By Jonas Wolff
Why do spiders have hairy legs? – Audrey, age 5, Fitzroy, Melbourne.
Good question, Audrey! Believe it or not, I have studied the hairy legs of spiders for years and can give you some definitive answers on this.
But before we talk about the spider’s fur, think about your very own hairs.
Why do we have hair?
First, there is the hair on your head, which protects you from the sun and rain. Then, there is smaller hair above your eyes – your eyebrows and eye lashes. These prevent dust from entering your eye.
And then have a closer look – you have all that very fine hair on your arms and legs, you can hardly see. What happens when you very, very gently touch this hair or blow at it? It tickles! This very fine body hair helps humans to feel if something is touching you.
In spiders, it is quite similar. Their body hair helps them to feel if something is touching them. Say you took a paintbrush and gently touched a spider with it (don’t do this without an adult there, of course, because some spiders can be dangerous). This touch will make the spider’s hairs bend. The spider will feel that something big is touching it and probably think “Oh dear, there is something that wants to eat me!” and run off.
Like you, spiders have different types of hairs. But spiders can do much more cool things with their hair then we can with ours (except, maybe that we are superior in styling our hair in a cool fashion).
Have you ever seen a spider with ears? Well, no (that would actually look funny!) That’s because spiders use hairs on their legs to listen! Sounds unbelievable, but that’s how it is.
Does a spider have a nose? I’ve never seen one, and I have seen lots and lots of spiders. To smell, spiders use hairs.
Does a spider have a tongue? Nope. They use – you guessed it – hairs!
So spiders can feel, listen, smell and taste with their hairy legs. Pretty cool, right?
Some spiders can also use their hairs to grip onto a very flat surface – this is why you see spiders walking happily across a window, a ceiling or high up on a wall. (This is also how Spiderman does it, by the way).
Actually, not all spiders than can do that. Only the ones that have special Spiderman-hairs on their feet can do it. These Spiderman-hairs are tiny and have even tinier hairs on them – hairs on hairs. Scientists are trying to learn from these spiders and create Spiderman gloves. With such gloves you could climb up a skyscraper like a spider!
Spiders can be quite colourful. Do you know peacock spiders? Here is a picture of one:
The peacock spider’s colours come from special hairs on its legs and body and they are used to impress other peacock spider mates and find a partner. The peacock spider boy waves his coloured hairy legs in a funky dance to tell the spider girl, “I am the best guy you’ll ever find”. Such a show-off! Here’s how they look when they dance:
So you see, spiders need hairs for quite a lot of things in their life – and that is why they have hairy legs.
Jonas Wolff, Research Fellow in the Department of Biological Sciences, Macquarie University
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