Other than their adhesive feet and lasting fame from a series of car insurance commercials, you probably don't know a whole lot about geckos. And yet this category of more than 1,100 species of lizard is filled with fascinating surprises. Delve into the world of the geckos and learn how they stick to ceilings, fly through trees, change color and even call to each other with "barks"!
1. Geckos' amazing toes help them stick to any surface except Teflon.
One of their most famous talents is their ability to scurry along slick surfaces — even glass windows or across ceilings. The only surface that geckos can't stick to is Teflon. Well, dry Teflon. Add water, however, and geckos can stick even to this seemingly impossible surface! They do this through specialized toe pads.
Contrary to popular belief, geckos don’t have “sticky” toes, as if covered with glue. They cling with incredible ease thanks to nanoscale hairs — thousands of them — that line every toe. American Scientist explains:
[G]ecko toes work nothing like pressure-sensitive adhesives (found on adhesive tape), which are soft enough to flow and make intimate, continuous surface contact. Instead, gecko toes bear ridges covered with arrays of stiff, hairlike setae. Each seta branches into hundreds of tiny endings that touch the surface and engage intermolecular van der Waals forces. Together, the 6.5 million setae on a 50-gram gecko generate enough force to support the weight of two people. Furthermore, gecko toes detach within milliseconds, stick to nearly every material, and neither stay dirty nor self-adhere.
This fantastic adaptation of geckos has inspired scientists to look for ways to mimic this cling-ability, improving everything from medical bandages to self-cleaning tires.
2. Geckos' eyes are 350 times more sensitive to light than human eyes.
Most geckos species are nocturnal, and they are particularly well-adapted to hunting in the dark.
According to a study of the helmet gecko, “Tarentola chazaliae, discriminates colors in dim moonlight when humans are color blind. The sensitivity of the helmet gecko eye has been calculated to be 350 times higher than human cone vision at the color vision threshold. The optics and the large cones of the gecko are important reasons why they can use color vision at low light intensities.”
While we would hardly be able to make out color at all in dim moonlight, geckos can go about their business in what is, to them, still a colorful world.
Jennifer Greene writes on The Reptile Times:
Geckos in particular have eyes sensitive to blue and green, which makes sense when you consider that in most habitats, the wavelengths of light being reflected most fall into that color range. Instead of red, the cone cells in gecko eyes see into the UV range … So are they blind on moonless nights? Not quite – there are other sources of light, such as star light, as well as other reflective surfaces bouncing light off of each other, leaving enough light for the blue and green seeing geckos to still be active.
3. Geckos are able to produce various sounds for communication, including barks, chirps and clicks.
Unlike most lizards, geckos are able to vocalize. They make clicks, chirps, and other sounds to communicate with fellow geckos.
According to National Geographic:
"The chirping, sometimes called ‘barking,’ of geckos is either a territorial or courtship display,” to ward off other males or attract females, Peter Zani, a biologist at the University of Wisconsin-Stevens Point, says via email. Some noteworthy noisemakers, Zani says, are Mediterranean house geckos, which squeak during fights and flirtatiously click to draw females. The turnip-tailed gecko of Central and South America makes territory-marking clicks thought to mimic insects. And the New Caledonian gecko, the largest gecko at 14 inches (36 centimeters), has a growl that earned it the local nickname of “the devil in the trees.” The sound of one gecko is even embedded in its name: Male tokay geckos, from Asia, make a loud, persistent mating call, “tokay-tokay!”
The purpose of the sounds could be to warn away competitors from a territory, to avoid direct fighting, or to attract mates, depending on the species and situation. But if you ever hear an odd chirping in your house at night, you might just have a gecko as a guest.
4. Some species of geckos have no legs and look more like snakes.
There are upward of 35 species of lizard in the Pygopodidae family. This family falls under the clade of Gekkota, which includes six families of geckos. These species — all of which are endemic to Australia and New Guinea — lack forelimbs and have only vestigial hindlimbs that look more like flaps. The species are usually called legless lizards, snake lizards or, thanks to those flap-like back feet, flap-footed lizards.
Like other species of gecko, pygopods can vocalize, emitting high-pitched squeaks for communication. They also have stand-out hearing, and are capable of hearing tones higher than those detectable by any other reptile species.
5. Most geckos can detach their tails — and regrow them later if necessary.
Like many species of lizard, geckos are able to drop their tails as a response to predation. When a gecko is grabbed, the tail drops off and continues to twitch and thrash about, providing a great distraction that might allow the gecko to escape from a hungry predator. Geckos also drop their tails as a response to stress, infection or if the tail itself is grabbed.
Amazingly, geckos drop their tails along a pre-scored or “dotted line,” so to speak. It's a design that allows a gecko to lose its tail quickly and with minimal damage to the rest of its body.
According to LiveScience:
To find out how the lizards lose their tails, the team used several types of microscopes to visualize the lizard tail's structure and also observed the appendage shedding in euthanized geckos. They found the gecko tail had zigzag lines that separated segments of the tail, forming a "precut" line. When the geckos shed their tail, they left behind a pointy, crown-shaped stump. At the stump, the team was able to see bizarre, mushroom-shaped structures. Those structures, the team hypothesizes, form to reduce the adhesive, or sticky, forces and allow the gecko tail to rip off.
A gecko can regrow its dropped tail, though the new tail will likely be shorter, more blunt, and colored a bit differently than the original tail. The crested gecko is one species that cannot regrow its tail — once it's gone, it's gone.
6. Geckos use their tails to store fat and nutrients for lean times.
Losing a tail isn't a favorable event for a gecko, not only because it's an energy-intensive process to regrow a whole tail, but also because a gecko stores nutrients and fat in its tail as a protection against times when food is scarce.
Because of this, for many species a plump, well-rounded tail is a good way to gauge the individual gecko's health. Depending on the species, a thin tail might indicate starvation or illness.
7. Geckos can live a long, long time.
Geckos range in life span depending on the species, but many will live around five years in the wild. Several species that are popular as pets, however, can live quite a bit longer.
In captivity, a well-tended gecko can live between 10-20 years. Leopard geckos average between 15-20 years, though the longest lived individual is recorded at 27 years old.
8. Most species of gecko don’t have eyelids, so they lick their eyes to clean them.
Perhaps one of the oddest facts about geckos is that most species lack eyelids. Because they cannot blink, they lick their eyes to keep them clean and moist. (Well, technically, they're licking the transparent membrane that covers the eyeball.)
Backwater Reptiles explains:
The gecko species that can’t blink have fixed, immovable eyelids. Examples of species of gecko with these types of eyelids are Tokay geckos (Gekko gecko), crested geckos (Rhacodactylus cilliatus), 52 species of day geckos (Phelsuma sp.), and house geckos (Hemidactylus ssp.). These types of geckos have what is called a spectacle, or a clear scale over their eyes instead of an eyelid. It is often said that a gecko’s tongue is like a windshield wiper and the spectacle is like a windshield... licking their eyes also helps to keep their spectacles from drying out and serves the same function as when we humans blink.
9. Geckos are masters of color.
It’s not only chameleons that can change color to match their surroundings. Geckos can, too. What’s more, they can blend into their environment without even seeing their surroundings!
In studying Moorish geckos Domenico Fulgione and his team discovered that it isn’t their vision that the geckos use to blend in, but rather the skin of their torso. They sense, rather than see, their surroundings to camouflage themselves. Ed Yong reports on National Geographic:
They found that the skin is rife with opsins — light-sensitive proteins that are the basis of animal vision. When light enters your eyes, opsins in your retinas respond by triggering chemical reactions that send signals to your brain. That’s how you see. The Moorish gecko has plenty of opsins in its eyes too, but the team also found these proteins all over the skin of its torso. It’s especially common in the lizard’s flanks, and in cells called melanophores that are filled with dark pigments. The researchers think that the flank opsins can respond to surrounding light levels and automatically adjust the gecko’s colour. If they’re right, the lizard has a kind of distributed vision that is independent of its eyes, and perhaps its brain. In other words, it can “see” with its skin.
Other species of gecko are particularly adapted to blend in with their habitat based on their skin patterns, which make them look like lichen, textured rock or moss, such as the mossy leaf-tailed gecko, the Wyberba leaf-tailed gecko pictured above, or the satanic leaf-tailed gecko, pictured below.
10. The satanic leaf gecko perfectly mimics dead leaves.
Speaking of, this species is worth discussing, since few geckos are so incredibly well adapted to look exactly like a leaf — and a demonic leaf, at that! This species of gecko is identical to dry leaves found on the forest floor or even among branches, right down to the veined skin and the insect-nibbled notches.
Endemic to Madagascar, the species relies on this uncanny resemblance to dead leaves to escape the detection of predators. To complete the masquerade, satanic leaf-tailed geckos will even hang from branches to look like a leaf curling away from a stem. Wired notes:
They’ll spend the day hanging motionless off of branches or snuggling among dead leaves, often twisting their leafy tails around their bodies. Other larger species in the satanic’s genus have still another strategy for sleeping safely during the day, flattening their bodies against tree trunks and limbs, making good use of those famously grippy feet… Fringes and flaps along the edges of their bodies help erase their outlines and shadows, dissolving the geckos into the bark.
Ultimately, the satanic leaf-tailed gecko is a stand-out creature that you’d be hard-pressed to locate!
11. Some gecko species can fly! (Well, sort of).
The flying gecko, or parachute gecko, is a genus of arboreal gecko species found in Southeast Asia. While they aren’t capable of independent flight, they get their name from their ability to glide using the flaps of skin found on their feet and their flat, rudder-like tails.
The flying gecko can glide up to 200 feet in a single bound, despite measuring only about 6 to 8 inches in body length.
These geckos, while skittish, are relatively popular in the pet trade.
12. The smallest gecko species is less than 2 centimeters in length.
Geckos vary in size, but the most diminutive of species can fit on a dime. The Jaragua sphaero, or dwarf gecko, is one of the world's smallest reptiles. This and another gecko species, S. parthenopion, measure just 0.63 inches in length from snout to tail. The small gecko has an equally small range, as it's believed to be limited to only the Jaragua National Park in the Dominican Republic, and Beata Island.
One of the biologists who discovered the minute lizard, Blair Hedges, told reporters, "Our discovery illustrates that we still don't know everything about the Earth's species, even in areas that are very close to the United States... We did not even know the species existed, although the area has been studied by biologists for several hundred years."
Leave it to geckos to keep us guessing.