Contrary to popular opinion, spiders are not insects at all. Insects, which belong to the class Insecta, have six legs, three body segments, and typically possess wings at some stage of development. Spiders, however, are Arachnids, having eight legs, two body segments, and no wings.

On the spider abdomen, several silk glands hold viscous liquids that pass through minute tubes called spinnerets; normally a spider has three pairs. Upon being drawn from a droplet, the liquid protein structurally rearranges to polymerize into solid silk threads. Interestingly, once the protein leaves the gland, its molecular mass increases from 30.000 Dalton to about 300.000 Dalton to become a silk fiber. The catalyst involved in this transformation remains a mystery. The silken threads are incredibly fine -- about 1/10,000 of an inch in diameter, 30 times smaller than the diameter of human hair -- yet it is strong enough to stop a bee in full flight. Although spider silk is stronger than steel, the web can absorb energy that causes it to stretch, up to 140 percent of its length, without bouncing back. Even at low temperatures, the gossamer strands maintain their amazing structural properties.

Many spiders are recyclers, eating the broken protein-rich strands of their webs in order to spin new silk for repairs. Spiders' silk is not decomposed by fungi or bacteria like other proteins, and it contains hygroscopic (water-binding) substances that prevent threads from drying out; additionally, it is coated with acids. Ancient Greeks applied spider webs to wounds in order to promote healing, and it has since been discovered that spider silk is covered with antiseptic agents. The spider web is an intricate device designed to trap bugs, and its fabulous properties make it a wonder of materials science.