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Atlantic Horseshoe Crabs
Size: 14 -19 in (36 - 48 cm)
Weight: 11 lbs (4.8 kg)
Diet: Omnivorous
Scientific Name: Limulus polyphemus
Geographical Range: North American coast of the Atlantic Ocean
Horseshoe Crabs are primitive arthropods that have been around for around 350 million years old, which means they have been around for longer than the dinosaurs. They look and are called crabs but they are actually more related to spiders and scorpions. Even though they look quite intimidating they are actually harmless to humans.
The North American Horseshoe Crabs, also known as the Atlantic Horseshoe Craps, are found on the North American coast of the Atlantic Ocean. The Eggs of these animals are laid on the beach, once they hatch the juveniles live on the ocean floor of tidal flats. Once they reach adulthood they make their way deeper into the ocean. Then they return to spawn. Their eggs are a special part of many animals’ diets.
They are nocturnal hunters and feed on worms, clams, and algae. They pick up food with appendages near the mouth. They will crush their food with their strong legs and then they will eat it.
They are one of four extant species of Horseshoe craps. These include Carcinoscorpius rotundicauda, Tachypleus gigus, and Tachupleus tridentatus. These species are found in the Indian Ocean and on the Asian coasts of the Atlantic.
The American Horseshoe Crab is threatened by habitat loss and overharvesting. They are harvested for bait and they are caught for medical purposes. They are listed as vulnerable.
There are three parts of the Horseshoe Crabs body. The prosoma, opisthosoma, and the telson.
The prosoma, or head, is where the crab gets its name, the hard exoskeleton shell is in the shape of a horse's shoe. It contains most of the organs in its body like the heart, brain, mouth, glands, and most of the nervous system. It also protects the largest set of eyes on the body. Horseshoe Crabs have 9 eyes scattered around their body. They also have several light receptors which are dispersed on the back of the animal body. These are to sense movement and moonlight changes.
The opisthosoma, or middle section, looks like a spiny triangle. There is a ridge in the center and spines on the sides. The spins are able to move to protect the Horseshoe Crab. The underside has the gills of the animal and muscles to move around in the water.
The Telson, or the tail, is used to flip the animal over if it happens to be upside down.
“Atlantic Horseshoe Crab (Limulus Polyphemus): U.S. Fish & Wildlife Service.” FWS.gov, https://www.fws.gov/species/atlantic-horseshoe-crab-limulus-polyphemus.
“Horseshoe Crab.” Chesapeake Bay Program, https://www.chesapeakebay.net/S=0/fieldguide/critter/horseshoe_crab.
“Horseshoe Crab.” National Wildlife Federation, https://www.nwf.org/Educational-Resources/Wildlife-Guide/Invertebrates/Horseshoe-Crab.
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