The green turtle (Chelonia mydas) is one of the largest and most widespread of all the marine turtles. The oval carapace varies from olive to brown, grey and black with bold streaks and blotches, but the common name, green turtle, is derived from the green colour of the fat and connective tissues of this species. Two subspecies are traditionally recognized; the Pacific green turtle (Chelonia mydas agassizii) tends to be smaller than its Atlantic cousin (Chelonia mydas mydas) with a narrower carapace that may sometimes be completely black, providing the other common name of 'black turtle' to certain populations. The plastron, or undershell, of the green turtle remains a pale yellow or orange throughout life. Males are generally smaller than females, and the green turtle differs in appearance from other marine turtles by the possession of a single pair of scales in front of the eyes and a serrated bottom jaw. The tiny black hatchlings are only around 5 centimetres long.