The class Merostomata includes two different groups of marine organisms, the eurypterids and the horseshoe crabs. However, eurypterids are now extinct being that they once lived 200 to 500 million years ago. They feed on small invertebrates. Members of this class have a large shield that covers the cephalothorax, and the compound eyes are reduced.
horseshoe crabs
Horseshoe crabs live mostly partly buried in the mud of the sea floor where they hunt for small animals, worms, crustaceans and even fish which they eat. As well as pushing through the mud they can walk on their legs and even swim. A distinct part of a Horseshoe crab is the long stiff caudal spine. This serves only to help the animal in moving forward and to right it if it gets turned on its back, which is an important function as none of its limbs reach beyond the edge of the carapace. Shorebirds primarily feed on horseshoe crab eggs exposed on the surface, but sufficient surface eggs are available only if horseshoe crabs are spawning at high densities. Therefore, adequate spawning densities must be maintained to ensure availability of horseshoe crab eggs for shorebirds.
Scientific name: Merostomata
Higher classification: Chelicerata
Rank: Class
Scientific name: Merostomata
Higher classification: Chelicerata
Rank: Class