Each leg has 7 segments. In most kinds of spiders, the tip of the last segment has 2 or 3 claws. A pad of hairs called a scopula may surround the claws. The scopula sticks to smooth surfaces and helps the spider walk on ceilings and walls. Each leg is also covered with sensitive bristiles that serve as organs of touch and perhaps organs of smell.
Some bristles pick up vibrations from the ground or air, or the spider's leg.
Others detect chemicals in the environment. When a spider walks, the first and third leg on one side of its body move with the second and forth leg on the other side. Muscles in the legs make the legs bend at the joints. But spiders have no muscles to extend their legs. The pressure of the blood in their bodies makes their legs extend.