Description: Its appearance is that of a typical sea turtle. C. mydas has a dorsoventrally flattened body, a beaked head at the end of a short neck, and paddle-like arms well adapted for swimming. Adult green turtles grow to 5 feet long. The average weight of mature individuals is 150 to 419 lbs. and the average carapace length is 31 to 44 inches. Exceptional specimens can weigh 694 lbs. or even more, with the largest known C. mydas having weighed 871 lbs. and measured 60 inches in carapace length.
natomically, a few characteristics distinguish the green sea turtle from the other members of its family. Unlike its close relative the hawksbill sea turtle, the green sea turtle's snout is very short and its beak is unhooked. The neck cannot be pulled into the shell. The sheath of the turtle's upper jaw possesses a denticulated edge, while its lower jaw has stronger, serrated, more defined denticulation. The dorsal surface of the turtle's head has a single pair of prefrontal scales. Its carapace is composed of five central scutes flanked by four pairs of lateral scutes. Underneath, the green sea turtle has four pairs of inframarginal scutes covering the area between the turtle's plastron and its shell. Mature C. mydas front appendages have only a single claw (as opposed to the hawksbill two), although a second claw is sometimes prominent in young specimens.
The carapace of the turtle has various color patterns that change over time. Hatchlings of Chelonia mydas, like those of other marine turtles, have mostly black carapaces and light-colored plastrons. Carapaces of juveniles turn 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
Habitat: Green sea turtles move across three habitat types, depending on their life stage. They lay eggs on beaches. Mature turtles spend most of their time in shallow, coastal waters with lush seagrass beds. Adults frequent inshore bays, lagoons, and shoals with lush seagrass meadows. Entire generations often migrate between one pair of feeding and nesting areas. Green sea turtles, Chelonia mydas, are classified as an aquatic species and are distributed around the globe in warm tropical to subtropical waters. The environmental parameter that limits the distribution of the turtles is ocean temperatures below 44.t to 50 ℉. Within their geographical range, the green sea turtles generally stay near continental and island coastlines. Near the coastlines, the green sea turtles live within shallow bays and protected shores. In these protected shores and bays, the green sea turtle habitats include coral reefs, salt marshes, and nearshore seagrass beds. The coral reefs provide red, brown, and green algae for their diet and give protection from predators and rough storms within the ocean. The salt marshes and seagrass beds contain seaweed and grass vegetation, allowing ample habitat for the sea turtles.
Turtles spend most of their first five years in convergence zones within the bare open ocean that surround them. These young turtles are rarely seen as they swim in deep, pelagic waters. Green sea turtles typically swim at 1.6 to 1.9 mph.
Range: The range of the green sea turtle extends throughout tropical and subtropical oceans worldwide. In the United States Atlantic coast, green sea turtles can be found from Texas and north to Massachusetts. In the United States Pacific coast, they have been found from southern California north to the southernmost tip of Alaska. The largest populations of green sea turtles within the United States coastline are in the Hawaiian Islands and Florida. Globally, the largest populations of sea turtles are in the Great Barrier Reef in Australia, and the Caribbean Sea.
Diet: The diet of green turtles changes with age. Juveniles are carnivorous, but as they mature they become omnivorous. Young sea turtles eat fish eggs, molluscs, jellyfish, small invertebrates, worms, sponges, algae, and crustaceans. Green sea turtles have a relatively slow growth rate because of the low nutritional value of their diet. Body fat turns green because of the consumed vegetation. This diet shift has an effect on the green turtle's skull morphology. Their serrated jaw helps them chew algae and sea grasses. Most adult sea turtles are strictly herbivorous.
Reproduction: Green sea turtles migrate long distances between feeding sites and nesting sites; some swim more than 1,600 miles to reach their spawning grounds. Beaches in Southeast Asia, India, islands in the western Pacific, and Central America are where green sea turtles breed. Mature turtles often return to the exact beach from which they hatched. Females usually mate every two to four years. Males, on the other hand, visit the breeding areas every year, attempting to mate. Mating seasons vary between populations. For most C. mydas in the Caribbean, mating season is from June to September. The French Guiana nesting subpopulation nests from March to June. In the tropics, green turtles nest throughout the year, although some subpopulations prefer particular times of the year. In Pakistan, Indian Ocean turtles nest year-round, but prefer the months of July to December.
Sea turtles return to the beaches on which they were born to lay their own eggs. The reason for returning to native beaches may be that it guarantees the turtles an environment that has the necessary components for their nesting to be successful. These include a sandy beach, easy access for the hatchlings to get to the ocean, the right incubation temperatures, and low probability of predators that may feed on their eggs. Over time these turtles have evolved these tendencies to return to an area that has provided reproductive success for many generations. Their ability to return to their birthplace is known as natal homing. The males also return to their birthplaces in order to mate. These males that return to their homes know they will be able to find mates because the females born there also return to breed. By doing this, the green sea turtles are able to improve their reproductive success and is why they are willing to expend the energy to travel thousands of miles across the ocean in order to reproduce.
Mating behaviour is similar to other marine turtles. Female turtles control the process. A few populations practice polyandry, although this does not seem to benefit hatchlings. After mating in the water, the female moves above the beach's high tide line, where she digs a hole 11 to 22 inches in depth with her hind flippers and deposits her eggs. The hole is then covered up again. Clutch size ranges between 85 and 200, depending on the age of the female. This process takes about an hour to an hour and a half. After the nest is completely covered, she returns to the sea. The female will do this 3 to 5 times in one season.
The eggs are round and white, and about 1.75 inches in diameter. The hatchlings remain buried for days until they all emerge together at night. The temperature of the nest determines the sex of the turtles at around the 20 to 40 day mark. At around 50 to 70 days, the eggs hatch during the night, and the hatchlings instinctively head directly into the water. This is the most dangerous time in a turtle's life. As they walk, predators, such as gulls and crabs, feed on them. A significant percentage never make it to the ocean. Little is known of the initial life history of newly hatched sea turtles. Juveniles spend three to five years in the open ocean before they settle as still immature juveniles into their permanent shallow-water lifestyle. It is speculated that they take twenty to fifty years to reach sexual maturity. Individuals live up to eighty years in the wild. It is estimated that only 1% of hatchlings reach sexual maturity.
Each year on Ascension Island in the South Atlantic, C. mydas females create 6,000 to 25,000 nests. They are among the largest green turtles in the world; many are more than 3 feet in length and weigh up to 660 lbs.
Status: In recent decades, sea turtles have moved from unrestricted exploitation to global protection, with individual countries providing additional protection, although serious threats remain unabated. All populations are considered "threatened".
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Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. However, it is not a legal authority for statutory or regulatory purposes. While every effort has been made to provide the most reliable and up-to-date information available, ultimate legal requirements with respect to species are contained in provisions of treaties to which the United States is a party, wildlife statutes, regulations, and any applicable notices that have been published in the Federal Register. For further information on U.S. legal requirements with respect to protected taxa, please contact the U.S. Fish and Wildlife Service.
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