Merostomata

views updated May 14 2018

Merostomata (phylum Arthropoda, subphylum Crustacea) Class that includes the horseshoe crabs (king crabs) and the extinct eurypterids. The eurypterids (‘water scorpions’), which grew up to 3 m long, ranged from the Ordovician to the end of the Palaeozoic; the horseshoe crabs also appeared in the Lower Palaeozoic and have survived to the present.

Merostomata

views updated May 08 2018

Merostomata (phylum Arthropoda) Class which includes the king crabs (horse-shoe crabs) and the extinct eurypterids or ‘water scorpions’. Eurypterids were usually 10–20 cm in length, but some were much larger, e.g. Pterygotus which grew up to 2 m long. They ranged from the Ordovician to the end of the Palaeozoic. The horseshoe crabs also appeared in the Lower Palaeozoic and have survived to the present.

horseshoe crab

views updated May 23 2018

horse·shoe crab • n. a large marine arthropod (class Merostomata) with a domed horseshoe-shaped shell, a long tail-spine, and ten legs, little changed since the Devonian period.

horseshoe crab

views updated Jun 27 2018

horseshoe crab See MEROSTOMATA.

Merostomata

views updated May 09 2018

Merostomata See Chelicerata.