green sea turtle

green sea turtle is a large, herbivorous sea turtle belonging to the family Cheloniidae. It is the only species in the genus Chelonia and is distinguished by its smooth, heart-shaped carapace. These reptiles are found in tropical and subtropical oceans worldwide, with major nesting sites on beaches such as those on Raine Island and in Tortuguero National Park. The species is classified as Endangered by the International Union for Conservation of Nature due to numerous anthropogenic threats.

Description and taxonomy

The species was first formally described by Carl Linnaeus in his seminal work Systema Naturae. Its common name derives from the greenish color of its subcutaneous fat, not its shell. Adults possess a streamlined carapace, which can reach over a meter in length, and paddle-like flippers adapted for powerful swimming. The Pacific subspecies, Chelonia mydas agassizii, is sometimes recognized, though taxonomic debate continues. Key distinguishing features from other sea turtles, like the loggerhead sea turtle or hawksbill sea turtle, include a single pair of prefrontal scales and a serrated lower jaw.

Distribution and habitat

Green sea turtles have a circumglobal distribution, inhabiting the Atlantic Ocean, Indian Ocean, and Pacific Ocean. They are commonly associated with coral reefs, seagrass meadows, and estuaries in regions such as the Great Barrier Reef, the Hawaiian Islands, and the Caribbean Sea. Important foraging grounds exist in places like Florida Keys National Marine Sanctuary and Shark Bay. Major nesting rookeries are located on beaches in Oman, Costa Rica, and on Ascension Island, where females exhibit strong natal homing.

Ecology and behavior

Adults are primarily herbivorous, feeding almost exclusively on seagrass and algae, which shapes the ecology of their foraging habitats. Juveniles are more omnivorous, consuming jellyfish, crustaceans, and other invertebrates. They are known to undertake long-distance migrations between feeding and nesting sites, often navigating using the Earth's magnetic field. Predators of hatchlings include ghost crabs, frigatebirds, and various shark species. The turtles are also known to host epibionts like barnacles and provide cleaning opportunities for fish such as blue-streak cleaner wrasse.

Life cycle and reproduction

Females return to their natal beaches every two to four years to nest, a behavior studied extensively at locations like Tortuguero National Park. A single clutch can contain over 100 eggs, which are deposited in a nest chamber dug in the sand. Incubation, influenced by sand temperature, typically lasts around two months, with warmer temperatures producing more females—a phenomenon known as temperature-dependent sex determination. After hatching, neonates embark on a frenzied dash to the sea, entering a pelagic phase often called the "lost years" before recruiting to coastal habitats.

Conservation status and threats

The species is listed as Endangered on the IUCN Red List and is protected under various international agreements including CITES and the Convention on the Conservation of Migratory Species of Wild Animals. Primary threats include bycatch in gillnet and trawl fisheries, direct harvest of eggs and adults, habitat destruction of nesting beaches from coastal development, and fibropapillomatosis disease. Conservation efforts are led by organizations like the World Wildlife Fund and involve protecting critical nesting beaches in places such as Raine Island and reducing fisheries interactions through the use of turtle excluder devices. Climate change poses a long-term threat through sea level rise and increased sand temperatures affecting sex ratios.

Category:Sea turtles Category:Reptiles described in 1758