Chelicerata (phylum Arthropoda) A subphylum of arthropods in which the body comprises a cephalothorax or prosoma and an abdomen or opisthosoma, the first pair of feeding structures are the chelicerae that give the subphylum its name, and there are no antennae. The chelicerates are known as fossils from the early Palaeozoic, and originated as marine organisms, but today there are only five marine species: the horseshoe crabs (Merostomata). The subphylum includes the classes Arachnida, Merostomata, and Pycnogonida.

Chelicerata A phylum of invertebrate animals that includes arthropods belonging to the classes Arachnida (spiders and scorpions), Merostomata (horseshoe crabs), and Pycnogonida (sea spiders). The body of these animals is divided into an anterior prosoma and a posterior opisthosoma and bears six pairs of appendages, typically comprising chelicerae, pedipalps, and four pairs of walking legs.

Chelicerata (phylum Arthropoda) Subphylum comprising a diverse group of animals which possess an anterior prosoma (fused head and thorax), a posterior opisthosoma (abdomen), and a pair of jointed pincers. The subphylum includes the spiders, mites, and scorpions, as well as the kingcrab (Limulus) and the eurypterids (Palaeozoic water scorpions).