The green sea turtle (Chelonia mydas), also known as the green turtle, black (sea) turtle, or Pacific green turtle, is a large sea turtle of the family Cheloniidae. This species is named for the green color of its fat, rather than the color of its skin of shell as most people think. These turtles shells are in fact olive to black. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans. The common name comes from the usually green fat found beneath its carapace.