Sea turtle

Sea turtles (Chelonioidea) are turtles found in all the world's oceans except the Arctic Ocean, and some species travel between oceans. The term is US English. In British English they are simply called “turtles”; fresh-water chelonians are called “terrapins” and land chelonians are called tortoises.

Sea turtles
Sea turtle
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Order:	Testudines
Suborder:	Cryptodira
Superfamily:	Chelonioidea Bauer, 1893
Genera
Family Cheloniidae (Oppel, 1811) Caretta Chelonia Eretmochelys Lepidochelys Natator Family Dermochelyidae Dermochelys Family Protostegidae (extinct) Family Toxochelyidae (extinct) Family Thalassemyidae (extinct)

The earliest known turtles are from the Middle Jurassic. This makes turtles the oldest surviving reptile groups: they are more ancient than snakes or crocodiles. ^[1]

There are seven species of sea turtle: Kemp's Ridley sea turtle, the olive Ridley, the flat back, the green, the loggerhead, the hawk's bill and the leatherback.

All but the leatherback are in the family Chelonioidea. The leatherback belongs to the family Dermochelyidae and is its only member. The leatherback sea turtle is the largest, measuring six or seven feet (2 m) in length at maturity, and three to five feet (1 to 1.5 m) in width, weighing up to 2000 pounds (907.18 kg) (about 900 kg). Most other species are smaller, being two to four feet in length (0.5 to 1 m) and proportionally less wide. The flatback turtle is found only on the northern coast of Australia.