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Green Sea Turtle, Chelonia mydas, Family Cheloniidae, Pictures, Stock Photos, Images

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The Green Sea Turtle, Chelonia mydas, gets its name from the greenish color of its flesh, not from its shell, which is usually brownish. It is the largest of the hard shelled sea turtles, and is characterized by its small head, serrated lower jaw, and the long tails of the mature males. It is the only sea turtle species that regularly basks on sandy beaches, and it may be the fastest swimming sea turtle, with speeds of 24 km (14 miles) per hour.

The Green Sea Turtle is a large sea turtle with a weight of 80-220 kg (175 to 485 lbs) and a carapace length of from 80 to 120 cm (30 to 47 in) (Witherington, 2006). Females have a short tail that reaches just to the edge of the carapace, while the tails of males are much longer.

The coloring of Green Sea Turtles varies from olive, to brown, to black (see also Black Sea Turtle, Chelonia mydas agassizi, yellow, and creamy-white. They have beautifully patterned shells, though the markings are usually not as bold as those of hawksbill sea turtles. The underside, or plastron, ranges in color from yellow to olive-gray. Green Sea Turtles have one claw on each front flipper, and one pair of prefrontal scales. Like the Hawksbill Sea Turtle, Eretmochelys imbricata, they have 4 pairs of lateral scutes, distinguishing them from Loggerhead Sea Turtles, Caretta caretta, which have five. The Green Sea Turtle’s serrated lower jaw is unique among sea turtle species.

Green Sea Turtles are mainly found in tropical and subtropical waters throughout the world, but they are sometimes seen in temperate areas as well. Sightings have been recorded in 140 countries. Important feeding areas are the coasts of Nicaragua, Brazil, Oman, Vanuatu, Fiji, Japan, Baja California, and the Pacific coast of South America. Nesting areas are more strictly confined to 20 degrees north and south of the equator. Green Sea Turtles are generally migratory, but the individuals found in Hawaii and the Galapagos spend their entire life cycles near their place of birth.

While most sea turtles only go ashore to nest, green sea turtles are known to bask on sandy beaches, both during the day and at night. This behavior is particularly noticeable in Hawaii and the Galapagos, and occasionally in Australia and Mexico. The purpose of this basking is not completely understood, but it may serve several purposes. It may be a time of rest for the turtles; it may serve to raise the body temperature, causing eggs to mature faster as well as speed up digestion; it may add vitamin D to their systems; and it may contribute to health of the skin by killing parasites and fungus.

 

Green Sea Turtle Cleaned by Various Reef Fish
Picture of Endangered green sea turtle, Chelonia mydas, being cleaned by Yellow Tang, Zebrasoma flavescens, Gold-ring Surgeonfish, Ctenochaetus strigosus, and endemic Saddle Wrasse, Thalassoma duperrey, off Kona Coast, Big Island, Hawaii, Pacific Ocean. Image #: 020965

Kingdom: Animalia

Phylum: Chordata

Subphylum: Vertebrata

Class: Reptilia

Order: Testudines

Suborder: Cryptodera

Superfamily: Chelonioidea

Family: Cheloniidae

Genus Species: Chelonia mydas

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The diet of Green Sea Turtles varies as they progress from juvenile to adult. As pelagic phase juveniles, they subsist mainly on jellyfish and other soft-bodied invertebrates. As adults, they become vegetarian, subsisting mainly on sea grasses and algae, which they digest with the aid of bacteria in their gut. Their serrated lower jaw is useful for cutting off the blades of sea grasses. Young grasses contain more nutrients, so turtles keep feeding areas well-mowed, which encourages the growth of nutritious new grasses.

Like most sea turtles, Green Sea Turtles travel great distances-over a thousand miles-from feeding grounds to the beaches they were born. They mate in the water close to where they will nest. The single claw on each flipper and the flat nail on the tail of the male are used for grasping the female during mating. Females lay their eggs at night in clutches of 110-115 golf ball-sized eggs. Eight or nine clutches per breeding season are laid at intervals of two weeks, and incubation lasts 55 to 60 days.

Green Sea Turtle hatchlings weigh about 25 g (1 oz.). They quickly enter the ocean and are rarely seen during their early pelagic phase. Their size increases rapidly in their early years when they feed on animal protein, but slows down later as they age and begin to feed on sea grasses and algae. Full maturity is reached at the advanced age of from 20 to 50 years.

Unfortunately for the Green Sea Turtle, and in contrast to the Hawksbill Sea Turtle, its meat is considered particularly tasty. The oil and fat in the meat has a green hue, which gave the Green Sea Turtle its name. In some parts of the world, cartilage from its plastron, called calipee, is scraped off slaughtered turtles to make the delicacy, green turtle soup. Green Sea Turtles are even commercially farmed in the Cayman Islands as food for locals.

Like all sea turtles, Green Sea Turtles face degradation of habitat, harvest of their eggs, capture in fishing nets, and death by predators. The IUCN lists the Green Sea Turtle as Endangered, except for in the Mediterranean region, where it is Critically Endangered. While their nesting sites are currently protected in many parts of the world, Green Sea Turtles are subject to other dangers that may be difficult to protect against. They are known to suffer from a tumor-like disease called fibropapillomatosis, which causes wart-like growths to appear on their skin, particularly around their eyes. These growths impede eyesight and movement, making it more difficult for them to survive.

Other common names: Green Seaturtle, Edible Turtle, Soup Turtle, Greenback Turtle, Tortuga Verde (Spanish) (Witherington, 2006)

For a diagram helpful in identifying the green sea turtle, see http://marinebio.org/species.asp?id=51

• Green Sea Turtle information assembled from published and on-line sources by Kevin Miller on Dec. 31, 2006 for Seapics.com.

Sources:

Perrine, D. Sea Turtles of the World, Voyageur Press, 2003

Ripple, J. Sea Turtles, Voyageur Press, 1996

Witherington, B. Sea Turtles, Voyageur Press, 2006