Sea Turtles

Sea Turtles

Introduction Sea turtles have roamed the oceans for at least 150 million years. They are among Earth's oldest surviving animals, having lived during the time of the dinosaurs. Like dinosaurs, sea turtles are reptiles, and like all reptiles, sea turtles are cold-blooded. They have scaly skin, breathe air, and have a heart with three chambers.

Sea turtles have many living turtle relatives, including freshwater turtles, snapping turtles, tortoises, and soft-shelled turtles. All of these turtles live either on land or in fresh water. Sea turtles are the only turtles that live in the salt water of the world's oceans.

Types of Sea Turtles Sea turtles are divided into two types. One type, called the leatherback, is covered with leathery skin. Beneath this skin is a shell made of cartilage and thousands of tiny bones. The cartilage forms prominent ridges that give the leatherback its unique appearance. The leatherback is the largest of all sea turtles and the most widely distributed. It lives far out at sea except during breeding season.

All types of sea turtles other than the leatherback have a shell made of bony plates, or scutes. The top part of the shell is called the carapace. The part of the shell under the turtle's belly is called the plastron. These two parts are connected to the muscles and bones inside the turtle's body. The number and pattern of the scutes is helpful in identifying the type of sea turtle.

The green turtle is a medium to large sea turtle with a shell that has mottled markings. The green turtle's head is small relative to its body when compared with other sea turtles. It lives in many oceans around the world. The black turtle is sometimes called the Pacific green turtle. Researchers disagree on whether it is a type of green turtle. The black turtle is dark gray with stripes of other dark colors. It lives on the west coasts of North and South America. The black turtle prefers to live in warm bays and protected shores, and is rarely found in the open ocean.