Science & Technology

This Adorable Foot Belongs to an Animal You'd Never Expect

When it comes to fuzzy faces and furry feet, puppies and kittens are always preferable to flies and spiders. But if you zoom way, way in, spider feet are adorable in their own way. That fur isn't just a way to give household pets a run for their money — it's what gives them their spider superpowers.

What a Fuzzy Bug

Spider feet have more in common with kitten feet than you might think: Not only are they covered in fur — hair, if you want to get technical — but many also have claws. Spiders use their claws to climb rough surfaces and to navigate their webs (if they build them). But claws only go so far. If you're talking about a physics-defying stroll across a ceiling or over a glass window, well, then you'll need hairy feet.

Those densely packed hairs are what help spiders cling to virtually any surface. Each hair is covered with hundreds of thousands of microscopic "setules" that create van der Waals forces, a type of electrical attraction that happens when molecules are very, very close together. The force of this attraction is so strong that some spiders can carry more than 100 times their body weight without unsticking from a surface. And that's a very good thing, as spider expert Sara Goodacre explains to a six-year-old Guardian reader: "If a tarantula fell from a height, it would squish, because all its organs are in its abdomen and it doesn't have a skeleton to protect them. So they have to be very good at holding on."

Multitasking Tendrils

Spider feet are hairy rather than sticky for a few very good reasons. For one thing, hairs are easy to unstick. It's like Velcro: pull the two sides apart directly and you'll have a hard time, but pull from one edge and they come apart easily. By changing the angle of their hairs, spiders can peel themselves away from a surface they'd be firmly attached to at any other angle. According to a 2014 study in the Journal of Experimental Biology, the individual feet don't act alone — opposing legs work together to keep the spider attached, and the further their legs spread out, the sturdier the attachment.

But the hairs do more than stick. They also sense the environment. Just like you have microscopic hairs in your inner ear that help you hear, a spider's hairs can sense the most minuscule pressure difference in the air, whether that's a breeze or sound waves. Those hairs can also "smell" and "taste" by sensing the chemical composition of anything they touch. Whether or not you find a spider's fuzzy limbs cute, we can all agree that they're versatile. If only human body hair was so handy!

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Spiders aren't the only tiny creatures that look prettier up close. See bugs in all of their kaleidoscopic glory in "Microsculpture: Portraits of Insects" by Levon Biss. We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.

Written by Ashley Hamer April 13, 2018

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