Learn about horseshoe crabs, ancient arthropods that are related to spiders and have survived for over 500 million years. Find out their classification, distribution, appearance, diet, predators, and more. American horseshoe crab (Limulus polyphemus): Found along the eastern coast of the USA and in the Gulf of Mexico. Tri-spine horseshoe crab (Tachypleus Tridentatus): Found in the Indo-Pacific region. Horseshoe crab is the common name for various marine chelicerate arthropods of the family Limulidae, and in particular the extant species Limulus polyphemus of the Atlantic of North America. The other extant species known as horseshoe crabs are the Indo-Pacific species Tachypleus gigas, Tachypleus tridentatus, and Carcinoscorpius rotundicauda. Horseshoe crabs are characterized by a heavy, domed, horseshoe-shaped carapace, a pointed, spiky telson ("tail"), a jawless mouth, and the presence of ... Learn about horseshoe crabs, living fossils that have survived for over 450 million years. Discover their anatomy, lifecycle, distribution, and why their blood is valuable for humans.
