Silk is produced by many arachnids and has multiple uses, especially for the spiders.

1. Spiders spin silken chambers to cover eggs and for protective retreats.

2. Silk is used for drag lines, which are lines of silk that are anchored to a surface. If a spider is disturbed, it will drop on its drag line and then return when danger is gone. Species of jumping spiders attach a drag line before jumping (maybe in case they miss?).

3. Young spiders, soon after hatching, draw out silken strands that are captured by the wind and transport them to new habitats -- ballooning. (Remember Charlotte's Web)? With the aid of this silk, young spiders become airborne and are carried by the wind. Spiders are often recorded in air samples from heights of up to 16,000 ft.

4. Probably the most important use of silk for many spiders is for capturing prey. Silken webs. I'll bet you thought of this use first. Spider's silk is a fibrous protein which is insoluble in water; as strong as nylon; but has much greater elasticity. Glands within the spider produce silk as a fluid; it moves from the glands to long narrow ducts where it is modified and changed into a solid thread -- the spinnerets on the tip of the abdomen. Spiders build their webs from the outside in and will not run out half way through the process because they have the ability to assess the amount of silk within their glands; smaller amount of silk results in a smaller web. The first webs produced by a spider are perfect; there is no learning is involved. Patterns of webs are characteristic of a particular species of spider. However, individuals of the same species have individual variations to the web pattern within species. Each spider has an individual pattern and the webs of siblings are more similar than those of unrelated spiders. Maybe the offspring imitate the web made by their parents? But wait -- most spiders never see a parent. Females die shortly after she lays eggs.

Regardless of the means of prey capture by spiders, extraoral digestion of the prey occurs. Digestive fluids are pumped into the wounds created by the mouth parts of the spider, mixed with the tissues, and then the mixture is pumped back into the spider.