By Charlotte Owen, WildCall Officer
A spider’s web is made of silk, and while the exact design will vary by species the overall function is the same: a sticky net to trap unsuspecting prey. But not all of the silk strands are actually sticky and a typical web is constructed from several different types of silk. The silk is produced in special ‘spinneret glands’ located at the tip of the spider’s abdomen, and each gland produces a different type of silk that will be used for a particular purpose.
© Alan Price
A spider will start its web with extra-strong ‘structural’ silk to create the basic framework and anchor the web firmly to its surroundings with blobs of a tough, cement-like silk. Then the radial strands are added, like the spokes on a bicycle wheel, and these are spun from a third type of silk that’s extra stretchy so it can withstand the impact of a colliding fly without breaking. When the spokes are complete, the spider weaves a spiral out of the same kind of silk before repeating its spiral with sticky ‘capture’ silk to complete its deadly trap.
A spider can move effortlessly through its own web, diligently testing its threads or racing towards a freshly-caught fly, with no fear of getting stuck thanks to a few clever adaptations. Only the very tips of its legs make contact with the silk and an arrangement of dense, bristly hairs beneath the main claws help to minimise the area that actually comes into contact with the glue, so that even a sticky thread is easily detached.