Sea Turtle

MarineReptileLong-lived

Overview

Sea turtles are large marine reptiles of the superfamily Chelonioidea, with seven recognised species adapted to life in the ocean. This page is a group-level overview; the green sea turtle (Chelonia mydas) is used as a familiar reference. Sea turtles have streamlined shells and flipper-shaped limbs for swimming. They breathe air, are long-lived, and return to land only to lay eggs.

Habitat & Range

Sea turtles live in tropical and temperate oceans worldwide, using habitats such as coastal seas, coral reefs, seagrass beds, and the open ocean at different life stages. They are highly migratory, and many travel long distances between feeding grounds and the beaches where they nest. Females return to sandy beaches — often near where they hatched — to lay their eggs.

Diet

Diet varies by species. Green sea turtles are unusual in that adults feed largely on seagrasses and algae, while other species specialise differently — for example, hawksbills feed heavily on sponges, loggerheads on hard-shelled invertebrates, and leatherbacks almost entirely on jellyfish. Young sea turtles are often more omnivorous than adults. Diet should be described per species rather than for sea turtles as a whole.

Behavior

Sea turtles are strong, graceful swimmers that spend almost their entire lives at sea. They are known for remarkable long-distance navigation between feeding and nesting areas. Females come ashore at night to dig nests and lay clutches of eggs in the sand; the hatchlings later emerge together and make their way to the sea. Hatchling sex in many species is influenced by the temperature of the nest.

Human Interaction & Conservation

Sea turtles face significant threats from habitat loss, coastal development, entanglement and bycatch in fishing gear, pollution including plastics, the harvesting of eggs and animals, and climate change affecting nesting beaches. Several species are considered threatened and are protected under national and international law. Because status differs by species and is actively monitored, it should always be verified against current IUCN Red List and government sources.

Appearance & Recognition

Sea turtles have a broad, streamlined shell (carapace) and paddle-like front flippers that power their swimming, unlike the clawed feet of land and freshwater turtles. They cannot retract their head and limbs into the shell. Species are told apart by features such as shell shape and the pattern of scales on the head; the leatherback is distinctive in having a leathery, ridged shell rather than a hard, scaly one.

Similar Animals

Sea turtles are reptiles, related to the freshwater and land turtles covered separately on FaunaHub under the turtle profile, but they are specialised for ocean life with flippers instead of feet. They should not be confused with marine mammals; sea turtles are air-breathing reptiles that lay eggs on land.

More photos of the sea turtle

A green sea turtle swimming upward toward the surface. — A green sea turtle rising for air.
Image: Brocken Inaglory, CC BY-SA 3.0, via Wikimedia Commons.

Frequently Asked Questions — Sea Turtle

How many species of sea turtle are there?

Seven are generally recognised: the green, loggerhead, hawksbill, olive ridley, Kemp's ridley, flatback, and leatherback sea turtles. They differ in size, diet, range, and conservation status, so this page is a group-level overview.

Why do sea turtles come onto beaches?

Adult sea turtles spend their lives at sea, but females come ashore to nest. They haul out onto sandy beaches, usually at night, dig a nest, and lay a clutch of eggs before returning to the ocean. The hatchlings later emerge and head to the sea.

Are sea turtles endangered?

Several sea turtle species are considered threatened and are legally protected, but the situation differs by species and population. Because status is actively monitored and can change, it should be checked against current IUCN Red List and government (such as NOAA Fisheries) sources rather than assumed.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.

UniversityAnimal Diversity Web — Chelonia mydas (green sea turtle) — University of Michigan species account
GovernmentNOAA Fisheries — Green Sea Turtle — U.S. government species page for the green sea turtle
Wildlife referenceIUCN Red List of Threatened Species — Authoritative source for current conservation status