Chelicerate anatomy

thumb|upright=1.2|The jumping spider [[Phidippus audax. The basal parts of the chelicerae are the two iridescent green mouthparts.]] The chelicerae () are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as "jaws", chelicerae may be shaped as either articulated fangs, or as a type of pincers. Some chelicerae, such as those found on nearly all spiders, are hollow and contain (or are connected to) venom glands, used to inject venom into prey or a perceived threat. Both pseudoscorpions and harvestmen —

thumb|right|180px|Arachnid anatomy: (1) four pairs of arthropod leg|legs (2) prosoma (cephalothorax) (3) opisthosoma (abdomen)The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma (cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). It is similar in most respects to an abdomen (and is often referred to as such).