Spiders and SilkBy Jill Moss
This is the VOA Special English SCIENCE REPORT.
Spiders are very small. So it is easy to think that they do not make anything strong. However, a scientist at Oxford University in Britain has discovered this it not true. David Knight says that eight-legged spiders create a material called silk that could be as strong as rope.
Mr. Knight has been studying spiders and the natural silk material they produce for many years. The main subject of his research is the complex chemical process that spiders use to make their silk. Mr. Knight's findings were published recently in the British magazine, Nature.
Mr. Knight says that silk is very thin. But it is extremely strong. This is because the threads of silk are made into a complex structure. Mr. Knight says the silk is made from protein molecules. It forms in the parts of the spider's body called silk glands. The silk is like pieces of string. It is rolled into small balls.
When the spider wants to make, or spin, some silk, it carefully unrolls the balls. The pieces of string join together. When the spider wants to move, it joins all the small strings of silk into one long thread. Then it can move down the thread. Wherever a spider goes, it spins a silk thread behind itself.
Mr. Knight says that spiders can make and use as many as seven kinds of silk. It uses one kind of silk for making the structure of the spider's web -- where it traps insects. It uses another stretchy silk for making round links in the web. Mr. Knight says those links are covered by another kind of silk that is very sticky. This sticky material makes it difficult for insects to escape after they are caught in the spider's web.
Spider silk is strong enough to catch insects. Its strength can be measured. Mr. Knight says the silk from an Orb web spider is five times stronger than fiber made by man. He also estimates that a rope of spider silk as thick as one pencil could pull a large ship through the water. He says one day people may be able to make material as strong as a spider's silk. It could be used in place of rope.
Spider silk is a useful material. It does not harm the environment. It can be re-used by spiders. So people may wonder why they cannot use spiders to manufacture silk for industrial use. Mr. Knight says it is because spiders can not be farmed. He says if you put them in a room together, they will try to eat each other.
This VOA Special English Science Report was written by Jill Moss.