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one of the first two extremities on the head of arthropods of the subphylum Chelicerata. Chelicerae, which serve to grind and crush food, are located in front of the mouth. In most animals they consist of three segments and are equipped with chelae. In spiders the chelicerae have a clawlike terminal segment, onto which the duct of the poison gland opens. In parasitic ticks and mites the chelicerae often resemble spiny piercing stylets; they frequently bear cutting lobes and hooks, with which the parasite attaches itself to the body of the host. The homologues of chelicerae in Crustacea, Myriapoda, and Insecta are the upper jaws, or mandibles.