There are six species.

weighs up to 500 pounds (225 kg) with a shell up to 50 inches (127 cm) long. It feeds mainly on plants. Green turtles are found in warm seas worldwide. They can migrate more than 1,000 miles (1,600 km) from where they were hatched, returning six to eight years later to lay their eggs. They are hunted for their meat.

native to Australia, is the only species of sea turtle not in danger of extinction. It is similar in appearance and size to the green turtle.

weighs up to 175 pounds (80 kg) with a shell about 35 inches (89 cm) long. It is found primarily in warm waters of the Atlantic and Pacific oceans. The hawksbill is hunted for its patterned shell, which is made into decorative items.

The hawksbill is a colorful sea turtle that lives in warm tropical waters. This turtle has a pointed beak that looks like a hawk’s bill. That’s how this reptile got its name.

Unlike other sea turtles, the hawksbill has two claws on each flipper. It often uses its claws to stir up sponges that live along the ocean floor or in coral reefs. Hawksbills feed on sponges whenever they get a chance. In fact, hawksbills like sponges so much that they rarely eat anything else.

weighs up to 450 pounds (204 kg) and has a shell about 45 inches (114 cm) long. It has powerful jaws, which it uses to crack open mollusks. Loggerheads are found in warm and temperate seas worldwide.

There are also two species of ridleys, the Altantic ridley (also called Kemp's ridley) and the Pacific (or olive) ridley. The ridleys are the smallest of the sea turtles. They weigh up to 100 pounds (45 kg) with a shell up to 28 inches (71 cm) long. The Atlantic ridley has only one major nesting area, a small stretch of beach in Mexico.

This turtle has leathery skin instead of a horn layer of shell. Its shell has no true bony layer, but irregular pieces of bone are embedded in the skin layer. Leatherbacks are the largest of all turtles, averaging 7 feet (210 cm) in length and 1,000 pounds (450 kg) in weight. In the summer, they are found as far north as British Columbia and Nova Scotia, and in the winter, as far south as southern Argentina and South Australia. They can dive to more than 3,000 feet (900 m). There is only one living species of leatherback.

The leatherback is the only species of turtle that lives in the sea and does not have a hard, bony shell. Its shell is covered instead with a soft, leathery skin.

The leatherback is also the largest of all turtles. This sea giant can be 8 feet (2.4 meters) long. The span of its front flippers is even longer than that. And it can weigh more than 1,500 pounds (680 kilograms).

Most sea turtles stay in warm coastal waters. Leatherbacks, however, often go into deep northern waters off Canada and Europe and into the cool southern waters off Argentina. That’s where they can find plenty of their favorite food—jellyfish.