Even garden spiders can manufacture a repertoire of threads, each with a different purpose. They use five pairs of glands in the abdomen, each of which operates independently of the other. One pair provides the workaday dry thread on which the spider moves round its web, or unravels to shin up and down. Another makes the sticky threads that interlace the web for trapping prey and a third produces the mass of fine filaments that are wrapped about an entrapped insect to secure it until the spider is ready to eat it. Then there is the gland for making the glue that anchors the dry thread, the gland for manufacturing the soft covering for the egg cocoon, and the spinnerets that roll out whatever type of silk is required. Finally, there are the delicate claws on the feet that haul the threads into position on the web, correct tension and feel for the telltale quiver that announces the arrival and entanglement of prey.
Saturday, June 30, 2007
NATURE FIRST - Silken Contradiction
The lightness and apparent fragility of a spider's web is famed. But in fact the material from which it is made is, weight for weight, stronger than steel, more elastic than rubber and tougher than the stuffing of bullet-proof waistcoats. Recent developments in the synthetic production of spider silk have opened new vistas in surgery, space technology, as well as in the manufacture of such things as rip-proof parachutes and tow-ropes.