Most widely distributed reptile

The most widely distributed reptile is the leathery (leatherback) turtle (Dermochelys coriacea), the largest living species of marine turtle. Its zoogeographical distribution ranges as far north as Norway and Alaska, USA, well within the Arctic Circle, to as far south as Cape Agulhas, South Africa, and the southernmost tip of South Island, New Zealand, well below the Tropic of Capricorn, thereby constituting a latitude span of approximately 115°. Moreover, it occurs in all tropical and subtropical oceanic regions.

The leathery turtle has many additional claims to fame and records. It is the only living species of turtle to lack an external bony shell, instead possessing a carapace consisting of tiny bony plates embedded within a thick, oily, leathery skin. It is able to survive in far colder environments than other marine turtles because its very high activity continuously generates heat in a manner analogous to true endothermy, assisted by its thick layer of insulating body fat plus a specialized blood vessel structure known as a countercurrent exchanger.

It is the only surviving member of its taxonomic family (all other living turtle species belong to a separate, second family) and is little different in overall form from related fossil species dating back more than 100 million years. And despite its great size, it lives almost exclusively upon a diet of jellyfishes, whose predominantly watery composition one might imagine to be too insubstantial both physically and nutritionally to sustain such a creature.