Horseshoe crab, Mesolimulus walchi, at the end of its track-way.

Horseshoe crabs are an ancient group of animals, which have hardly changed over the last 450 million years. They are not true crabs but relatives of spiders and scorpions. Horseshoe crabs feed of worms, snails and mussels. They mostly move by walking and burrow themselves in the soft sea-floor. But they are also able to swim with their back towards the sea floor.