Sea turtles are air-breathing, warm water reptiles and are among the most ancient creatures on earth. They are protected by shells that consist of an upper part, or carapace, and a lower undersection, called the plastron. They cannot pull their neck and limbs into the shell like land turtles. Sea turtles are excellent swimmers using their long forelimbs as paddles. Sea turtles are also excellent divers, able to stay underwater for long periods of time.
Sea turtles obtain enough fresh water from their diet and from processing seawater.
They have a salt gland in their eyes that rids unneeded salt from their bodies. The beaks of sea turtles is perfect for what they eat, helping them crack the shells of crabs and snails. They have eardrums covered with skin, and hear best at low frequencies. They have a good sense of smell which helps them find seafood like shrimp and sea urchins. Underwater their vision is good, but they are nearsighted on land.