For this week’s picture, I present to you a well-adapted (if poorly camouflaged) little climber:
I’ve never lived any place where geckos are natives, and took this shot on vacation in Hawaii some years back — but I’ve always found their ability to walk on and adhere to walls and ceilings amazing. This little guy, by the way, is comfortably attached to the frame of a sliding glass patio door.
It’s really only been in the past few years that people have figured out how geckos so casually accomplish this feat of the feet. It turns out that the bottoms of a gecko’s feet are covered with millions of tiny hairs called setae — each only twice as long as a human hair is wide. Then each seta is subdivided at the end into a thousand or so smaller hairs called spatulae, each thinner than the wavelength of visible light. This gives a gecko’s foot so much surface area that it can adhere to even the slickest surface using van der Waal’s force, an ordinarily weak inter-molecular force. Together, all four of a gecko’s feet could hold about 90 pounds of weight!
Needless to say, now that the gecko’s feet are a bit better understood, a whole range of new uses for this approach are being developed. Surgical adhesives, sure-footed robots, and super-sticky tape are on the menu for the (hopefully) not-too-distant future.
For more info on the gecko, I’d recommend you check out Cabinet of Wonders. Also, there’s a well written press release that just came out last week on the latest gecko-based creation using carbon nanotubes (still outrageously expensive, but promising…).