The green sea turtle is named for its fat, not its shell color.

Nature · Published 30 September 2026 Swipe more like this →

In short: While their carapaces range from olive to black, the green sea turtle earns its name from the greenish fat stored beneath its shell. This unique coloration is a direct result of their specialized, mostly herbivorous diet of seagrasses and algae, which distinguishes them from other sea turtle species.

The green sea turtle, Chelonia mydas, is the only herbivorous aquatic turtle species once it reaches maturity. While hatchlings and juveniles are carnivorous, consuming small invertebrates and fish, adults transition to a diet of seagrasses and algae. This shift in diet is reflected in their anatomy; they possess a serrated jaw specifically adapted for chewing vegetation, and their body fat turns green due to the pigments in the plants they consume.

These turtles are highly migratory, often traveling thousands of kilometers between feeding grounds and the specific beaches where they were born. This behavior, known as natal homing, ensures they return to environments that have historically provided reproductive success. Females typically nest every two to four years, digging deep holes in the sand to deposit clutches of 85 to 200 eggs. The sex of the hatchlings is determined by the temperature of the nest during the incubation period, with warmer temperatures producing females and cooler ones producing males.

Despite their resilience—some individuals live up to 90 years—the species faces significant threats. Only about 1% of hatchlings are estimated to reach sexual maturity, as they are vulnerable to predators like crabs and shorebirds during their initial scramble to the ocean. Adults are threatened by habitat loss, pollution, and accidental capture in fishing nets. Furthermore, they are susceptible to fibropapilloma, a disease caused by a herpesvirus transmitted by leeches, which can lead to lethal tumor growth. While global populations are protected by law, the species remains a subject of ongoing conservation efforts across more than 140 countries.

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