Spiderwebs are an intricate fabrication of proteinaceous spider silk extruded from a spider's spinnerets.  Spiderwebs are incredibly strong and are quantitatively five times stronger by weight than steel of the same diameter.

Some people suffer from what is called arachnophobia, which is a morbid fear of spiders.

Formation of spiderwebs

Spiders have several spinneret glands located at their abdomen, which produce the silken thread. Each gland produces a thread for a special purpose. Seven different gland types have currently been identified, although each species of spider possesses only a few of these types, never all seven at once.

Normally a spider has three pairs of spinnerets, but there are spiders with just one pair or as many as four pairs of spinnerets, with each spinneret having its own function.

During the process of making a web, the spider will use its own body for measurements, a very practical and ergonomic design feature of any web. This will allow the spider to move quickly around its own web with very few faults.

It will start with the most difficult part of construction, the first thread. The spider effectively uses the wind to carry its initial adhesive thread. With some luck, the silk is released from its spinners and carried by the wind to a suitable adherable surface. When it sticks to a surface, the spider will carefully walk over the thread and strengthen it with a second thread. This process is repeated until the primary thread is strong enough to support the rest of the netting.

After strengthening the first thread, the spider will continue to make a Y-shaped netting. The first three radials of the web are now constructed. More radials are added, making sure that the distance between each radial is small enough to cross. This means that the number of radials in a web directly depends on the size of the spider plus the size of the web.

After the radials are complete, the spider will fortify the center of the web with about five circular threads. Then a spiral of non-sticky, evenly spaced, circular threads are made for the spider to easily move around its own web during construction. The spider then, beginning from the outside in, will methodically create the adhesive spiral threads. It will utilize the initial radiating lines as well as the non-sticky spirals as guide lines. The spaces between each spiral will be directly proportional to the distance from the tip of its back legs to its spinners. This is one way the spider will use its own body as a measuring/spacing device. While the sticky spirals are formed, the non-adhesive spirals are removed as there is no need for them anymore.

After the spider has completed its web, it will chew off the initial three center spiral threads then sit and wait. If the web is broken without any structural damage during the construction, the spider does not make any initial attempts to rectify the problem.

Webs allow a spider to catch prey without having to expend energy by running it down. Thus it is an efficient method of gathering food. However, constructing the web is in itself an energetically costly process due to the large amount of protein required, in the form of silk. In addition, after a time the silk will lose its stickiness and thus become inefficient at capturing prey. It is not uncommon for spiders to eat their own web daily to recoup some of the energy used in spinning. The silk proteins are thus recycled.

The tensile strength of spider silk is greater than the same weight of steel and has much greater elasticity. Its microstructure is under investigation for potential applications in industry, including bullet-proof vests and artificial tendons. Researchers have used genetically modified mammals to produce the proteins needed to make this material.

Communal spiderwebs

Occasionally, a group of spiders may build webs together in the same area. One such web, reported in 2007 at Lake Tawakoni State Park in Texas, measured 200 yards (180 m) across. Entomologists believe it may be the result of social cobweb spiders or of spiders building webs to spread out from one another.

There is no consensus on how common this occurrence is.

Outside influences

Certain drugs, including caffeine, affect the way spiders build webs.

Administering certain drugs to spiders has an effect on the structure of the webs they build. It has been proposed by some that this could be used as a method of documenting and measuring the toxicity or the effects on motor co-ordination of various substances.

Low gravity

It has been observed that being in Earth's orbit has an effect on the structure of spider webs in space.

Spider webs were spun in low earth orbit in 1973 aboard Skylab, involving two female European garden spiders (cross spiders) called Arabella and Anita, as part of an experiment on the Skylab 3 mission. The aim of the experiment was to test whether the two spiders would spin webs in space, and, if so, whether these webs would be the same as those that spiders produced on Earth. The experiment was a student project of Judy Miles of Lexington, Massachusetts.

After the launch on July 28, 1973, and entering Skylab, the spiders were released by astronaut Owen Garriott into a box that resembled a window frame. The spiders proceeded to construct their web while a camera took photographs and examined the spiders' behavior in a zero-gravity environment. Both spiders took a long time to adapt to their weightless existence. However, after a day, Arabella spun the first web in the experimental cage, although it was initially incomplete.
The first web spun by Arabella

The web was completed the following day. The crew members were prompted to expand the initial protocol. They fed and watered the spiders, giving them filet mignon. The first web was removed on August 13 to allow the spider to construct a second web. At first, the spider failed to construct a new web, but, supplied with additional water, a second web was built, this time more elaborate than the first. Both spiders died during the mission, possibly due to dehydration.

When scientists were given the opportunity to study the webs, they discovered that the space webs were finer than normal Earth webs, and although the patterns of the web were not totally dissimilar, variations were spotted, and there was a definite difference in the characteristics of the web. Additionally, while the webs were finer overall, the space web had variations in thickness in places: some places were slightly thinner, and others slightly thicker. This was unusual, because Earth webs have been observed to have uniform thickness.