How many body sections does a spider have?

A spider has two main body sections: the cephalothorax and the abdomen. In more technical terminology, these regions are also called the prosoma and opisthosoma.

The front section, the cephalothorax, carries the eyes, chelicerae, pedipalps, and four pairs of legs. It is covered on top by a hard plate called the carapace. The rear section, the abdomen, contains major internal organs and bears the spinnerets that produce silk. A narrow flexible connection called the pedicel joins the two sections and allows the abdomen to move independently, which helps a spider position silk while building or repairing a web.

People sometimes count the pedicel as a third section because it looks like a narrow waist, but anatomically it is a connecting structure rather than one of the spider’s two principal body regions. Spiders also have many individual developmental segments internally and evolutionarily, yet these are grouped into two visible tagmata. This two-part body plan helps distinguish spiders and other arachnids from insects, whose bodies are commonly described as head, thorax, and abdomen.