The largest turtle, with no hard shell, which can survive in cool waters and dive deep in search of jellyfish and other food.

Statistics
Largest of the marine turtles, the leatherback may attain a total length of about 1.8m (6ft) with a weight of about 540kg (1,200lb) and a span of about 2.7m from the tip of one front flipper to the tip of the other.

Physical Description
Leatherbacks have no obvious shell. Instead bones are buried in their dark brown or blackish skin. Flexible bony plates are set on ridges. There are seven longitudinal ridges on the turtles' back and five on their underside. The flexible internal shell allows leatherbacks to withstand water pressure so they can dive to greater depths. They also differ from other turltes in that they do not have claws on their flippers.

Distribution
Leatherbacks are found in Pacific, Indian and Atlantic oceans, particularly tropical regions.

Habitat
They inhabit warm open seas throughout the world.

Diet
They feed primarily on jellyfish, and have backward-pointing spines in their throat to prevent prey escaping.

Behaviour
Leatherbacks are strong swimmers and undertake long journeys - tagged individuals have been known to cross the Atlantic. After nesting the females circle the site, possibly to reinforce it in their memory to aid return. The hatchlings also do this before heading to the sea. They are deep divers - perhaps reaching depths of 1,000m in search of food. They can hold their breath for up to half an hour. Leatherbacks are the most pelagic of turtles, feeding in the open ocean rather than near shore as other marine turtles do.

Reproduction
Like other turtles, leatherbacks leave the sea to dig burrows in the sand and lay eggs. They choose moonless nights to come ashore to avoid being seen by predators. The hatchlings have small pearly scales that disappear as they get older.

Conservation status
Leatherbacks are listed as Critically Endangered by the IUCN Red List.