Horseshoe crab necropsy guide v1

The Atlantic, or American horseshoe crab (Limulus polyphemus) has existed largely unchanged for over 100 million years. Millions of individuals spawning along the North American coastline from Maine in the United States to the Yucatan Peninsula, Mexico. Other species can be found in the Indian and Pacific Ocean. The massive deposits of eggs along beaches provide a critical source of food for endangered migrating birds, especially the Red Knot (Calidruis canutus rufa) that feed along the mid-Atlantic Delaware Bay. Horseshoe crabs are also an important component of the sea turtle diet. In addition to their ecological importance, horseshoe crabs are used commercially for bait in eel and conch fisheries and for biomedical purposes in the production of Limulus Amebocyte Lysate (LAL) to detect bacterial toxins in injectable drugs and implantable devices. Commercial demands have led to population declines in some regions. The current International Union for Conservation of Nature (IUCN) listing for L. polyphemus is vulnerable. With growing interest in the health and stability of populations, and potential stressors that can contribute to decline, it is important to have clear and detailed descriptions of horseshoe crab anatomy and necropsy techniques. The purpose of this guide is to illustrate the normal anatomy and the step-by-step technique for dissection of horseshoe crabs.