What are spider webs made of? And how do they spin them?

Spiders have structures called spinnerets on their abdomen, usually on the underside to the rear. These are the silk-spinning organs. Different species have different numbers of spinnerets, but most have a cluster.

At the end of each spinneret is a collection of spigots, nozzle-like structures. A single silk thread comes out of each.

Jan explains, 'Although it looks a bit like an icing nozzle, the silk is pulled out by gravity or the spider's hind leg. The silk is liquid when it's inside the spider.'

Before it is extruded out of the spinneret, cribellate silk first passes through a sieve-like structure called the cribellum. Spiders that make this type of silk also have a row of specialised leg bristles called the calamistrum, which combs the silk out and gives it the different, woolly texture.

Spiders then follow various patterns of activity to construct their webs, depending on what species it is. It's fascinating to watch.

Do all spiders make webs?

Although webs are the most well-known use for spider silk, not all spiders make webs to catch their prey. In fact, less than half of the 37 spider families in Britain do.

Other spiders, such as crab spiders in the family Thomisidae, are 'sit and wait' predators - for example Misumena vatia lurks on flower heads, waiting to ambushing visiting insects. Others, such as jumping spiders in the family Saltidae, actively follow their prey and catch it by leaping on it.

However, even spiders that don't make webs have uses for silk, including creating moulting platforms, sperm webs for males, and retreats.

Jan adds, 'Jumping spiders, for example, make little silken cells in which to hide in during the day - a bit like a sleeping bag.'

Most spiders use silk to wrap their eggs.

Another common use for silk is as a drag line. Every so often a spider attaches a thread of silk to something, like an anchor, so that if it falls, it won't fall too far and can drag itself back up to the previous position.

Ballooning is another spectacular use for silk, allowing the mass dispersal of spiderlings and small adults.

After climbing to a relatively high point, the spider points its abdomen skywards and pulls out one to several threads. When air or electrostatic currents carry the threads upwards, the spider follows. They can be carried many thousands of metres.