Atlantic horseshoe crab

Description

The Atlantic horseshoe crab (Limulus polyphemus), also known as the American horseshoe crab, is a species of marine and brackish chelicerate arthropod. Despite their name, horseshoe crabs are more closely related to spiders, ticks, and scorpions than to crabs. It is found in the Gulf of Mexico and along the Atlantic coast of North America. The main area of annual migration is Delaware Bay along the South Jersey Delaware Bayshore. Their eggs were eaten by Native Americans, but today Atlantic horseshoe crabs are caught for use as fishing bait, in biomedicine (especially for Limulus amebocyte lysate) and science. They play a major role in the local ecosystems, with their eggs providing an important food source for shorebirds, and the juveniles and adults being eaten by sea turtles. The other three extant (living) species in the family Limulidae are also called horseshoe crabs, but they are restricted to Asia. The Atlantic horseshoe crab is the only extant (living) species of horseshoe crab native to the Americas, although there are other extinct species only known from fossil remains from this region. The other living species of horseshoe crab are restricted to Asia, but all are quite similar in form and behavior. The Asian species are Tachypleus tridentatus, Tachypleus gigas and Carcinoscorpius rotundicauda. Atlantic horseshoe crabs are found along the Atlantic East Coast of the United States, ranging from Maine to Florida. In the Gulf Coast of the United States, they are found in Florida, Alabama, Mississippi and Louisiana. Outside the United States, the only breeding population is in Mexico's Yucatán Peninsula, where it is found on western, northern and eastern coasts. Individuals rarely appear outside the breeding range, with a few records from the Atlantic coast of Canada (Lahave Island on Nova Scotia), the Bahamas, the Turks and Caicos, Cuba and the western Gulf of Mexico (Texas and Veracruz). Historic claims of horseshoe crabs on Jamaica and Hispaniola (in the Dominican Republic) have not resulted in any discoveries after expeditions there. There have been attempts of introducing it to Texas, California and the southern North Sea, but these all failed to become established. Records from Europe, Israel and Western Africa are considered releases/escapees of captives. Atlantic horseshoe crabs range from shallow coastal habitats such as lagoons, estuaries and mangrove to depths of more than 200 m (660 ft) up to 56 km (35 mi) offshore.