Spiders and their strange webs
Why don’t spiders stick to their webs?
A spider’s web is one of the strongest and stickiest substances known to man (relatively speaking, it is stronger even than steel). A single spider can spin an intricate web in less than an hour after which, she (yes, we refer to spiders as “she” – ask the boys – they’ll explain why) waits around for bugs and other critters to get stuck in the web so she can devour them. The spider feeds the webbing out of their abdomen and they use a few of their legs to guide the web into place while the other legs are used for pulling far reaching webs into place, feeling for the correct position to attach a web, picking their nose, and of course, to walk across the web.
The opening that the spider web comes out of is called a spinneret. Most spiders have three pairs of spinnerets but some have just one pair and others have up to four pairs. Each spinneret produces a different kind of web. Some web material is used for trail lines that the spider uses to lower themselves from high places while others are used for building spider webs to trap prey. One type of very thin spider web is used as a signal line. When something brushes against it, the spider feels the vibration and uses it as a signal that prey (or danger) is near.
A spider begins the web building process by spinning a single, light line. The wind catches this single strand and eventually sticks it to something nearby. The spider quickly scampers across the newly attached line and adds additional layers to strengthen it. Then the spider builds two lines going down and attaches these for form a Y shape. Then circular webs are build around the Y-shaped foundation.
But why don’t spiders get stuck in their own web? After much work with the creepy crawly critters, researchers at the Smithsonian Tropical Research Institute found that spiders do not stick to their own webs for two reasons. Firstly, they have legs covered by hair. If the spider’s leg touches the web against the grain of the hairs then they stick to the web more. Conversely, if the spider’s leg touches the web with the grain then the web slides off more easily. Spiders use this to their advantage by moving across the web in a precise direction so they will not stick to it.
But, there is a second reason the web slides off more easily – spider’s legs have a non-stick chemical coating. The scientists proved this by coating the spider’s leg hair with hexane and water and watched as they stuck to the web. To their dismay, the hairy spider legs groomed with spider hair gel did not make the spiders any less ugly (although one spider supposedly began walking with an exaggerated gate and snapping his fingers).
What is the difference in a spider web and a cobweb?
A cobweb is simply a spider web that is no longer used by the spider.