures them toward roads instead of toward the sea where they should go. A disease called fibropapillomatosis is also a problem in some green sea turtle populations.
[edit] Ascension Island
Ascension Island in the mid atlantic hosts the second largest breeding ground for the Green Sea Turtle in the atlantic, after Costa Rica. Each year, between 6,000 and 15,000 nests are laid by the turtle, and the turtles nesting on the island are the largest Green Turtles in the world, being 1.5 metres in length and weighing up to 300kg. The Turtles which breed in Ascension, migrate from Brazil, in what is one of the longest migrations of any creature on earth. The turtles repeat this every 3-4 years. The story of the turtles on Ascension has been a sad one, since the island's discovery in 1502, and up to the turn of the 20th century, turtling was one of the things the island was famous for. Now however, there is an active conservation programme taking place, and there has been an Ascension Island Green Turtle Fund set up to do this. Thankfully, due to low tourist numbers on the Island's long beaches, there are plenty of nesting sites for the turtles there.
[edit] Florida and the Caribbean
Important feeding grounds for the green sea turtle in Florida include Indian River Lagoon, the Florida Keys, Florida Bay, Homosassa, Crystal River and Cedar Key.
The primary nesting sites in U.S. Atlantic waters are along the east coast of Florida, particularly Hutchinson Island, with additional sites in the U.S. Virgin Islands and Puerto Rico. Sites in Suriname and in Tortuguero, Costa Rica are also reported. This western Atlantic population reaches sexual maturity at anywhere from 20-50 years.
Before the inclusion of the turtles in the Endangered Species Act and the Convention on International Trade in Endangered Species, commercial farms such as the Cayman Turtle Farm in the West Indies bred them for commercial sale and held as much as 100,000 turtles at any one time. But when the markets were closed due to the new protections, some went bankrupt and drastically reduced their stock. They currently now operate only as tourist attractions with around 10,000 turtles at any one time. See http://www.turtle.ky/history.htm for further historical information.
[edit] Hawaii
The turtle is found throughout the Hawaiian Islands, all the way to Midway The native Hawaiian word honu is often used. Ninety percent of the Hawaiian population breed and nest at French Frigate Shoals, from April to November. Males apparently make the journey every year, while females make it at two to four year intervals. Sexual maturity comes at about 25 years.
The honu has made a remarkable comeback and is now the subject of eco-tourism and has become something of a state mascot. Students of the Hawaiian Preparatory Academy (a high school) on the Big Island have tagged thousands of specimens over the past two decades.
[edit] Borneo
Conservation efforts have been boosted by eco-tourism in Sabah, Borneo. The island of Pulau Selingaan (also known as 'Turtle Island') is home to a turtle hatchery. Staff on the island collect some of the eggs laid each night and place them in a hatchery to protect them from predators. Incubation is approximately 60 days. Once hatched, tourists are permitted to assist in the release of the baby turtles into the sea.
[edit] Gallery
 Green Sea Turtle - Honu(Chelonia mydas) |
 A Sea Turtle resting on Punalu'u Black Sand Beach (Photo: Lisa Weber) |
 Two Sea Turtles mating underwater in the reefs of Ascension Island.(Photo: Jimmy Young) |
[edit] References
- ^ Boulenger, G. A. (1890) Fauna of British India. Reptilia and Batrachia.
- Seminoff (2004). Chelonia mydas. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 09 May 2006. Database entry includes a lengthy justification of why this species is endangered
- Chelonia mydas (TSN 173833). Integrated Taxonomic Information System. Accessed on 6 February 2006.
- US Fish and Wildlife Service sites:
- Audubon Observes Florida Sea-Turtles The great naturalist James Audubon observes the nesting behavior of Florida Sea-Turtles including the Green Sea-Turtle (1832).
- Daniel Glick, "Back From the Brink", Smithsonian, September, 2005, pp. 54-55.
- Green Sea Turtle Description of the species mentioning black sea turtle debate.
[edit] External link
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