Green Sea Turtles (Chelonia mydas) typically weigh between one and two hundred pounds and are found throughout the warm waters of the world.  Their hard shell varies in color from black to green to yellow.  The variety found in the Galapagos tend to be browner than their continental cousins, but they are still considered to be the same species and interbreeding between the two varieties is thought to occur.  They feed primarily on seaweed, and spend large periods of time underwater, resting on shallow sandy bottoms.