Leatherback Sea Turtle

Dermochelys coriacea

The largest living turtle and the heaviest reptile outside the crocodilians, reaching 2.7 m and 500 kg. It has no bony shell: the carapace is thick, oily, leather-like skin with minute bones embedded in it, raised into seven long ridges running the length of the back — the feature both the common and the scientific name describe. The front flippers span up to 2.7 m tip to tip, the largest of any sea turtle in proportion to the body, and the teardrop shape is the most hydrodynamic in the group. Leatherbacks swim almost constantly — tracked individuals may rest as little as a tenth of a percent of the day — and the heat that generates, trapped by insulating fat and counter-current heat exchangers, lets adults hold a core temperature up to 18 °C above the surrounding water. That is what allows a reptile to forage as far north as Alaska and Norway and into the Arctic Circle, and as far south as Cape Agulhas and southern New Zealand. They are among the deepest-diving animals in the ocean, recorded at 1,280 m, though a typical dive lasts only 3–8 minutes. Adults live almost entirely on jellyfish and other soft-bodied drifters, and Pacific animals cross roughly 9,700 km from Indonesian nesting beaches to feed off California; floating plastic bags pass for prey, and around a third of adults have swallowed plastic. Annual nesting females have fallen from an estimated 115,000 in 1980 to 26,000–43,000 today. The species is assessed as vulnerable, and several of its subpopulations are critically endangered.