The Class Arachnida IncludsSpiders and scorpions. The class is part of the Phylum Arthropoda, which also includes insects and crustaceans.
Spiders and scorpions are characterized by having four pairs of walking legs; a pair of pincer-like mouthparts called chelicerae; another Pair of frontal appendages called pedipalps, which are sensory inspiders but used for grasping in scorpions; and a body divided into two sections (a combinedhead and thorax called a cephalothorax or prosoma, and an abdomen or opisthosoma.
