If you look around the area where you live, you may notice many different kinds of spiders.The world has anywhere from 40,000 to 120,000 different species of spiders. In any ordinary field, two million spiders may be hard at work.They thrive in the hottest jungles and the coldest polar regions. They have been found even at the height of 22,000 feet (6,700 meters), on Mount Everest! The spider’s incredible silk-spinning organs are on its abdomen. The silk thread begins as a liquid that hardens on contact with the air. A spider can make many different kinds of silk thread. Each kind has its own special purpose. By using certain tubes, or by combining the threads in different ways, a spider can make a very delicate thread or a thick, broad band of silk. Some sizes are used to line their nests or retreats. Others are used for egg cocoons, or for tying up victims, or for weaving webs. Spider silk is stronger than silkworm silk. If twisted into a rope.it can lift more weight than a rope of the same size made of iron wire! In his book Sociobiology, E.O. Wilson quotes an old Ethiopian proverb, “When spider webs unite, they can halt a lion.” Although lions have never been seen in spider webs, there does seem to be some truth in this. Scientists believe that cooperative prey-capturing in spiders has probably evolved because it improves efficiency. It also allows the spiders to go after larger prey. Cooperation and sharing improve the use of their webs and the food available to them.