The Atlantic horseshoe crab (Limulus polyphemus) is a marine chelicerate arthropod. Despite its name, it is more closely related to spiders, ticks, and scorpions than to crabs. This species is found in the Gulf of Mexico and along the Atlantic coast of North America. A main area of annual migration is the Delaware Bay, where it plays an important role in the local ecosystem. Find out how the horseshoe crab affects everyone by reading the importance section of this website.