There is an animal called cancer

Limulus polyphemus Horseshoe Crab


What do horseshoe crabs look like?

Horseshoe crabs are hardly like any other animal we know.

Your shield-shaped front body and the trapezoidal rear body are each covered by an armor-like back plate, which can be moved against each other.

The body contour is a bit like a horse's hoof.

The back of the body is covered with serrated spines on the sides. In the middle it has a long, spiky tail.

That is why they are also called swordtails.

They have scissors to grab the food and five pairs of legs. These lie under the front body.

The first pair of legs is particularly widened. The genital orifices lie on it.

In addition, like a lid, they cover the subsequent pairs of legs, which carry the gills with which the animals breathe. The last pair of legs is used for locomotion on the sea floor.

On each side of the armor of the front body there is a so-called complex eye, which is made up of several individual eyes. In addition, the two median eyes are located close to each other in the middle of the front body.

Horseshoe crabs grow up to 70 centimeters long and weigh up to five kilograms.

Where do horseshoe crabs live?

Millions of years ago horseshoe crabs were believed to be at home in all the world's seas. Today they can still be found on the Atlantic coast of North America from Maine in the United States to Yucatan in Mexico and in the tropical seas of Southeast Asia.

Horseshoe crabs are pure marine life. They live on the ocean floor. The horseshoe crabs of the North American coast can be found in water up to 50 meters deep.

What species are horseshoe crabs related to?

Despite their name "horseshoe crabs" they are not really crabs at all, but belong to the group of arachnids and there to the order of the swordtails. Their ancestors existed on earth 440 million years ago.

Today there are still five different species of horseshoe crabs, which are divided into three genera. The genera Tachypleus and Carcinoscorpius live in the warm, tropical oceans of Southeast Asia. The genus Limulus lives in temperate water on the North American Atlantic coast.

How old do horseshoe crabs get?

It is not known how old horseshoe crabs can get.


How do horseshoe crabs live?

Horseshoe crabs are living fossils: early relatives of them swam the oceans more than 250 million years ago.

The horseshoe crabs themselves have been around for over 150 million years. They haven't changed much to this day.

Finds of fossilized horseshoe crabs prove this. These were discovered in Solnhofen in Bavaria, for example, and they look almost exactly like their descendants living today.

They were able to survive for such a long time because they are very adaptable and can tolerate different salt contents in seawater as well as different water temperatures.

The primeval sea creatures have a very peculiar way of moving:

They swim with their stomach up in the water. They move their leaf-like widened legs up and down.

So they can move very skillfully and agile through the water. The long tail serves as a drive.

Sometimes they bury themselves in the sand or crawl across the ocean floor.

In doing so, they leave typical three-toed tracks in the sand.

Such traces have also been discovered in fossilized form and were mistakenly mistaken for the footprints of a primeval bird.

Friends and enemies of the Horseshoe Crab

Seabirds and sea turtles in particular hunt horseshoe crabs. But humans are also a threat to them because their habitat is threatened by the pollution of the oceans by humans.

How do horseshoe crabs reproduce?

Horseshoe crabs do not become sexually mature until they are around nine to twelve years old. Although they are marine life, they come ashore in spring to reproduce. Then, by the thousands, they crawl out of the water to the beaches to mate.

This is a rather lengthy procedure: the females sometimes carry the males around on their backs for weeks. The males cling to the female's body with the first pair of hooked legs. Finally, this lays 200 to 1000 eggs, each two to three millimeters in size, in a sand trough. There they are inseminated by the male.

First one centimeter long larvae hatch from the eggs, swim in the open water and dig for food in the sand. The larvae grow into horseshoe crabs and have to shed their skin several times if their shell becomes too small.


What do horseshoe crabs eat?

Horseshoe crabs feed mainly on crabs, worms, mussels and carrion. They find their food by rummaging through the sand on the seabed.