Other Free Encyclopedias » Animal Life Resource » Insects and Spiders » Horseshoe Crabs: Merostomata - Physical Characteristics, Habitat, Diet, Behavior And Reproduction, Horseshoe Crabs And People, Horseshoe Crab (limulus Polyphemus): Species Account - GEOGRAPHIC RANGE, CONSERVATION STATUS

Horseshoe Crabs: Merostomata - Horseshoe Crab (limulus Polyphemus): Species Account

accessed august males females

Physical characteristics: The horseshoe crab, also known as American horseshoe crab, is greenish brown to blackish brown. Males are smaller than females. The average body length of males is 14 inches (356 millimeters) and of females is 17 inches (431 millimeters).

Geographic range: The horseshoe crab inhabits the Atlantic and Gulf coasts of North America, from Long Island to the Yucatán peninsula.

Habitat: These crabs live off the coast to depths of more than 200 feet (61 meters).

Horseshoe crabs inhabit coastal regions of eastern North America and the Indo-Pacific. (© John M. Burnley/The National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission.)

Diet: The horseshoe crab eats clams and marine worms.

Behavior and reproduction: Adults live in deeper, offshore waters during the winter, ranging as far out as 25 miles (40 kilometers). In spring they migrate into shallow waters and then onto sandy beaches to spawn. Males approach the beach as the tide rises, followed by the females. Spawning occurs mostly at night near the high-tide line. Females bury as many as twenty thousand eggs in several clutches, or groups, which are fertilized by males. Eggs hatch after thirteen to fifteen days.

Horseshoe crabs and people: In the United States the horseshoe crab is harvested as bait for the conch and eel fisheries. From 1850 until the 1970s the horseshoe crab was processed for fertilizer. Components of its blood and exoskeleton are used for a wide variety of medical purposes.

Conservation status: This species is listed by the World Conservation Union (IUCN) as Near Threatened. It is threatened by too much harvesting and habitat destruction. ∎



Day, Nancy. The Horseshoe Crab. New York: Dillon Press, 1992.

Tanacredi, John T., ed. Limulus in the Limelight: A Species 350 Million Years in the Making and in Peril? New York: Kluwer Academic/Plenum, 2001.


Rudloe, A., and J. Rudloe. "The Changeless Horseshoe Crab." National Geographic Magazine (April 1981) 159, no. 4: 562–572.

Web sites:

"Chitin Research." Sea Grant. http://www.ocean.udel.edu/horseshoecrab/Research/chitin.html (accessed on August 19, 2004).

"Eurypterida: All about Sea Scorpions." Palaeos: The Trace of Life on Earth. http://www.palaeos.com/Invertebrates/Arthropods/Eurypterida/ (accessed on August 19, 2004).

"Eurypterida." Eurypterids.net. http://eurypterids.net/index.html (accessed on August 19, 2004).

"The Horseshoe Crab." Ecological Research and Development Group. http://www.horseshoecrab.org/ (accessed on August 19, 2004).

"The Horseshoe Crab: Putting Science to Work to Help "Man's Best Friend." NOAA Research. http://www.oar.noaa.gov/spotlite/archive/spot_delaware.html (accessed on August 19, 2004).

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