|MadSci Network: Zoology|
Silk worms are the caterpillars of silk moths, which are in the family Bombycidae. Silk is produced by two modified salivary glands,which are long, complexly-folded tubes that run along the digestive tract, and may be up to seven times the length of the caterpillar itself! The two glands come together in a spinneret organ in the caterpillar's mouth. The hind part of the spinneret has muscles which contract, forcing silk into the tube-like front part of the spinneret. When the tube is touched to something, the silk sticks. The caterpillar then moves its head to draw more silk outward. The silk itself is a double-stranded ribbon, since it comes from two separate glands. It's made of a tough, elastic protein called fibroin.
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