Merostomata - Horseshoe Crabs

There are four living species in this class. The horseshoe crabs you see today are little changed from the horseshoe crabs you might have seen 250 million years ago.

Horseshoe crabs have three body segments, the prosoma, the opisthosoma, and the telson . The prosoma is the horseshoe-shaped front part of the horseshoe crab's body. The horseshoe crab has ten eyes on the top of the prosoma and six pairs of appendages on the underside of the prosoma.

Five pairs of appendages are for walking and one pair of chelicera help the horseshoe crab move food into its mouth. The opisthosoma or abdomen connects to the prosoma with a hinge. The telson or tail is attached to the opisthosoma. Some people think that the telson is a stinger, but it is not. The horseshoe crab uses the telson to steer itself and to flip itself over if it gets turned on its back!

World Status Key
Least Concern Near Threatened Vulnerable Endangered Critically Endangered Extinct in Wild Extinct
Status and range is taken from ICUN Redlist. If no status is listed, there is not enough data to establish status.

US Status Key
Threatened in US Threatened in NH Endangered in US Endangered in NH Introduced
Status taken from US Fish and Wildlife and NH Fish and Game

Location Key
Africa Asia Australia/Oceania Europe North America South America NH Click for More Info Click for Image

New Hampshire Species		North/Central American Species
Horseshoe Crab - Limulus polyphemus

Other Species Around the World
Mangrove Horseshoe Crab - Carcinoscorpius rotundicauda Horseshoe Crab - Tachypleus gigas		Tri-spine Horseshoe Crab - Tachypleus tridentatus
Additional Information   Key: Profile Photos Video Audio Horseshoe Crab - Limulus polyphemus Limulus polyphemus is found from Nova Scotia in Canada south to the Yucatan in Mexico. Source: Arkive Intended Audience: General Reading Level: Middle School Horseshoe Crab - Limulus polyphemus Limulus polyphemus feeds at night on worms, small molluscs, and algae. Source: Animal Diversity Web Intended Audience: General Reading Level: Middle School