綠海龜資料

Green sea turtle

Ecology and Life History

Habitat
Green turtles usually inhabit shallow waters associated with seagrass beds.[7] Seagrass meadows within inshore bays, lagoons and shoals are common locations where Chelonia mydas can often be found. This particular species is known to be very selective about their feeding and mating sites and entire generations will often alternately migrate between the same feeding and nesting areas.[2]

Life History
Unlike most sea turtles, which spend most of their adult lives in the ocean, Pacific green turtles are known to willingly crawl onto secluded beaches during the day to bask in the sun.[5]

Green turtles migrate long distances in-between their chosen feeding sites and the isolated islands from which they were hatched. Mature turtles will often return to the same exact beach from which they hatched from. Individual turtles will usually mate every two to four years.[5] Mating seasons vary between populations, but for C. mydas in the Caribbean, mating season is from June to September.[2]

Green turtles reproduce in the typical way that marine turtles do so. After a lengthy mating ritual in the water, the females haul themselves onto the beach above the high tide line. Upon reaching a suitable nesting site, the gravid female then digs a hole with her hind flippers and deposits a number of eggs in the nest. The number of eggs laid per litter depends on the age of the female and differs from species to species, but C. mydas clutches range between 100 to 200 eggs. After laying eggs, the female then covers the nest with sand and returns to the sea.[5]

After around 45 to 75 days, the eggs hatch. As with other marine turtles, C. mydas eggs hatch during the night and the newly-emerged turtles head directly towards the water's edge. This undoubtedly is the most dangerous time in a turtle's life, as the hatchlings make their way to the water, various predators such as gulls and crabs pick off many turtles. A significant percentage of turtle hatchlings never make it to the ocean. Just like other sea turtles, little is known of the life history of juvenile green sea turtles. It is speculated that they take twenty to fifty years to reach mature size.[2]

Etymology and Taxonomic History
The species was originally described by Linnaeus in 1758 as Testudo mydas.[10] In 1868, Bocourt described a particular species of sea turtle as Chelonia agassizi (and Chelonia agassizii - both were once valid names). [11] This "species" was referred to as the black sea turtle.[12] These two separate species were then united in the same species, Chelonia mydas and were given subspecies status. C. mydas mydas referred to the originally described population while C. mydas agassizi referred to the Pacific population.[13][14] This subdivision was later determined to be invalid and all members of the species were then designated Chelonia mydas.[1]

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.

Some debate exists about whether the Black Sea Turtle (Chelonia agassizi) is actually a separate species (bringing the total to 8), or a 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.

Green sea turtle
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Green sea turtle





Binomial name
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.
Chelonia mydas, more commonly known as the green sea turtle, is a large sea turtle belonging to the family Cheloniidae. It is the only species in the genus Chelonia.[1]





[edit] Anatomy and Morphology

Carapace scalation of C. mydas.The appearance of the green sea turtle is that of a typical sea turtle. C. mydas has a dorso-ventrally flattened body, a beaked head at the end of a short neck, and paddle-like arms well-adapted for swimming.[2] Unlike the closely-related hawksbill turtle, the green sea turtle's snout is very short and its beak is unhooked. The horny sheath of the turtle's upper jaw possesses a slightly-denticulated edge while its lower jaw has stronger, more defined denticulation. The dorsal surface of the turtle's head has a single pair of prefrontal shields. Mature C. mydas front appendages have only a single claw (as opposed to the hawksbill's two), although a second claw is sometimes prominent in young specimens. The carapace of the turtle is known to have various color patterns that change over time. Hatchlings of C. mydas, like those of other marine turtles, have mostly black carapaces and light-colored plastrons. Carapaces of juveniles are dark brown to olive, while those of mature adults are either entirely brown, spotted or marbled with variegated rays. Underneath, the turtle's plastron is hued yellow. C. mydas limbs are dark-colored and lined with yellow, and are usually marked with a large dark brown spot in the center of each appendage.[3]
The green sea turtle is known to grow up to one and a half meters long. While individuals have been caught that reached weights of up to 315 kilograms, average weight of mature individuals is around 200 kilograms. The largest Chelonia mydas ever recorded weighed 395 kilograms (871 lbs.)[4] The species is known to live up to eighty (80) years in the wild.[5]

綠蠵龜檔案

學 名： Chelonia mydas
俗 別 名： 綠海龜、海龜、石龜
英 名： Green sea turtle


The shape characteristic two sides have 4 piece of shields boards, assumes , slightly has the motley pattern, a forehead scale only pair, the foreleg has a pair of fingernail. The back head of a jia amounts to 153 centimeters, because his/her the body fat is the green, therefore calls the green turtle. Minister has the lamella, necking in when can catch, therefore is unable completely to shrink in the shell. Its abdomen assumes the yellow, the young turtle needs the 10~20 year only then to reach the mature stage, Cheng Kueit'i about the long approximately 120~150 centimeter, body weight approximately 120 kilograms. The ecology habit is the swimming master, the large-scale migration sea turtle, can look for food in the fixed region, and spawns in another. Take the seaweed as the staple food, occasionally also eats the mollusk, the arthropod or the fish. Often in is covered with the seaweed the shallow sea area to take in food, the young turtle leaning meat, after grows up becomes omnivorously, is in the sea turtle only takes in food more seaweeds' type, also is only can come ashore exposes to the sun solar the type. The female turtle each 2~3 year spawns a time, each reproduces Ji K'och'an the 3~7 nest egg, each nest 100~150 egg. Each only female turtle needs the ability which the 15~50 year only then has spawns, also must be higher than in 25 degrees centigrade sand beaches in the temperature to be able 夠 to spawn. Roosts distributes mainly in the equator, subtropics coast sand beach temperature and so on mainland coast, islands is higher than 25 degrees centigrade places to spawn. Are most for the present world quantity, also is nearby Taiwan the sea area common sea turtle type, Taiwan's Penghu looks the peaceful islet, has planned establishes the green turtle protectorate.