Morphology of Limulus
This article was originally posted at Amazing Zoology . View original article at http://amzoo.in/drl98 Horseshoe crabs live primarily in and around shallow coastal waters on soft sandy or muddy bottoms. They occasionally come onto shore to mate. Horseshoe crabs superficially resemble crustaceans but belong to a separate subphylum of the arthropods, Chelicerata, and are closely related to arachnids. Horseshoe crabs are closely related to the extinct eurypterids (sea scorpions), which include some of the largest arthropods to have ever existed, and the two may be sister groups. The earliest horseshoe crab fossils are found in strata from the late Ordovician period, roughly 450 million years ago. Morphology of a limulus (horseshoe crab) : marine arthopod which lives near the shore. Frontal organ : organ of the horseshoe crab situated at face-level. Chelicera : a pair of venomous hooks situated on the head of a horseshoe crab. Walking leg : floating appendage. Genital operculum : struc...