The Green Sea Turtle (Chelonia Mydas) is the largest of all the hard-shelled sea turtles, growing to more than 3 ft (0.91m) long. Like all reptiles, Green Sea Turtles are cold-blooded. They evolved a bony outer shell which covers both the dorsal (back) and ventral (belly) surfaces with a highly developed protective armor. Sea turtles have the perfect body structure for life in the ocean. They can reach a speed of 35 mph, and their flippers make them graceful, efficient swimmers. Green Sea Turtles are herbivores named for the color of their body fat, which derives from their diet of algae and sea grasses. However, when young they are carnivorous, eating jellyfish and other invertebrates.