The horseshoe crab, Limulus polyphemus currently plays important ecological, medical and commercial roles. Ecologically, this species is vitally important to a variety of migratory birds. Limulus come ashore to breed in the early spring when several species of migratory birds are heading north to their summer breeding grounds. Over ten bird species that are long distance migrants, and thus are of interest to a huge number of of birdwatchers and scientists, stop over to feed on their eggs. These species interrupt their long migrations to the arctic each year in the area of Cape May, N.J. to gorge on the >500 tone of eggs laid by the breeding Limulus (Castro and Myers, 1993). The high fat and protein content are crucial in order for these birds to be able to arrive at their breeding grounds ready to lay eggs and survive until is available (Clark et al., 1993). Limulus also have important impacts on the environment in which they live. They greatly affect the benthic community of the seafloor when they plow through the substratum while feeding on bivalve molluscs and polychaete worms (Shuster, 1982) to a depth of 18 cm (Kraeuter and Fegley, 1994). In addition, numerous species of marine fisheries and marine turtles feed on either the eggs, larvae or adult stages (Shuster, 1982), including the endangered loggerhead turtle (Tanacredi, 2001).

Limulus have also been important parts of commercial catches over the past several hundred years and have been used historically as fertilizer (Shuster, 1982) and bait; over 2 million were harvested for use as eel and conch bait in 2000 alone (Sargent, 2002). Biomedical firms also make use of large numbers of horseshoe crabs. The blood of Limulus is used as a very sensitive, and FDA required (Berkson and Shuster, 1999), assay for the presence of gram-negative bacteria and their toxins in products such as dialyzers, antibiotics, and intravenous solutions (Widener, 1999). The switch from a rabbit-based test to this Limulus Amoebacyte Lysate test has turned this aspect of Limulus harvesting into a 250 million dollar industry (Sargent, 2002). Fortunately for Limulus stocks, these companies "only" remove approximately 1/3rd of the blood and this is reported to lead to a 90% survival rate (Rudloe, 1983). Unfortunately, the bled animals are at times returned to sites hundred of km from their site of collection, suffer increased mortality because of long distance trucking, or are not returned to the ocean at all (Sargent, 2002).