Marine turtles represent an ancient and distinctive component of the world's biological diversity. It is believed that they first appeared more than 100 million years ago (TUCN, 1995). There are seven species of marine turtles living in the world representing two families, Cheloniidae and Dermochelyidae. These are the only living families of marine turtles descending from the large diverse marine radiation of cryptodiran turtles.
Cheloniidae is characterised by an extensively roofed skull with well-developed rhamphothecae while Dermochelyidae is characterised by the extreme reduction of bones of the carapace, plastron and the neomorphic epithecal shell layer consisting of a mosaic of thousands of small polygonal bones (Prichard, 1997).
The seven species include green turtle (Chelonia mydas), loggerhead turtle (Caretta caretta), hawksbill turtle (Eretmochelys imbrica1a\ olive ridley turtle (Lepidochelys olivaced) Kemp's ridley turtle (Lepidochelys kempii), flatback turtle (Natator depressus) and leatherback turtle (Dermochelys coriacea). There is an eighth species, the black turtle or east pacific green turtle (Chelonia agasszii) recognized.