Lizard

Lizards live on almost every land.

They can be tiny or very big. The Komodo dragon is a huge lizard.

Most lizards have four legs and a long tail. Some lizards do not have legs at all.

Their skin has hard scales. These scales help them stay wet in dry places. As they grow, they shed their skin in pieces.

Many lizards eat bugs. Some big ones eat large animals. They use long tongues to find food.

Lizards like to sit in the sun. The sun helps them get warm. This heat helps them move and play.

Lizards are amazing animals to see in the wild!

Lizards are a big group of reptiles.

There are over 7,000 kinds of lizards. They live on almost every continent.

Some are tiny, like small geckos. Others are very big. The Komodo dragon can grow to 3 meters long.

Most lizards have four legs and long tails. They use their legs to run with a side-to-side motion. Some lizards have lost their legs. These look like snakes. Other lizards can glide through the air. Many lizards have scales on their skin. These scales are made of keratin. They protect the animal. They also stop water from leaving the body. This helps lizards live in dry deserts.

Lizards use their senses to find food. Many eat insects. Some eat large mammals. Some use long tongues to sense the world. They flick their tongues to gather scent. Geckos use their tongues to lick their eyes clean. Geckos also have special pads on their toes. These pads help them climb walls.

Most lizards are active during the day. They must sit in the sun to get warm. This is how they get power to move.

Lizards are a huge group of reptiles with over 7,000 different species.

You can find them on every continent except for Antarctica. They also live on many island chains in the ocean.

These animals come in many different shapes and sizes. Some are tiny, like the Brookesia micra chameleon. Others are very large, like the 3-meter-long Komodo dragon.

Most lizards are carnivores, which means they eat meat. Small ones eat insects, but Komodo dragons eat large mammals like water buffalo.

Lizards have many ways to move and stay safe.

Most have four legs and run with a side-to-side motion. Some have lost their legs and look like snakes. Others, like the Draco lizard, can glide through the air.

To protect themselves, many lizards use camouflage or even venom. Some can even drop and regrow their tails if a predator grabs them.

Their skin is covered in scales made of keratin. These scales act like a shield and stop water from escaping. This helps them live in very dry deserts.

Lizards use special tools to sense the world around them. Many lizards flick long tongues to gather scents. This helps them use a special organ to sense their environment.

Geckos are different because they use their tongues to lick their eyes clean. Geckos and chameleons also have special toe pads. These pads use tiny hair-like structures called setae to stick to walls.

This allows them to climb glass or ceilings without any liquid glue. Some lizards even have a "parietal eye" on their heads to detect movement from above.

Lizards have interesting ways of growing their families.

Most lizards lay eggs, which are called being oviparous. These eggs can have leathery shells or hard, calcified shells.

Some species, about 20 percent, give birth to live young. This is called viviparity. In some special cases, a female can even have babies without a male. This is called parthenogenesis.

For some lizards, the temperature of the nest decides if the babies will be male or female.

Understanding lizards helps us learn how life works on Earth. They are ectotherms, which means they cannot make their own body heat. They must bask in the sun to get enough energy to move.

Scientists even study lizard venom to try and make new medicines. This is because lizard venom contains special proteins. By studying these small creatures, we learn about the history of all reptiles. Even the way they breathe is a mystery that scientists are still solving.

Lizards are a massive and diverse group of reptiles within the order Squamata. This group includes over 7,000 different species found on every continent except Antarctica. They also inhabit most major oceanic island chains.

While most people think of lizards as a single group, they are actually paraphyletic. This means some lizards are more closely related to snakes than they are to other lizards. They vary wildly in size. Some, like the chameleon *Brookesia micra*, are only a few centimeters long. Others, like the Komodo dragon, can reach lengths of 3 meters.

Most lizards possess a specific anatomy that distinguishes them from other reptiles. They typically have rounded torsos, elevated heads on short necks, and four limbs. However, some lineages have become legless, resulting in long, snake-like bodies.

A key skeletal feature is the movable quadrate bone. This bone allows for jaw movement and distinguishes them from rhynchocephalians, which have more rigid skulls. Their skin is covered in scales made of keratin. These scales provide a protective barrier and reduce water loss through evaporation. This adaptation is vital for surviving in extremely dry desert environments. Unlike snakes, which shed their skin in one piece, lizards slough their skin in several pieces as they grow.

Lizards have evolved many specialized ways to move and interact with their habitats. Most are quadrupedal and use a side-to-side gait. This movement creates a challenge called Carrier's constraint. This constraint involves body bending that can interfere with breathing during movement, which limits their endurance.

To overcome environmental obstacles, some species have developed amazing skills. The *Draco* genus can glide through the air for significant distances. Some species, like the basilisk, can actually run across the surface of water.

Others, such as geckos and chameleons, have modified scales on their toes. These form adhesive pads made of millions of tiny hair-like structures called setae. These setae use van der Waals forces to stick to surfaces without any liquid adhesive.

Sensory perception in lizards is highly varied depending on their specific environment. Many lizards, such as monitor lizards and whiptails, use a forked tongue to sample the environment. They flick their tongues to transfer molecules to the vomeronasal organ. This organ is responsible for chemosensation, a process similar to smelling or tasting. Geckos use their tongues for a different purpose: licking their eyes clean because they lack eyelids. Some lizards, like iguanas, possess a parietal eye on top of their heads. This is a primitive feature with a rudimentary retina and lens. It cannot form images, but it is sensitive to light and movement. This helps the animal detect predators approaching from above.

Lizards also possess complex chemical defenses. While many are insectivores, others are powerful predators. The Komodo dragon is a carnivore that can hunt mammals as large as water buffalo.

Some species are also venomous. For a long time, scientists thought only the Gila monster and Mexican beaded lizard were venomous. We now know that several monitor lizards, including the Komodo dragon, produce venom. The Lace monitor produces venom that causes rapid loss of consciousness and prevents blood clotting. Scientists have found venom-related genes in many lizards, including iguanas. This suggests these genes may have evolved in a common ancestor of lizards and snakes about 200 million years ago.

Reproduction in lizards follows several different biological paths. Most species are oviparous, meaning they lay eggs. These eggs often have leathery shells to allow for water exchange, though desert species may have calcified shells to retain moisture.

About 20 percent of species are viviparous, meaning they give birth to live young. In these species, embryos are nourished via a placenta-like structure. A small minority of species undergo parthenogenesis. This is a form of asexual reproduction where females produce offspring from unfertilized eggs.

In some species, the sex of the offspring is determined by the temperature of the environment during incubation.

Finally, lizards play a critical role in understanding biological systems and evolution. As ectotherms, they rely on external heat sources like sunlight to regulate their body temperature. This behavior, known as thermoregulation, allows them to manage environmental changes. Recent studies into their lung anatomy have also revealed surprises. Scientists found that some lizards have a unidirectional airflow system. This means air moves in a loop through the lungs. This trait was previously thought to exist only in birds and crocodilians, suggesting it may be an ancient trait for many reptiles.