Gecko

Quick Take

• Geckos use a physical force more commonly associated with chemistry labs than lizard feet, and scientists are racing to copy it. See their climbing science →
• One gecko species was declared extinct, then turned up alive over a century later. Find out which one and where it was hiding. Explore endangered species →
• A gecko's pregnancy can last anywhere from weeks to years depending on the species, and the extreme end of that range is hard to believe. See gestation details →
• Some geckos can reproduce without a mate, which is just one of several survival tricks that make them unlike almost any other reptile. Discover parthenogenesis origins →

Geckos have been around for at least 100 million years. Scientists have found geckos preserved in amber that dates back to the Cretaceous Period, and those specimens look remarkably like the gentle little lizards you’ll find in so many parts of the world today.

There are approximately 2,000 gecko species, and they vary in size from the Jaragua Sphaero dwarf gecko to the New Caledonian giant gecko, which can grow to around 14 to 17 inches in total length and weigh up to 10 ounces.

Geckos thrive in practically every habitat, including rainforests, mountains, and deserts, so long as average temperatures reach 72 degrees Fahrenheit.

5 Incredible Gecko Facts

• These reptiles can climb practically every vertical surface effortlessly thanks to the Van der Waals forces generated by hundreds of thousands of tiny hairs on their toes.
• Geckos are among the few non-avian reptiles notable for their vocal abilities, often producing sounds with tonal or harmonic qualities.
• These reptiles clean their eyes by licking them.
• When they lose their tails to predators, they can regenerate new tails.
• These reptiles replace their teeth by growing new ones every three to four months.

Evolution and Origins

Researchers have traced the oldest known gecko fossil to approximately 100 million years ago. Reptiles are thought to have descended from a common ancestor, which can be dated back to the Carboniferous Period, which occurred between approximately 359 and 299 million years ago. The oldest known reptile fossil is Hylonomus, and it has been estimated to date back 315 million years.

The exact time when geckos developed their remarkable climbing feet is unknown. A fossil dated to 100 million years ago showed the tail and feet of a gecko, including the setae, or tiny hairs on the feet. Other adaptations that have been observed in modern species, like camouflage and the leaf-tailed gecko’s distinct tail resembling a dried leaf, demonstrate how far they have come from their ancient ancestor.

Human beings have been in awe of the gecko for its ability to stick to virtually any surface. Its feet are able to do this by using Van Der Waals forces, an electrical attraction between molecules, and the structure that makes it possible is called setae, which consist of millions of individual hairs. Scientists have even been working to recreate these hairs in order to produce their own adhesives.

Humans have identified five distinct subfamilies of geckos, and there are currently over 2,000 known species of these reptiles in the world, according to the Global Gecko Association. Geckos come in various colors and shades, with some being able to blend in with their surroundings. Additionally, some female geckos have the remarkable ability to reproduce without a mate, such as the mourning geckos.

Geckos have adapted to their environment in many ways over time. Leopard geckos, for example, are unable to climb walls, but they can burrow to escape from extreme temperatures. Most geckos share the same type of feet and eyes, and they also have a defense mechanism that releases a foul odor and feces when attacked by predators. Geckos typically eat small insects such as cockroaches and worms. This wide range of adaptations is evidence of how the species has evolved to survive in different environments.

Classification and Scientific Name

These animals belong to a taxonomic group that shares the designation “squamate reptiles.” “Squamate” is derived from the Latin word “squamatus,” which means scaly, although geckos themselves do have scales. They belong to the infraorder Gekkota, a name thought to derive from the Indonesian-Malay “gēkoq,” which is a transliteration of the sound this animal makes.

The infraorder Gekkota is comprised of seven families:

• Diplodactylidae: This family includes 137 species in Australia and New Caledonia. Its scientific name is derived from the Greek words for double (“diplo”) and finger (“daktylos”). The crested gecko, a popular pet, is a member of this family.
• Carphodactylidae: Carphodactylidae is another family of Australian geckos, comprising 30 species. Its scientific name derives from the Greek words for finger and straw (“karphos”).
• Pygopodidae: Pygopodidae look like snakes but are really geckos. The family consists of 35 species, native to Australia and New Guinea. “Pygo” is a Greek word for rump while “podi” is the Greek word for feet, so the family’s name roughly means “feet in their bottom.”
• Eublepharidae: Eublepharidae is a family of 30 species found in Asia, Africa, and North America. They are distinguished from other species by their movable eyelids and their lack of adhesive toepads. This genus includes the leopard, the fat-tailed, and the clawed gecko.
• Sphaerodactylidae: The Sphaerodactylidae family includes more than 200 species distributed throughout all parts of the world. The scientific name derives from the Greek words for round (“sphaero”) and finger (“dactyl”).
• Phyllodactylidae: “Phyllo” is the Greek word for leaf, and many of the 148 species that belong to this family are known as leaf-toed geckos. Phyllodactylidae is found in all parts of the world.
• Gekkonidae: Gekkonidae, or the common gecko, is the most widespread family, containing more than 950 species. Well-known species include the house, the tokay, the leaf-tailed, and the day gecko.

Appearance

These reptiles are small lizards with stubby bodies, large heads, tails, and — except for members of the Pygopodidae family — prominent limbs. The animal’s color varies widely across species. The majority are grey or brown, the better to blend in with the rocks, sand, and dirt around them and so to escape the notice of predators. However, the leopard gecko has bright yellow skin covered with brown spots. Some geckos are electric blue. The crested gecko is orange or red, while the tokay gecko has bright orange spots.

Their tails also vary widely in shape and morphology, depending upon the species. Some are long and tapering, while others are shorter and blunter or even globular. These reptiles store fat in their tails so they’ll have access to calories when food sources are scarce. Their tails have evolved to fall off easily when the animal is pursued by predators. When this happens, the animal will regenerate its tail. Their tails actually have their own nerve control center that allows the tail to move and lunge independently for up to half an hour after separation from the body.

These reptiles have approximately 100 teeth. Their teeth don’t grind down because they replace their teeth every three to four months.

Their skin is covered with millions of infinitesimal, hair-like spines that are very soft to the touch. These spines trap water droplets that keep dust and other air contaminants away from the gecko’s skin. The microscopic hairs that cover their toes are called “setae.” These hairs work differently than the hair that covers the animal’s body. Setae are actually tiny enough to activate molecular Van der Waals forces that enable geckos to easily climb vertical surfaces, like walls, and even to move comfortably on ceilings.

Although a few species are active during the day, they are primarily nocturnal animals, and the design of their eyes shows it. All but a few species have translucent membranes covering their eyes instead of eyelids. They lick their eyeballs to keep them clean. (The leopard gecko is unique here in having movable eyelids.) Their pupils are vertical, and their eyes can be up to 350 times as sensitive to light as human eyes. These lizards also have a sophisticated auditory system; they’re capable of hearing sounds pitched at high frequencies that other reptiles cannot hear.

Behavior

Though these reptiles are not particularly social animals, they have a sophisticated vocal communication system when compared with other lizards. They have true vocal cords. They bark and chirp to define their territory, attract mates, and elude predators; they also hiss and emit high-pitched squeaks. The New Caledonian gecko has such a distinctive growl that native tribes of those islands dubbed it “the devil in the trees.” The leaf-tailed gecko of Madagascar emits a distress call that many liken to a child’s scream.

They also use their tails to communicate with other geckos. Slow, wiggling movements indicate awareness of another animal’s presence, while more vigorous shakes are defensive maneuvers designed to distract or evade predators.

Another characteristic of their behavior is their head shaking. This movement is associated with feeding, and it helps the animal pass food from its throat to its stomach.

Most species are nocturnal. The night is the time when they climb most actively. Geckos are swift runners too; flat-tailed house geckos have been clocked at three feet per second, and they can scamper over the surface of the water.

Habitat

These reptiles live in a variety of warm habitats on every continent of the globe except Antarctica. The immense amount of morphological variation found in different species reflects the ways that they have evolved to fit into their specific habitats. The Northland tree species, for example, owes its bright green color to the New Zealand forests and scrublands it inhabits. The leopard gecko, with its yellowish skin and black spots, blends in well with the semi-desert terrain of its native Pakistan, India, and Afghanistan. Red-spotted tokay species are well concealed in the lowland or submontane rainforests of Southeast Asia, while black-spotted tokay species have adapted to the rockier regions of Vietnam and China.

Diet

These reptiles are primarily insectivores, but they also eat worms, fruit, and flower nectar. Leaf-tailed geckos like to snack on land snails. Large species of geckos, such as the New Caledonian gecko, have even been known to eat small birds and rodents.

What do geckos eat?

Insects, worms, fruit, and flower nectar.

Predators and Threats

Predators include snakes, birds, spiders, and species introduced by humans, such as dogs and cats. In the tropical rainforests of northern South America, these animals are stalked by the much smaller goliath tarantula, which uses its venom to paralyze the gecko and liquefy its flesh. Raptor birds such as hawks and owls typically live in climates too cold for geckos, but when temperatures drop below freezing and these birds travel south, these reptiles become a favorite prey.

Most species aren’t in danger of extinction, but a few species are on the International Union for Conservation of Nature’s Red List. The crested gecko of New Caledonia, for example, was thought to be extinct for many years after its initial sighting in 1866 until it was rediscovered in 1994. Two other New Caledonian species, Bavayia goroensis and Bavayia ornata, are on the Red List because mining activities are shrinking their habitats.

What eats geckos?

Snakes, birds, spiders, and cats.

Reproduction and Life Cycle

Males attract females by making distinct mating sounds and by vibrating their tails. While mating, the male grasps the skin at the back of the female’s neck in his jaws and tucks his tail beneath her abdomen, bringing the animals’ cloacal openings in proximity so that fertilization can occur. Some species, however, such as the mourning gecko found in Central and South America, can reproduce through parthenogenesis.

Most of these animals lay eggs. Gestation periods vary widely in length: The leopard gecko may lay her eggs 16 to 22 days after mating, while a harlequin gecko’s pregnancy can last three to four years. Forty-three species endemic to New Zealand give birth to live young.

The typical egg clutch size is two, and the eggs are laid on the ground beneath rocks and tree bark. Their eggs can take between 35 and 90 days to hatch. Females show no interest in eggs or hatchlings once they’ve laid their eggs. Though many hatchlings have body markings that are different from those of adults, they move, behave, and respond to their environments exactly like adults.

In captivity, these reptiles have relatively long lifespans. Leopard geckos, for example, typically live between 15 and 20 years. In the wild, they live for approximately five years if they aren’t preyed upon. A study in New Zealand found wild geckos that were believed to be at least 36 years old, which is substantially past the average lifespan of a gecko.

Population

Scientists believe that these reptiles originated in Southeast Asia sometime during the Lower Cretaceous, but they are now found in large numbers in practically every place in the world where the average temperature is 72 degrees Fahrenheit or higher. Estimating their total population is impossible.

Conservation

Several species of geckos have been identified as endangered or critically endangered. These include the Achoque gecko (Gonatodes albogularis), Dwarf Gecko (Sphaerodactylus ariasae), and Okinawa Leaf-toed Gecko (Hemidactylus mabouia). The main threats to their survival include habitat loss due to urbanization, deforestation, and agricultural expansion, as well as collection for the exotic pet trade and roadkill from increasing traffic in their habitats.

Additionally, invasive species can compete with native geckos for food sources and nesting sites. To help ensure these creatures survive, conservation efforts should include responsible land use practices such as sustainable forestry, research into population dynamics, and the creation of protected areas for vulnerable species.

Geckos In the Zoo

Every zoo with a reptile house is likely to exhibit at least a few gecko specimens. Zoos with noteworthy reptile collections include the San Diego Zoo, the Fort Worth Zoo, the Saint Louis Zoo, the Los Angeles Zoo, and the Bronx Zoo.