Sea turtles are divided into two families. Members of one have horn shells; members of the other have leathery shells. Sea turtles possess flippers instead of claws and cannot withdraw their heads into their shells. They are found in warm seas worldwide.The green sea turtle weighs up to 500 pounds with a shell up to 50 inches long.
Most sea turtles have hard shells that are like suits of armor. A hard shell is made up of several plates. These plates fit together like pieces in a jigsaw puzzle. They make the shell firm and tough. Even a shark’s razor-sharp teeth can’t bite through it.
The curved shell on a sea turtle’s back is called the carapace (KAR uh pays). A sea turtle doesn’t just have a shell on its back, though. It also has a shell called the plastron (PLAS truhn) that covers its belly. On most turtles, hard scales cover the parts of the body that are not protected by the shell.
The shell has openings for the turtle’s head, tail, and legs. Sea turtles have legs shaped like long paddles, with flippers instead of feet.
Sea turtles, like all turtles, are toothless. But they do have ridges, or bumps, along both their upper and lower jaws. These ridges are pointy and sharp. They help a turtle cut its food into small pieces before swallowing.
Most sea turtles feed on small sea animals, such as sponges. They also feed on sea plants and grasses. But some sea turtles eat mostly plants, and some eat mostly meat.
A sea turtle that feeds mostly on plants has jaws that look like the edge of a saw. This helps the turtle tear off pieces of tough plants. Meat-eating sea turtles have ridges that are as sharp as knives. With their jaws, they can slice into their prey.
Besides being sharp, the jaws of turtles are strong. Meat-eating sea turtles often use their jaws to grab passing fish. Once these turtles clamp down tightly, their prey can’t slip away.
A sea turtle’s senses are very sharp. This reptile’s sense of smell is its strongest sense. Some scientists believe that a sea turtle has a stronger sense of smell than a dog has. A sea turtle uses its keen nose to find prey and to smell a nearby enemy.
A sea turtle can hear well, too. But where are the ears of this green turtle? Sea turtles have eardrums that are covered by skin. With these eardrums, sea turtles can hear low-pitched sounds about as well as a person can hear them. The eardrums also help sea turtles detect vibrations along the ground or in the water.
Sea turtles also have good eyesight. They can see clearly when they are swimming through the water. Their eyes help them spot small prey in the open seas.
On land, sea turtles are very slow. But, in the water, they’re fast. Green turtles, like the one you see here, can zip through the water at nearly 20 miles (32 kilometers) per hour.
Sea turtles have powerful front legs. These legs are long. They are also wide and flat at the end—just like paddles. Sea turtles use their strong front legs as paddles to glide swiftly through the water.
The sea turtle’s shell helps it swim fast, too. Its shell is flatter and smaller than most other turtle shells. It’s the perfect shape to cut through the water with the least amount of effort.
A sea turtle’s small shell does have a drawback, though. Unlike many other turtles, a sea turtle can’t pull its head and legs inside its shell to hide from its enemies. Instead, a sea turtle must depend on speedy swimming to get away.
Since sea turtles are cold-blooded, they need to stay in warm waters all year long. So when the temperature starts to drop, they migrate, or travel long distances, to warmer waters. Some sea turtles have to travel hundreds, or even thousands, of miles just to keep warm.
Sea turtles, including loggerheads, migrate for another reason, too. Female sea turtles leave the waters where they feed to travel to a nesting ground. This is where they will eventually lay their eggs. Once the females lay their eggs, they journey back to their feeding grounds.
The open sea doesn’t have any landmarks. So how do migrating sea turtles know where to go? Some scientists think that sea turtles may use the sun, the moon, and the stars to guide them.
All turtles—whether they live on land, in fresh water, or in the sea—lay their eggs on land. Sea turtles lay their eggs on sandy beaches.
Many female sea turtles have what is called a homing instinct. This means that they return to the beach where they were born to lay their eggs. Laying eggs on land is hard work for a female sea turtle. When swimming, a female can glide through the water with ease. But on a beach, she must slowly drag herself across the sand.
A female sea turtle looks for a spot that will be safe at high tide. Once she finds a safe spot, she digs a hole in the sand with her back feet. The female then lays her eggs inside the hole and covers them with sand. When she is finished, she heads toward the water and back out to sea.
A nest of turtle eggs is called a clutch. A female sea turtle may lay over 100 eggs in just one clutch! And she may lay six or more clutches in a season. Altogether, this may add up to 1,000 eggs. But most sea turtles lay far fewer eggs than that. The average is about 400 eggs in a season.
A sea turtle’s egg is usually about the size and shape of a Ping-Pong ball. Its shell is not brittle like a bird’s egg. Instead, it’s tough and springy. It needs to be, especially if it’s at the bottom of a 100-egg pile.
Over time, the sand incubates (IHN kyuh bayts), or warms, the eggs. This helps the baby turtles grow inside the safety of their shells until they are ready to hatch. Most sea turtles hatch after about two months of incubation.
A clutch of hatchlings, or baby sea turtles, all dig their way out of their nest at the same time. Each tiny hatchling weighs about as much as a pencil and can fit in the palm of your hand.
The newborn turtles leave their nest at night. Without parents to protect them, the hatchlings must fend for themselves. Even in the darkness, many animals, such as sea gulls and crabs, prey on hatchlings. So the baby turtles must scurry across the open beach and into the water—fast.
When baby turtles reach the water, they have a long trip ahead. They must swim far out to the safer waters of the open sea. There they remain until they are young adults. Then most sea turtles return to shallow waters along the coast, where they live for most of their lives.Young turtles find their way to the water by themselves.
The most dangerous part of a sea turtle’s life is its first 10 years. During those years, the turtle is small and not very fast. If it survives this period, it can live a long life. Some kinds of sea turtles can live to be 80 years old. Other turtles can live even longer than that. In fact, some turtles live longer than many other creatures with backbones—including humans.