Found in US coastal waters

Green sea turtle

Chelonia mydas (Linnaeus, 1758)

Also called green turtle
Data updated October 2026

Green sea turtle swimming over a seagrass bed, showing its smooth olive-brown shell and small head
Fig. 1 — Adult swimming over seagrass, its main food once it settles near shore.
Close view of a green sea turtle's small head and serrated beak
Fig. 2 — A small head with a single pair of large scales between the eyes.

At a glance

The largest hard-shelled sea turtle and the only one that lives mainly on seagrass and algae as an adult. It is named for the greenish color of its body fat, not its shell. Green turtles nest on beaches from Florida to Hawaii and are protected under the Endangered Species Act.

01

Identification

Adult green sea turtles have a smooth, unridged, heart-shaped shell that is dark brown, gray or olive, often with darker mottling, over a yellowish to white underside. The head is small for the body and the beak has serrated edges. Between the eyes is just one pair of large scales, and the shell has five scutes down the middle and four along each side. Juveniles have bold, sunburst-like shell patterns and are often mistaken for hawksbills. Hatchlings are dark gray to black above and white below, with white edges on the shell and flippers.

  1. 01One pair of scales between the eyes. A key way to tell it from other hard-shelled sea turtles.
  2. 02Small head, serrated beak. The jaw edge works like a saw for cropping seagrass and algae.
  3. 03Four side scutes. Four large scutes on each side of the shell, none touching the scute behind the neck.

02

Size

01 ft2 ft3 ft4 ft5 ft6 ft Typical adult shell · about 3.5 ft (107 cm)

Adults are typically 3 to 4 feet (91–122 cm) long, measured along the shell, and weigh about 250 to 400 pounds; the US Fish and Wildlife Service puts the top weight at about 440 pounds. Young turtles leave the open ocean for coastal feeding grounds when their shell is only about 8 to 10 inches (20–25 cm) long.

03

Range & habitat

Green sea turtle grazing in shallow coastal water
Fig. 3 — Juveniles and adults feed in shallow, nearshore waters with seagrass and algae.

Green turtles live in tropical and subtropical seas around the world, and in parts of the temperate Atlantic, Pacific and Indian oceans and the Mediterranean. In US Atlantic and Gulf waters they occur inshore and nearshore from Texas to Maine, plus Puerto Rico and the US Virgin Islands. In the Pacific they live around Hawaii, American Samoa, Guam and the Northern Mariana Islands, and on the West Coast mainly from southern California south into Mexico.

Hatchlings spend several years in the open ocean, often among floating Sargassum, before moving to shallow coastal feeding grounds where they spend the rest of their lives. In New York, mostly juveniles turn up in eelgrass beds off eastern Long Island from about July to November. In the US, green turtles nest in Florida, Georgia, South Carolina, North Carolina, Puerto Rico, the US Virgin Islands, Hawaii, Guam, the Northern Mariana Islands and American Samoa.

State guides: Texas · Florida

04

Diet & predators

Young green turtles in the open ocean eat both plants and small animals from drifting communities such as Sargassum. Once they settle near shore, juveniles and adults feed mostly on seagrasses and algae, making them the only mainly herbivorous sea turtle. Adults also take sponges, other invertebrates and discarded fish when available, and green turtles in the eastern Pacific eat more animal food than other populations.

Feeds on

  • Seagrasses
  • Algae
  • Sponges and other invertebrates
  • Life in floating Sargassum (young turtles)

Preyed on by

  • Tiger sharks and other sharks
  • Killer whales
  • Large fish such as grouper and bass
  • Raccoons, feral hogs, foxes, crabs and ants (eggs and hatchlings)
Seagrass meadow in shallow clear water
Food — seagrass.
Tiger shark swimming over a sandy bottom
Predator — tiger shark.

05

Behavior & seasons

Like all sea turtles, green turtles breathe air and must surface regularly. They are solitary and migrate hundreds to thousands of miles between their feeding grounds and the nesting beaches where they hatched. In cooler waters, a sudden drop in temperature can leave them cold-stunned; in New York, cold-stunned turtles are mostly found in November and December.

Hatchlings find the sea by moving away from the dark outline of the dune toward the brighter horizon over the water, which is why bright beachfront lights can lead them inland.

06

Reproduction

Females mature at about 25 to 35 years and return every 2 to 5 years to nest on or near the beach where they hatched. In the US, the breeding season begins in late spring. Males mate with females on feeding grounds, along migration routes and off nesting beaches. A female comes ashore at night, digs a nest in the sand and lays about 110 eggs, and she may nest about every two weeks over several months. The eggs incubate for about two months. The largest nesting beaches in the world are Tortuguero in Costa Rica, Colola in Mexico and Raine Island in Australia.

07

Conservation

Green turtles were first listed under the US Endangered Species Act in 1978. Since 2016 the species has been split into 11 distinct population segments (DPSs). Three, the Central South Pacific, Central West Pacific and Mediterranean, are endangered. The other eight are threatened, including the North Atlantic DPS that uses US Atlantic and Gulf waters and the Central North Pacific DPS around Hawaii. New York also lists the green turtle as threatened.

Threats include bycatch in fishing gear, harvest of turtles and eggs in some countries, coastal development and lighting on nesting beaches, boat strikes, swallowed plastic and fishing line, hotter sand that can kill eggs or skew sex ratios, and fibropapillomatosis, a disease that causes tumors. See all US endangered and threatened reptiles

Keep reading

Sources

Data updated October 2026 · How we build these pages