American Horseshoe Crab, Limulus polyphemus

American Horseshoe Crab, Limulus polyphemus. Crab collected off Tigertail Beach, Marco Island, Florida, January 2019.  Length:  41 cm (16 inches). A catch, photograph and release.

General information: The Atlantic Horseshoe Crab, Limulus polyphemus, is a one of four members of the Limuldilae Family of horseshoe crabs that are also known as Helmet Crabs. They are not actually a true crab, being more closely related to arachnids, the spiders and scorpions. The Atlantic Horseshoe crab sports a primitive look resembling something closer to an alien than animal. That’s because its characteristics have remained unchanged for 350 million years, giving us a glimpse into what life looked like during the prehistoric era.

Identification:  Horseshoe crabs get their name from their unusual shape resembling something close to a horse shoe, their bodies have three parts, the head, body and tail which looks like it may have the same offensive capabilities of a stingray, however the tail or telson of horseshoe crabs is purely so they can flip themselves back over if they get tossed around in the surf. Horseshoe crabs are a brownish, olive green color. Females are typically larger than the males, weighing up to 5.0 kg(11.0 lbs), and are 30 cm (12 inches) in width and 60 cm (2 feet 0 inches) in length.  The largest horseshoe crabs have been caught off the coast of Georgia.

Diet :  The American Horseshoe Crab is a scavenger during its juvenile life stage consuming algae and other organic matter.  With maturity their diet changes to slightly larger prey and includes other crustaceans, and worms. They lack teeth and mandibles and all of the food they capture must be crushed by their legs prior to consumption.

Habitat and Range:  The American Horseshoe Crabs are oceanic marine creatures. Their habitat switches as they go through their life stages:  eggs, larvae and juveniles are found within coastal and intertidal zones while the adults are found farther off coast in waters over sandy or muddy bottoms. The American Horseshoe Crab is found primarily along the eastern coast of the United States from from Maine to Alabama. They have are also known residents of the Yucatán Peninsula of Mexico.

Conservation Status: Horseshoe crabs are important contributors to the marine ecosystems.  Their millions of eggs provide food for other terrestrial and marine life. Their body structure providing habitat for a multitude of species. From a conservation perspective the American Horseshoe Crab is currently considered as VULNERABLE.

Synonyms:  Limulus albus, Limulus americanus, Limulus cyclops, Limulus occidentalis, Limulus sowerbii, and Monoculus polyphemus.