Green Sea Turtle

The green sea turtle (Chelonia mydas) is a large sea turtle of tropical and subtropical oceans, named for the green color of its fat. Adults graze on seagrass and algae. In October 2025 the IUCN reassessed it as Least Concern globally after decades of nest protection let many populations recover, though some regional populations remain at risk.

🧬 Field Guide Specimen: Open Green Sea Turtle in the CRV Science Field Guide to log the specimen, see its place among the Reptilia lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.

Females return to nest on or near the beach where they hatched, often after migrations of thousands of kilometers. Studies suggest turtles detect the intensity and inclination of Earth's magnetic field as a kind of map signature of their natal coast.

Like many reptiles, the sex of hatchlings depends on nest temperature, with warmer nests producing females. Climate warming has produced nesting populations that are overwhelmingly female in some places, such as parts of the Great Barrier Reef. See Climate change.

Green turtles cut seagrass and so influence the health and productivity of the meadows. Threats include fisheries bycatch, loss of nesting beaches, plastic pollution and the viral disease fibropapillomatosis.

• Climate change — warming sand and skewed sex ratios
• Sea-level rise — loss of nesting beaches