A tarantula is an invertebrate and so has an exoskeleton. A tarantula’s body consists of two main parts, the prosoma or the cephalothorax (the former is most often used because there is no analogous "head") and the abdomen or opisthosoma. The cephalothorax and opisthosoma are connected by the pedicle or what is often called the pregenital somite. This waist-like connecting piece is actually part of the prosoma and allows the opisthosoma to move in a wide range of motion relative to that of the cephalothorax.

The prosoma is the forward main body part. The eight legs, the two chelicerae with their hollow fangs, and the pedipalps are attached to the prosoma. The chelicerae are two single segment appendages that are located just below the eyes and directly forward of the mouth. The chelicerae contain the venom glands that vent through the fangs. The fangs are hollow extensions of the chelicerae that inject venom into prey or animals that the tarantula bites in defense, and they are also used to masticate (chew). These fangs are articulated so that they can extend downward and outward in preparation to bite or can fold back toward the chelicerae as a pocket knife blade folds back into its handle.