sea turtle

sea turtle
Name	Sea turtle
Taxon	Chelonioidea
Authority	Schweigger, 1812

sea turtle. Sea turtles are marine reptiles belonging to the superfamily Chelonioidea, comprising seven extant species. They are characterized by their streamlined shells and large, paddle-like flippers adapted for life in the ocean. These ancient creatures have existed for over 100 million years, surviving the Cretaceous–Paleogene extinction event that wiped out the non-avian dinosaurs.

Description and anatomy

All sea turtles share a fundamental body plan with a bony or cartilaginous shell, which includes a dorsal carapace and a ventral plastron. The leatherback sea turtle is unique, possessing a leathery, ridged carapace instead of a hard, keratinous shell. Their limbs are modified into long, wing-like flippers, with the front pair providing powerful propulsion and the smaller hind pair acting as rudders. Species like the loggerhead sea turtle and the hawksbill sea turtle have distinctive beak shapes adapted to their specific diets. Internally, they possess specialized salt glands near their eyes to excrete excess salt ingested from seawater, an adaptation shared with other marine reptiles like the marine iguana.

Distribution and habitat

Sea turtles inhabit all the world's oceans except the polar regions, with their range extending from the tropical waters of the Caribbean Sea and the Great Barrier Reef to more temperate zones like the Mediterranean Sea and the coastal waters of New England. The leatherback sea turtle has the widest distribution, with recorded migrations into the cold waters of the North Atlantic and near Alaska. Critical habitats include nesting beaches, often on remote, sandy shores such as those in Costa Rica, Oman, and Raine Island, as well as productive foraging grounds like seagrass beds and coral reef ecosystems.

Life cycle and reproduction

Female sea turtles exhibit remarkable natal homing, returning to the region of their own birth to nest, often on beaches like those at Tortuguero National Park or Gahirmatha Beach. After digging a nest chamber, they lay a clutch of leathery eggs before covering them and returning to the sea. Incubation temperature determines the sex of the hatchlings, a phenomenon known as temperature-dependent sex determination. After emerging, hatchlings undertake a frenzied dash to the ocean, facing predators like ghost crabs and frigatebirds. They then enter a pelagic developmental phase, often drifting in currents like the Gulf Stream or the North Pacific Gyre, before eventually recruiting to coastal habitats as juveniles.

Diet and feeding behavior

Diet varies significantly among species. The green sea turtle is primarily herbivorous as an adult, grazing on seagrasses and algae in ecosystems such as those found in Florida Bay and Shark Bay. The hawksbill sea turtle uses its narrow, pointed beak to probe crevices in coral reefs for sponges and other invertebrates. The loggerhead sea turtle possesses powerful jaws for crushing hard-shelled prey like mollusks, crabs, and sea urchins. The massive leatherback sea turtle is a specialist feeder on jellyfish and other soft-bodied zooplankton, which it captures using backward-pointing spines in its esophagus.

Conservation status and threats

All seven species face significant threats and are listed on the IUCN Red List, with the Kemp's ridley sea turtle and hawksbill sea turtle being critically endangered. Major anthropogenic threats include bycatch in fisheries such as longline fishing and gillnet operations, direct harvesting of eggs and adults, and coastal development that destroys nesting beaches. Pollution, particularly plastic pollution which can be mistaken for jellyfish, and climate change, which alters sand temperatures and thus sex ratios, pose severe long-term risks. International protection efforts are coordinated under agreements like the Convention on International Trade in Endangered Species of Wild Fauna and Flora and regional bodies like the Inter-American Convention for the Protection and Conservation of Sea Turtles.

Cultural significance

Sea turtles hold profound cultural importance in many societies worldwide. In Hawaiian mythology, the turtle, or *honu*, is considered an *aumakua* (family guardian spirit). In Japanese folklore, there are tales of grateful turtles, such as in the story of Urashima Tarō. For the Māori people of New Zealand, turtles appear in creation stories. They have been featured prominently in modern media, including the character Crush in the Pixar film *Finding Nemo*, and are central to ecotourism industries in places like the Galápagos Islands and the Seychelles.

Category:Sea turtles Category:Marine reptiles Category:Symbols of Florida