Why don't spiders get caught in their own web?

29 September 2015

Question

Hi  I'm Victoria Lakota and I am eight years old. Why does the spider doesn't get hang up on It's spider web?        

THANK YOU.

Answer

We put Victoria's question to zoologist Max Gray...

Max - The answer is that they get caught a bit, but they're very good at getting out of it essentially.

Kat - What is it in a spider's web then that's making it sticky? Tell us about the spider web.

Max - So, the web itself, the strand of silk that the spider creates to make its web out of is coated in a sort of sticky adhesive, "goo" let's call it. I'm not sure exactly what it's made up of. But it's kind of a thick liquid that sticks to the silk and that's what makes it sticky. The spider itself is very well adapted to avoid getting stuck in its own glue. But the interesting thing about this one, I went to research this question is that, it's only been figured out relatively recently. The paper that this was based on was only published in 2012. So, we didn't really know for quite a long time.

Kat - So, up until then, people just assume that spiders have these like magic non-stick feet.

Max - Probably. The assumption was that their feet are covered in some sort of anti-adhesive oil or something that neutralise the glue. That's only one of three separate things that spiders use to avoid getting stuck in their own webs. The second of which is they have a really clever structure on all of their legs. They're covered in tiny, tiny little hairs which has a dual effect of firstly just reducing the surface area that ever actually touches the web in the first place. So, there's less to stick to on a spider's leg than say, on a fly's leg. But also, they're very, very thin and all these tiny little hairs come to a very fine point. And so, when the glue does get stuck to them, the oil that those hairs is coated in causes it all to run down to the tip and then it just drops off, rather than sticking to that hair at all in the first place. Chris - So, why haven't the insects evolved the same trick?

Max - They don't spend as much time in a web.

Chris - I suppose it's a once in a lifetime experience.

Max - How many insects manage to escape the web to reproduce and contribute their genes to the next generation?

Kat - Spiders that haven't figured that one out aren't really going to do very well in the long term.

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