Limulus polyphemus (Atlantic horseshoe crab) (Sanibel Island, Florida, USA) 6
Limulus polyphemus (Linnaeus, 1758) - Atlantic horseshoe crab in Florida, USA. (December 2012)
This is the only living species of Limulus. Several fossil species have been reported from the Mesozoic and Cenozoic. Limulus horseshoe crabs are not true crabs, which are decapod crustaceans. Horseshoe crabs are xiphosuran chelicerates. The exoskeleton is tripartite, consisting of a semicircular cephalon (head), also called the prosoma, a subtriangular opisthosoma that is bordered by a series of spines, and a large posterior spine called a telson.
Classification: Animalia, Arthropoda, Chelicerata, Merostomata, Xiphosura, Limulidae
Locality: Algiers Beach, southern margin of Sanibel Island, southwestern Florida, USA