Who are the better climbers, geckos or spiders?

Eleanor Drinkwater from the Univerisity of York answers this question from Jay...

Eleanor - I absolutely loved researching this question thank you very very much for sending in.  And again I spent a lot of time looking up. And I'm absolutely thrilled to say that it's spiders that are better climbers than geckos. Fascinatingly, they use a very similar mechanism to stick to stuff and it's due to tiny tiny tiny hairs in their fingers.

Chris - Spiders have fingers now?

Eleanor - Yeah. Feet. pads, toes, legs, you know! But tiny tiny tiny hairs which interact with the surfaces that they stick to in a molecular manner, so they’re actually held on by Van der Waals forces. And so if like me you've spent quite a lot of time looking up the difference, you can find out how sticky these animals are to the different surfaces, and then divide them by the bodyweight of the animal. If you compare a jumping spider to a tokay gecko, you will find actually the jumping spider is three times more sticky than the gecko.

Chris - And just to be clear, the way they stick on is that their feet/fingers have tiny hairs and those hairs get very close to the thing they're trying to climb onto. And the electrical attractions between those tiny hair surfaces and the thing they're trying to climb on gives them enormous sticking power.

Eleanor - Yes, it's absolutely incredible.

Chris - So why don't they stick to their own web then?

Eleanor - I don't know.

Chris - One theory I did it hear is that those hairs are very spiky and so the droplets on the web - the sticky bits, if you look at a web it's got regular blobs of sticky stuff - and the spider a) knows where they are so it puts its feet somewhere else and b) the hairs are quite sharp and so the blobs tend to go towards the end like falling off a needle. And so they easily detach whereas other insects that are the prey get stuck in them because they have big juicy hairs that are less easy to disengage so they just get stuck and other bits of the insect body get stuck as well. So the spiders are canny: they know how to use their feet as well as where to put their feet and to have hairy feet that are hairy with sharp hairs, so the spider can detach easily!

Eleanor - However, that stickiness thing comes with a caveat! It depends on the gecko and depends on the spider. You get some geckos and some spiders that are more or less sticky than others!