Spiders belong to the class of arachnids including the scorpions, daddy longlegs, mites, and ticks, and certain other eight-legged land invertebrates. The arachnid body is divided into two parts: anterior and posterior, which is different from insects which divided into three-part body: head, thorax, and abdomen. Insects have three pairs of jointed legs, compound eyes, and two antennae. Unlike insects, arachnids have eight legs, eight eyes in most cases, no wings, and only two parts to their bodies.