Naked Science Forum

Life Sciences => Plant Sciences, Zoology & Evolution => Topic started by: Heather Jameson on 21/06/2019 10:11:30

Title: Who is better at climbing: spiders or geckos??
Post by: Heather Jameson on 21/06/2019 10:11:30
Jay was wondering:

I noticed that in your article titled: "Can we mix human and spider DNA?" that we would be better off taking inspiration from geckos who use Velcro-like pads at the base of their feet. However, spiders work on a similar principle except my understanding is that their way of doing things is better simply due to the fact that they use hair follicles that are rigid enough to allow them to stick to the smoothest surfaces as at a molecular level everything is rough. So the question is which is more efficient having a higher surface area that consists of tiny rigid hairs or a type of Velcro. But in the grand scheme surely both work in similar ways?

What do you think?
Title: Re: Who is better at climbing: spiders or geckos??
Post by: Janus on 21/06/2019 17:03:20
In either case, you run up against the cube-square law.   What works for spiders at their scale just isn't practical when you start to go much larger.   The adhesion strength will be a function of the surface area touching the surface.   If you scale up a spider (or gecko) by 2 times, you increase that surface area by the square, or 4 times.  However, you also increase the volume, and thus its weight, by the cube, or a factor of 8,  The weight that needs to be supported has increased twice as much as the adhesion force holding it to the surface.  Keep going and the spider/gecko will no longer be able to "stick" to a surface enough to support its own weight.