They have claws at the end of each leg. Web-building spiders typically have three claws on the end of each leg. The middle claw and a small tuft of hairs help the spider cling on to its web. The four pairs of legs are powered by muscles. And, muscles attached to the spider's gut and to the inside wall of the cephalothorax can contract to create a strong sucking action during feeding.
Spiders have an open, blood circulatory system.
This sort of blood system has a heart, arteries and veins but no capillaries. The heart is tubular with a single cavity and with valves to maintain the flow of blood always in the same direction. The spider's blood is pale blue due to the presence of haemocyanin dissolved in the lymph. Spiders have lungs. There are two sorts of lungs neither of which is like a human lung.