Millions of years ago, the oceans were filled with many diffrent types of horseshoe crabs. Today there are only 5 species left. Limulus polyphemus lives at the edge of the ocean, along the Atlantic coast from Canada to the Gulf of Mexico. It is the only horseshoe crab in the Atlantic Ocean. The others live off the coast of Asia.

The horseshoe crab has a thick body shell shaped like a horseshoe. It also has a long tail that trails behind it. From below you can see 5 pair of legs ending in little claws. It is called the horseshoe crab because it has a general body shape similar to the crab. But it isn't a crab at all! In fact, it's more closely related to scorpions and spiders.

It finds its food-mollusks and worms-in the sand. When it has to move, its long tail works like a lever to help push it out of the sand. The tail also helps it put itself back on its legs when it has been turned over by a large wave. In the water, the horseshoe crab swims easily on its back.

When it's time to lay their eggs, males and females cross the sand to get to the highest part of the beach. The female digs a hole and lays up to 10,000 eggs. The eggs hatch in about two weeks and young horseshoe crabs reach the sea with the help of the rising tide.