Turtles are cool creatures, cold blooded reptiles who have hard shells to protect them from predators. Most turtles can hide their heads and entire bodies in their shells when attacked. Turtles have been around for 215 million years. Sea turtles drink salt water because of glands that can remove salt from saltwater. The largest turtle species are the leatherback sea turtles that can weigh up to 900 kilograms (2000 lbs).