Lizard facts

Lizards are one of the most diverse and adaptable groups of reptiles. They range from tiny, delicate geckos that can fit on your fingertip to massive and venomous Komodo dragons. Lizards have evolved to live all over the world and thrive in a wide variety of habitats, from deserts to jungles and even alongside us in urban environments. Some have evolved without legs, while others can amputate their tails if they feel threatened.

• Some lizards have forked tongues like snakes, and they use them to sense their surroundings. Other lizards, like chameleons, have stretchy and sticky tongues that they shoot out to catch prey. One chameleon species can accelerate their tongues from 0 to 100kph in under a tenth of a second!¹
• Komodo dragons are considered venomous, and their serrated teeth are reinforced with iron-enriched coatings.²
• Geckos have sticky pads on their toes that allow them to grip onto surfaces and hang upside down. If they fall, they can flick their tail around and land on their feet like an acrobat.
• The basilisk lizard can sprint across the water at over 11 km/h using specialized foot scales, while water anoles trap air in a bubble over their nostrils, allowing them to stay submerged for up to 20 minutes.³
• Some lizards can reproduce without a mate. The Mexican whiptail lizard species, for instance, is made up of an entirely female population.⁴
• The entire Hawaiian population of gold dust day geckos comes from just eight lizards introduced by a lizard-loving university student.⁵

Lizards are an incredibly varied group of reptiles, ranging from chameleons and geckos to iguanas and monitor lizards.

Some are smooth and others are rough and spiny. Some are colourful and bright while others are dark and camouflage into their surroundings. Some lizards walk and run on water; others are formidable swimmers at great depths. Many lizards can climb on vertical surfaces or hang up upside down from ceilings and branches. Other lizards don’t even have legs, and they spend all their time underground. As of 2025, there are more than 7849 species of lizards split up into about 45 different groups, but scientists are constantly discovering new ones.⁶

“Lizards never fail to astound you with the ways they can make a living,” says Martha Muñoz, a lizard researcher at Yale University. “Lizards dive into the ocean to chew on algae. Lizards are found in places with snow. You know, lizards are found thousands of metres above sea level. They're found in lava craters. You can find them on coastal dunes. You can find them on beaches. You can find them in jungles.”

Yes, chameleons are a type of lizard, like iguanas or geckos. They’ve evolved some specialised features over millennia to thrive in the rainforests, deserts, savannas, and the mountains of Africa and Asia.

For instance, chameleons have specialised bulging eyes that can each move independently from one another.⁷ They have good colour vision to identify prey more readily and stretchy and sticky projectile tongues that they can fling out of their mouths to catch insects with.⁸ Rosette-nosed pygmy chameleons can hurl their ballistic tongues toward their prey at 8,500 feet per second, with a force 264 times the force of gravity – jet fighter acceleration only reaches 7 times the force of gravity.⁹ Chameleons are perfectly adapted for climbing in trees. They have prehensile tails that coil around the branches, and they have feet like birds, with five toes split into two groups so as to form a clasp around tree limbs.¹⁰ Their feet also have sticky hairs that latch onto different surfaces.¹¹

Chameleons’ most famous adaptation is their ability to change colour. Using specialized cells called chromatophores, chameleons can change the colour of their skin, including greens, blues, reds, yellows, whites, browns, blacks, and purples. While they do use this ability for camouflage, changing colour also helps them regulate their body temperature and communicate with other chameleons.

Yes, geckos are lizards too. Just like giant iguanas and color-changing chameleons, geckos are lizards that have evolved over millennia to adapt to the specific lifestyles and environments they’ve found their niche over time.¹² The suborder Gekkota has almost 2000 species of geckos, making geckos the most diverse type of lizards.¹³

Geckos are smaller and more soft-skinned than most lizards. They have evolved to have sticky pads at the end of each finger so they can crawl up on vertical surfaces and hang out upside down – and they can regulate to turn the stickiness up in times of need.¹⁴ Still, life up in the trees is dangerous and sometimes geckos can fall: to ensure they land on their feet, studies show they twist and turn their tails to spin like acrobats and face the right direction in less than 100 milliseconds.¹⁵

Most geckos only come out at night – they’re nocturnal – but new research suggests some species have adapted to thrive in warm daylight too.¹⁶ Geckos are covered in millions of miniature hairs all over their body so that water doesn’t stick to their skin and so that dirt and debris is flicked off with it too.¹⁷ Some species of gecko don’t have eyelids, and they clean their eyes with a flick of their tongue.

Yes, iguanas are lizards. There are more than 45 recognised iguana species, and they are incredibly diverse.¹⁸ They range from the common green iguana found in the Americas to Fiji’s incredibly rare, banded iguana. Iguanas can be bright lime green, pale indigo, pale orange and yellow, or dark brown and mottled to blend in with their surroundings. Some iguanas spend almost their entire lives living high in the treetops except for laying eggs, while others live among the harsh landscape of the desert.¹⁹ The group also includes the only extant (still living) species of marine lizard, the marine iguana.

Iguanas are generally large for a lizard. Many iguana species have a recognisable crest: a row of long scales running from their head to their tails, like a mohawk hairstyle. They – together with some other types of lizards – also have flaps of skin under their neck, called dewlaps.²⁰ Compared to many other lizards, iguanas also have very thick scales and tough skin.

Lizards are reptiles, so they are “cold-blooded” or, as scientists call it, ectotherms.²¹ This doesn’t mean their blood is literally cold; it just means that their bodies cannot produce their own heat to warm themselves up. Mammals produce their own heat internally by breaking down food and holding it in with insulating layers of fat and fur. Instead, reptiles rely on their surrounding environment to regulate their body temperature.²² “Their ectothermic nature means that they have this intimate partnership with their environment,” says Martha Muñoz, a lizard researcher at Yale University. “Their entire fitness, their way of living. Everything is tied to the environment, and in particular, to temperature.”

To regulate their temperatures, lizards use different behaviours. It’s common to see lizards basking on warm rocks in the sunshine to stay warm or seeking shade or burrowing to cool down during the hottest parts of the day. Some species can even change colour to adjust to the heat or cold. Just like how a dark shirt absorbs more heat than a white one, some lizards make their skin lighter or darker to warm up or cool down.

Lizards can be found on every continent except Antarctica. Because they are cold-blooded, they prefer warmer environments and are best adapted to living in tropical and temperate regions.

Lizards are found in forests, grasslands, at high altitudes on mountains, in burrows in deserts, and even in between houses and buildings in populated cities. Namaqua chameleons live in Africa’s Namib Desert among the sand dunes, while sailfin chameleons live at up to 1,900 metres in the mountains of Cameroon.²³ Leopard geckos are native to the rocky deserts of the Middle East and thrive in sand and clay-gravel soil, whereas the Italian wall lizard loves a bustling city.²⁴ Many gecko species live in forests and valleys in tropical Asia and in areas surrounding the Indo-Pacific.²⁵ About six species of lizards live in Canada.²⁶

Several species of lizards can even be found on remote islands in the middle of the ocean. Like many other small, invasive species, lizards, skinks and geckos can easily travel to new locations by hitching a ride with cargo or human luggage.²⁷ Larger lizards like iguanas can float their way from shore to shore. In 1998, 15 iguanas floated 200 miles from Guadeloupe to Anguilla on a tangle of waterlogged trees that had been tossed into the sea by a hurricane.²⁸

Lizards can vary greatly in size. The largest is the Komodo dragon, reaching up to three metres in length and weighing around 70kg in the wild, although captive individuals can get larger. Smaller lizards include anoles, skinks, geckos and chameleons. The Jaragua dwarf gecko measures a mere 14–18 mm from its snout to the base of its tail, making it small enough to fit on a US 25 cent coin. It has an average weight of just 0.13 grams.²⁹

In 2021, scientists discovered an even tinier lizard when they identified the Brookesia nana chameleon living in the leaf litter of Madagascar.³⁰ It measures in at 13mm in length (about the size of a shoelace tip), making it the smallest lizard in the world.

The majority eat small insects such as flies, beetles, crickets, moths, and grasshoppers. Some species are omnivores and will also eat fruits and leaves. Certain species target social animals like termites and ants, which are easy to find in large groups. Chameleons tend to be sit-and-wait predators who snatch insects off of branches.³¹ Some large chameleons have even been known to eat young birds.³²

Smaller geckos and skinks tend to be a little bit more active than chameleons, as they often chase down some of their prey too.³³ Some are cruising foragers, only occasionally going on the hunt for moving prey, while others actively search for hidden prey under leaf litter and holes.

Monitor lizards, bearded lizards, and Komodo dragons also eat vertebrate animals like other reptiles, birds and their eggs, small mammals like rodents, and amphibians like frogs. Komodos have even been spotted feeding on mammals such as large monkeys, goats, wild boars, deer and even water buffaloes.³⁴

Marine iguanas are vegetarian lizards. They are found around the coast of the Galápagos Islands of Ecuador and forage on red and green algae and local kelps, but they are sometimes found snacking on grasshoppers and crustaceans.³⁵

No, lizards are not slimy (snakes aren’t either!) Lizards are covered in scales made of keratin, the same material as our nails and hair.³⁶ Depending on the lizard species, these scales can vary from being smooth and shiny to being rough, ridged, spiny and very hard to the touch.

Several gecko species have smooth, water-repelling skin (called hydrophobic) that keeps dry and repels dirt and microbes, keeping the gecko clean and healthy.³⁷ On the other hand, the spiny devil and the coast horned lizard are covered in pointy, spiky scales.³⁸

Lizard skin doesn’t grow along with the body like a mammal. Instead, as a lizard grows, the outer layer gradually becomes too tight or worn out. They shed this outer layer in one or several pieces, giving way to fresh skin underneath. This removes parasites or damaged skin, keeping the lizard healthy.³⁹

Some lizards do have forked tongues like snakes – especially monitor lizards such as the Komodo dragon. The forked tongue helps lizards “smell” their environment. By collecting chemicals in the air and delivering them separately to the left and right side of a special sensory organ called the Jacobson’s organ – these lizards have a directional sense of smell, allowing them to navigate and track prey.⁴⁰

Some lizards use camouflage to blend into their surroundings and hide from predators and prey. One of the most impressive is the leaf-tailed gecko from Madagascar. They take camouflage to an almost absurd level – their skin is brown and green so that it resembles lichen and mosses, and it is artificially ribbed to mimic leaf veins. On its eyebrows, horns are spikes that look like twigs, and its tail can even look like a decomposing leaf. There are 22 species of leaf-tailed gecko (in the genus Uroplatus) and each species has tailored its camouflage for the trees they live in: some look mossy, some look like bark and some look like crunchy rotting leaves.⁴¹

Chameleons are also well known for their ability to change colour, but it’s a common misconception that this is solely used for camouflage.⁴² Colour-changing in chameleons is much more about communicating with each other – whether to impress a mate or to fend off a rival. For instance, veiled chameleons flair up their colours as they prepare for a fight: the brighter they get, the more likely they are to approach an opponent and win the feud.

Most lizard species are mute or make very limited vocalisations. Instead, lizards usually communicate through body language. This can take the form of visual signals, body movements, or colour changes. For example, many anole species communicate with one another by doing “push-ups” or bobbing their heads. They’re also known for unfurling their colourful dewlaps, flashy pieces of skin normally tucked under the chin. Many of these behaviours are to signal dominance and physical fitness. Scientists believe that head-bobbing and push-ups help show potential rivals how big and strong a lizard is, discouraging potential conflict.⁴³

Another common signal is changing colour. During the breeding season, male iguanas may develop bright orange or red hues on their heads, necks and body. To other iguanas, brightly coloured scales is a visual signal of strength and reproductive fitness. Driven by hormonal changes (like a boost in testosterone) these colour changes usually fade after the breeding season is over.⁴⁴

Despite most lizards being mute, some communicate through squeaks, chirps, clicks, and barks to either claim their territory or find a mate. For instance, the turnip-tailed gecko makes insect-like clicks and tokay geckos emit a mating call audible to humans as a ‘tokay tokay’ sound. The New Caledonian gecko can growl. Gila monsters make hissing sounds when they fight.

Yes, many species of lizards can swim, especially those that live in environments with lots of water. For example, monitor lizards such as the water monitor are well adapted to aquatic environments and can swim efficiently using their long, muscular tails for propulsion. Even primarily terrestrial species like the Komodo dragon are capable swimmers.⁴⁵

Out of all lizards, marine iguanas are the strongest swimmers. Living a marine lifestyle, these lizards undulate their entire bodies and muscly, flattened tail to propel themselves through the water.⁴⁶ They can hold their breath for at least 15 minutes, and likely much longer.

Swimming isn’t the only way to get around in water, though. The Basilisk lizard, also dubbed the Jesus Christ lizard, is known to run on the surface of water on its two hind feet.⁴⁷ They don’t break surface tension because they have specialized scales on their feet, and they run at more than 11 kilometres per hour.⁴⁸

Lizards have two eyes, but many species also have what scientists call a third, rudimentary eye – the parietal eye.⁴⁹ “It looks kind of like a hole. It's not a hole. It is an actual eye. It has a lens, it has a retina, and it has photoreceptors,” says Michelle Johnson, a lizard researcher from Trinity University. “It can't form visual signals, so it can't see images, but it can detect subtle differences in light.”

The parietal eye helps some species to sense the length of the day and determine whether it’s time to breed or not. In one experiment, Johnson’s team capped the parietal eye of lizards during their breeding season, causing their testes to shrink.

Species of the forest-dwelling Draco lizard genus are able to glide in the sky.⁵⁰ They have especially evolved appendages on their arms that act like large wings that help them parachute among the canopies. The common Draco species is known to climb up to the tops of trees, point their heads towards the ground, jump off, and spread their wings to glide to the bottom – gliding for up to eight metres.⁵¹

Most lizards have legs. However, one subgroup of lizards, aptly called legless lizards, do not. While scientists first thought there was just one species of legless lizard, research over the years has identified hundreds of species, split up into several different groups.

These lizards have evolved without legs because they live underground and spend most of their time burrowing.⁵² Having a much more streamlined body plan, makes it easier to move through the earth (like a worm!)

Legless lizards might look like snakes – but they aren’t. There are a few differences: legless lizards have ear holes, they don’t have forked tongues, they have eyelids, and they don’t have specialised scales on their belly for slithering.⁵³ Still, legless lizards sometimes curl up when threatened to look like a venomous snake, a far more dangerous animal to try and attack.⁵⁴

Not all lizards can stick to surfaces in vertical or upside-down positions, but certain species can. Geckos, in particular, are well known for their climbing ability, enabled by their specially designed feet. Gecko’s feet are one of nature’s most remarkable feats of evolution. They allow geckos to stick and run across vertical walls, ceilings, glass, and even wet or dusty surfaces without using sticky liquids or suction cups. Each gecko foot has five toes, lined with a flattened pad called lamellae. On each of these pads are millions of tiny hairs called setae (1/10th of the width of a human hair) and each of these tiny hairs are thousands of split ends called spatulae (only ~200 nanometres wide). (55) They are so small that the atoms in a spatulae can make extremely close contact with the atoms on a given surface, causing what’s known as the Van der Waals force to take effect.⁵⁶ This is a weak molecular attraction that “pulls” atoms together. When repeated millions of times on each foot, it's strong enough to support the weight of a gecko with just a single toe. Geckos can turn this adhesive effect on and off by changing the angle of the setae, meaning they never get “stuck” to a surface.

Scientists studying geckos in Central and South America even discovered that species with fatter, stickier toepads tend to be more common in areas that have often been hit by the harsh winds of hurricanes and typhoons in the past 70 years.⁵⁷ They think that’s because the extra grip helps them survive during environmental disasters.

This feature isn’t unique to geckos, though. “Anole lizards – which are in a totally different lineage of lizards – they have evolved sticky toepads. And it turns out that certain types of skinks, another super distantly related lineage, also have sticky toepads,” says Martha Muñoz, a lizard researcher at Yale University. “That has evolved independently, again and again, among lineages separated by many, many millions of years.”

Lizards are reptiles, so they cannot breathe underwater – but some have found ingenious solutions to this obstacle.

Marine iguanas, for instance, spend long times in the depths of the sea to forage for their preferred snacks of algae and kelp. They can hold their breath for at least 15 minutes, but probably much longer.

Water anoles are semiaquatic lizards. They’re tiny reptiles living in the tropical forests of southern Costa Rica. They’re called the “chicken nuggets of the forest”, because they’re so small and so easy to prey on.⁵⁸ To escape predators, they’ve evolved a fascinating technique: by blowing a bubble of air over their nostrils (like a scuba tank) they can stay submerged underwater for 20 minutes, hiding away from any predators.

Many lizard species have amazing regenerative abilities and are well known for being able to regrow their tails. This ability often comes in handy when they’re being chased down by a predator. If the hungry animal snatches their tail, many lizards, geckos, and skinks can instantly detach it from their body completely and run away. This is called autotomy.⁵⁹

Lizards lose their tail thanks to special breaking points where the tail can be released.⁶⁰ “Along the tail, there are breakage planes where the bones narrow, the blood vessels constrict and the muscle fibres are more loosely connected,” says Michelle Johnson, a lizard researcher from Trinity University. “So, it's not like the tail can fall off anywhere. It can fall off at many specific points.”

These breakage points seem to be triggered when a certain amount of pressure is applied, but some geckos, Johnson says, seem to do it just because they get scared. “At the drop of a hat, they'll release their tail and run off,” says Johnson.

Once a tail is lost, some species can regenerate it over the next few months to a year.⁶¹ While the original tail has bones and muscles, a regenerated tail is just a rod of cartilage, so it doesn't have the same flexibility as the original tail. It can break off again and regenerate, but the breakage would need to happen higher up along the tail and hit one of those original breakage points. “Sometimes this will accidentally lead to forked tails,” says Johnson.

Some lizards are venomous.

Gila monsters are stout black lizards patterned in pink and bright orange and native to North America. They are famous for being one of the few venomous lizards. They don’t have hollow fangs like snakes. Instead, venom is injected through their grooved teeth in their lower jaw.⁶² Gila monster venom is potent, and can cause severe pain, swelling and nausea, but it is rarely fatal to humans. Deaths are extremely uncommon and usually only a risk in cases of allergic reaction or underlying health issues.

Komodo dragons are also known for being venomous. While scientists originally believed that their toxic bite was a product of nasty bacteria in their mouths, new research indicates that they have a large venom gland.⁶³ The venom contains proteins that lower blood pressure, prevent clotting, and cause shock, which immobilizes prey rapidly. Scientists now believe that venom is the primary weapon, but dangerous bacteria may also play a secondary role, especially in bites that aren’t immediately fatal.⁶⁴

Most lizards lay eggs. Some lay just one at a time, while others lay clutches amounting to almost half their body weight – it depends on the species. Green anoles lay one egg per week in the breeding season⁶⁵, a bearded dragon may lay up to thirty in a single clutch.⁶⁶ Most lizards lay their eggs in warm and protected areas away from predators; under rocks, in sandy soil, in decaying logs or leaves or in extensive burrows. Most species abandon their eggs after laying, though a few species provide limited parental care.

Aside from egg-laying, about a fifth of lizards – including geckos, chameleons, skinks or other species – give birth to live young that look like miniature adult lizards.⁶⁷ Scientists think the Australian three-toed skink may be in the process of transitioning from egg-laying to giving live birth because it’s been caught doing both at the same time: this transition likely has an evolutionary advantage that researchers are trying to get to the bottom of.⁶⁸

Monogamy in lizards is rare: the most common mating system is called polygyny, which is basically where a male mates with several females.⁶⁹

But some species like to couple up for life – how romantic! Shingleback lizards, for instance, regularly form long-term bonds and return to the same partner year after year when mating season rolls around.⁷⁰ Biologists have even observed that if one of the lizards dies, their partner will stay with them, try to nudge them back to life for a while and then struggle to mate again.

A small number of lizard species reproduce on their own. This is called parthenogenesis.⁷¹

Certain female lizards can reproduce asexually, giving birth to unfertilised eggs, without the need for a male. This is common in New Mexico whiptail lizards, where all the lizards from this species are females. The Australian Bynoe's gecko has both sexual and asexual populations.⁷²

Researchers are still trying to figure out whether parthenogenesis is good or bad for evolution.⁷³ But even some lizards known to need a mate to reproduce have also been discovered using parthenogenesis and reproducing without a partner.⁷⁴ Most recently, in 2020, a female Komodo dragon at a zoo in Tennessee gave birth to three hatchlings with no male partner.⁷⁵

Some species of lizards are invasive and have travelled to new locations thanks to human involvement. House geckos reproduce quickly and have spread from the Mediterranean to all areas of the world.⁷⁶ The large Argentine black and white tegus from South America has been introduced to North America through the pet trade.⁷⁷

The most striking of invasive lizards, though, might be the gold dust day gecko of Hawaii. Some of the islands in the Pacific archipelago are overrun by these bright green geckos with beautiful blue, red, and orange patterns on its back. Have a breakfast al fresco and the small, agile lizards may scuttle all over your plate. But they were never meant to be on this island. They are originally from Madagascar, with the entire Hawaiian population originating from just eight lizards released in 1974 by a local university student after a science experiment.⁷⁸

Header image: © Alex | Unsplash

Fun fact image: © Shannon Potter | Unsplash

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Interviews: Interviews with Martha Muñoz, a lizard researcher at Yale University, and Michelle Johnson, a lizard researcher from Trinity University, were conducted in February 2025. Learn more here:

• https://eeb.yale.edu/people/faculty/martha-munoz;
• https://www.trinity.edu/directory/mjohnso9.