5 Reasons Geckos Are the Coolest Lizards

You're used to seeing insects walk on the wall and ceiling or even the underside of a glass table, but among vertebrates, some geckos have the unprecedented ability to cling by their toes to literally anything — with the single exception of dry Teflon. Surprisingly, the reason for this has to do with the gecko's special toe hairs.

"The bottoms of their feet are covered with tiny 'hairs', that make contact with the surface they stand on," says Lin Schwarzkopf, a professor in the college of science and engineering at James Cook University in North Queensland, Australia. "The process is completely dry, with no suction involved. Through a combination of friction and Van der Waals forces – the same forces that cause the meniscus in fluid in a glass — they stick to surfaces, and some can even walk around completely upside down."

Gecko toes — at least the toes of most geckos, as some have regular old lizard feet — are covered with ridges, which are peppered with millions of microscopic bristle-like structures called setae that obey the gecko's every whim, attaching and detaching when the animal wills them to, and they never get gunked up. Evolution: amazing!

Imagine if, instead of blinking, humans stuck out a long, pink, sticky tongue and cleared off our eyeballs, one at a time. That would be disgusting, and yet it's kind of cute when geckos do it.

Geckos rely heavily on their eyesight — they have full-color vision and can see a large spectrum of color even in very dim light. But most geckos don't have eyelids, so their precious eyeballs are covered with little protective scales that need to be wiped off occasionally. So, it's really useful to have a long tongue in situations like these.

You might be wondering how they protect their glittery, bulging eyes from the sun if they don't have lids. Although a few species are diurnal, the majority of geckos spend most daylight hours snoozing; even so, they have vertical pupils that can almost entirely overlap, allowing only a pinhole of light through to see by.

Most lizards don't vocalize — or not very loudly if they do — but geckos have sophisticated vocal communication systems, similar to those of mammals and birds. Gecko vocalization is extremely flexible: Where most other lizards are mute or can only make weak hissing sounds, geckos can bark and click, squeak and chirp in order to attract mates, defend territories or lure potential interlopers away when they get too close. The world's largest gecko, the New Caledonian gecko (Rhacodactylus leachianus), has a low growl that has led the natives of its home islands to nickname it "the devil in the trees."

Geckos mainly eat live insects, and because our houses have a lot of lights — which, in turn, attract a lot of bugs — geckos can often be found inside human habitations.

"Houses have lots of narrow cracks and crevices, which provide shelter for geckos," says Schwarzkopf. "One species of gecko, the invasive Asian house gecko in Australia, loves to hang out in homes, but there are hundreds of species, and most don't [live in] houses!"

It may not surprise you to learn at this point that gecko skin is self-cleaning and antibacterial. Their ability to shed water helps keep them clean in the wild.

"I think the most fascinating thing about geckos is the way their skin repels water," says Schwarzkopf. "It looks just like a freshly waxed car — water beads up and rolls off geckos, carrying dirt and bacteria away from their skin."