During the spawning season, adults typically inhabit bay areas adjacent to spawning beaches and feed on bivalves. In the fall, adults may remain in bay areas or migrate into the Atlantic Ocean to overwinter on the continental shelf. (Natural History Web site: (http://www.horseshoecrab.org/nh/habitat.html) There are many species that depend on the horseshoe crab for food and habitat and the interactions between all such species determine the health and wealth of the ecosystem, associated with the Horseshoe crab. Shorebirds, of many kinds are dependant upon the Horseshoe Crab larvae for food.

At least 11 species of migratory birds use horseshoe crab eggs as their primary food supply during their 2 to 3-week stopover. The eggs replenish their fat supply during their trip from South American wintering areas to Arctic breeding grounds. Most of the eggs consumed are from nests that have been disrupted by waves and storms, so the feeding of the shorebirds does not have an adverse affect on the breeding success of the horseshoe. (Natural History Web site: (http://www.horseshoecrab.org/nh/eco.html)

Additionally, many other interactions occur between species in the shared ecosystem including Finfish and Sea turtles, who also rely on the larvae for essential nutrients.

As a crab ages and its growth rate slows, it sheds less frequently and begins to display a striking variety of hitchhikers. An abundance of smaller creatures live on (and off) the horseshoe crab in a symbiotic...

Sponges and other fouling Porifera occasionally become established on the posterior of horseshoe crabs; probably when the water is cool and the crab is half buried in a dormant stage. The Limulus leech (Bdelloura) is a flatworm that is found around the book gills and leg joints of crabs, especially on older females that have not shed for a long time. The leech lays its eggs in the "pages" of the crab's book gills and these are visible as little dark spots. It may also use the cuticle of the gills as a substrate for chemical activity. Several crustaceans are regular companions of the horseshoe crab, including mud crabs and sand shrimp. Tiny juvenile spider and rock crabs also find a home in the crevices inside Limulus molts. The mollusks are better represented on the horseshoe than any other phylum. Several species of bivalves become attached to the crabs, and a number of snails are also regularly found on them. Mussels usually attach themselves near the hinge where water is circulated to the gills by the resting crab. Three species of slipper shell -- the common, convex and flat-- are regularly found attached to the underside of the crab. (Natural History Web site: (http://www.horseshoecrab.org/nh/eco.html)
Works Cited

Sturtevant, Patty Ph.D. "THE HORSESHOE CRAB http://www.marinelab.sarasota.fl.us/WHORSESH.htm

Natural History Website at http://www.horseshoecrab.org/nh/eco.html

Natural History Website at http://www.horseshoecrab.org/nh/habitat.html