Green sea turtle

The ocean voyager

A sea turtle lives 100 years and swims in the ocean all its life. But to lay eggs it returns to the very beach where it was born — travelling thousands of kilometres! Baby turtles hatch from the sand and run to the sea by moonlight. A turtle can't take off its shell — it's part of its skeleton.

The green sea turtle (Chelonia mydas) is a large turtle (up to 1.2 m, 150 kg) of tropical and subtropical oceans. It's named for the green colour of its fat. Adults are herbivores, grazing on seagrass and algae. Females first lay eggs at 20–30 years old and find their birth beach using Earth's magnetic field. Hatchlings' sex depends on sand temperature: warmer means female. Because of warming, 99% of hatchlings are female in some places. Threats: plastic (mistaken for jellyfish), fishing nets and beach development.

Fun facts

• Turtles navigate by Earth's magnetic field — they have a built-in compass.
• A hatchling's sex depends on sand temperature: warm means girl, cool means boy.
• A sea turtle can stay underwater for 5 hours without breathing.