Leatherback Turtle Sculpture – Marino las Baulas National Park, Tamarindo, Guanacaste Province, Costa Rica

The leatherback is the largest of living turtles and one of the largest reptiles in the world. Adults of this species can reach 1.83 m long and weigh 680 kg. (Pacific Ocean leatherbacks tend to be smaller than those of the Atlantic.) Its limbs are adapted to function well as paddles, and its head can partially retract into the shell. This turtle is distinct because it has a leathery shell with deep ridges. It does not have the strong epidermal shield that other turtles have, so the carapace and plastron are protected by a softer skin covering. This is the only marine turtle that lacks claws and large epidermal scutes over the shell. The upper surface is usually dark brown or black, occasionally with pale spots on the sides, throat, and neck. The underside of the body is mostly pale pink and white. Females may have a pink area on top of the head; hatchlings may be a bluish black with white along the edges.

The leatherback is a great wanderer and sometimes a single individual can be found quite far from the normal nesting migration. While it may seem tranquil, this turtle can be quite dangerous when bothered by using its flippers, jaws, and weight to fight back. The leatherback is built well for surviving the range of oceans it navigates. In deep or cold waters it can maintain a reasonable body temperature thanks to its large size and thick layers of fat and carapace. It can still swim because its circulation operates with a counter current heat exchange which helps pull blood away from the flippers and keep the rest of the body warm. It is also able to swim underwater for three hours on anaerobic respiration, and its brain can operate without oxygen for periods of diving.

An adult female will come up to sandy beaches to lay her eggs in a deep nest that she digs with her front flippers. She lays 45 to 100 eggs, fills in the pit and conceals the nest. She performs all of this at night, returning to the ocean before light. The sex of the new turtles is determined by temperature (TSD). When they are ready, the hatchlings dig their way to the surface of the beach and head immediately for the ocean. Not much is known about the behavior of this great reptile while they grow from hatchling to adult. Adults travel far between feeding and nesting grounds. They mate in the water before the females move towards the sand to start the next generation. Leatherback eggs are attacked by mammals (especially pigs and dogs), birds, and crabs; humans also poach the eggs which impacts the Leatherback's population. Their numbers have fallen to almost one-fifth of what they were in 1980. Hatchlings and juveniles are eaten by large fishes and sharks, but once the turtles reach adult size they have no predators besides humans.

The leatherback is a critically endangered species. It is protected by international policies and illegal to hunt. Read about Sea Turtles: Promises and Threats to learn more about the challenges facing this animal. Created in 1990 to protect Leatherback turtles from profit-making egg poachers, Marino las Baulas National Park is one of the foremost nesting sites for the leatherback turtle. The park protects 1,100 acres (445 hectares) of swampy mangrove coastline as well as 54,000 acres (21,850 hectares) of inland forest.