Their bodies have two major subdivisions, an abdomen and a cephalothorax. These include a pair of chelicerae, a pair of pedipalps, and four pairs of walking legs. Chelicerates lack mandibles and antennae.
Respiration is by means of book gills, book lungs, or tracheae.
Click on the name of a Class to learn more. Animal Diversity . Brusca, R. C., and G. J. Brusca. Sponsored in part by the Interagency Education Research Initiative, the Homeland Foundation and the University of Michigan Museum of Zoology . The ADW Team gratefully acknowledges their support.