Description:

Turtles are reptiles of the order Chelonii[2] or Testudines characterised by a special bony or cartilaginous shell developed from their ribs and acting as a shield.[3] Turtle may refer to the chelonian order as a whole (American English) or to fresh-water and sea-dwelling chelonians (British English).[4] The order Chelonii or Testudines includes both extant (living) and extinct species. The earliest known turtles date from 220 million years ago,[5] making turtles one of the oldest reptile groups and a more ancient group than lizards, snakes or crocodiles. Of the many species alive today, some are highly endangered.[6] Like all other extant reptiles, turtles are ectotherms—their internal temperature varies according to the ambient environment, commonly called cold-blooded. However, because of their high metabolic rate, leatherback sea turtles have a body temperature that is noticeably higher than that of the surrounding water.