Why do spiders sometimes stay still for a long time?

It's our belief at BBC Science Focus that spiders don't move often purely to increase their creep factor. 

22nd July 2009
Why do spiders sometimes stay still for a long time? (iStock)

Asked by: Dan McLaughlin, Pudsey

Web-spinning spiders obviously remain motionless while they are waiting for something to land in their web. Moving around wastes energy and draws attention to the spider, which makes it more likely to be eaten by birds, and makes flies less likely to get caught in the web.

Spinning a web is quite an energy-intensive process and a spider may have to wait days or weeks for a catch, so it is important to conserve as much energy as possible. Hunting spiders are much more active, but many of them are nocturnal predators and spend the day tucked away in a nest or under a rock - again, this is to conserve energy and avoid becoming prey.

The giant house spider (Tegenaria duellica) - the one you normally find in the bathtub - is actually a web spinner and most of the time it stays inside its messy, funnel-shaped web in the attic or behind those boxes in the garage. The ones you find roaming around the house are usually males looking for a mate in late summer and early autumn. They are easily startled and will tend to freeze if the light gets switched on suddenly. But they're the fastest runners of all the true spiders and can reach speeds of 0.53m/s when they want to.

 


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