Lizards slithering up walls or dangling precariously from overhead lights are a common sight in tropical countries. These slimy creatures zipping up walls are called geckos. They are the only lizard species that make any sound, other than hissing — in fact they make a loud clicking noise that sounds like “gecko”, hence the name.

Recent studies show that the gecko’s ability to cling on to surfaces could well lead to the creation of the world’s first non-sticky, self-cleaning adhesive! According to scientists at the University of California, gecko feet function a bit like the tape we use for sticking. Of course a gecko’s tenacious hold is far, far stronger than any earthly tape.

How Lizards Defy Gravity
How Lizards Defy Gravity

Scientist have often analysed the feet of geckos in order to understand the lizard’s sticking prowess. For years scientists assumed that the pads on the lizard’s feet created suction. This idea was discarded when experiments proved that lizards continued to cling on to surfaces — even in a vacuum.

Researchers have only recently discovered what really enables geckos to scuttle across ceilings and walls without losing their grip. By carefully examining the tiny hair that cover a gecko’s toes, the team discovered that the microscopic hair split up into even tinier pads called spatulae. These spatulae are incredibly minute (each is about a lakh times smaller than an inch). The combined adhesive property of these pads is quite impressive — in fact the adhesive power is so effective that a gecko can dangle from the ceiling by one toe!

By filming geckos, running up walls, the scientists discovered that geckos carefully uncurl their toes as they take each step. And when they take their feet off the wall they simply reverse this process – an act similar to the peeling off of tape from a surface. The tiny hair on the toes rolls out to stick to the surface, as the gecko walks, and then peels off as the gecko lifts its toes. Curiously enough gecko feet do not contain any gummy substances, so the lizards do not use glue or liquid to grab on. Nor do they need a special surface to cling on to – like Velcro requires.

How Lizards Defy Gravity
How Lizards Defy Gravity [Illustration by Sudheer Nath]

The fact that gecko hairs function very, very differently from a regular adhesive (or Velcro) is of great interest to scientists. Researchers are now keen to use gecko hairs to make the world’s first dry adhesives! Scientists also noticed that gecko hairs are self cleaning – apparently, the teeny hair, on the gecko’s toes, always remain ultra-clean and springy. Scientists have yet to figure out why, and when they do – we can get rid of messy glue and opt for a dry, self-cleaning alternative.