Lizard

Lizard is the everyday name for scaly reptiles that are not snakes, covering over 7,000 species (squamates). Those kept as pets include bearded dragons, iguanas, anoles, and larger types such as savannah monitors and tegus.

Most lizards are fairly small. They typically have a rounded body, a raised head on a short neck, four limbs and a long tail, though some lineages have lost their limbs. Their skin is tough and covered in overlapping keratin scales, which cuts down water loss.

Chameleons stand out with prehensile tails, toes split into two opposed groups for gripping branches, eyes that steer independently, and long sticky tongues. Anoles have adhesive pads under their toes.

Lizards are found on every continent except Antarctica and on most island chains. The oldest undisputed lizards date to the Middle Jurassic, with remains found in Europe, Asia and North Africa. Their variety increased greatly during the Cretaceous.

Their closest living relative is the tuatara of New Zealand. Snakes are descended from lizards, so scientists often regard lizards as a paraphyletic group, and some lizards are more closely related to snakes than they are to other lizards.

People have kept many lizards as pets, among them bearded dragons, iguanas, anoles, savannah monitors and tegus. Lizards also feature in myths and folktales around the world, and in many cultures they symbolise resurrection, perhaps because of their regular shedding of skin.

Most lizards are active by day. As ectotherms, they have limited control over their body temperature and bask in sunlight to warm up enough to be fully active.

Lizards are often territorial, especially males, who defend basking, feeding and nesting spots. Disputes can involve displays, posturing, chasing and biting. Signals include push-ups, head-bobs, bright colours and tail wagging. Male anoles and iguanas have dewlaps, flaps of skin that they expand to signal. Chameleons change colour mainly to communicate, showing brighter colours when aggressive and darker ones when giving up.

Lizards are mostly quiet. Hissing is typical, mostly from larger species during threat displays. They are normally quick and agile, and many rely on hearing to flee at the slightest sound.

Most lizards eat insects and other small invertebrates, while about 2 percent, including many iguanids, are herbivores. Young iguanas eat more insects than adults.

Lizards shed their skin as they grow, in several pieces rather than in one piece as snakes do.

Many lizards, including skinks, can shed their tails to distract a predator. The tail is partially regenerated over a period of weeks.

In the painted dragon lizard, ageing is linked to fading breeding colours, thought to be due to a gradual loss of antioxidant capacity with increasing DNA damage.

This is general awareness only, not veterinary advice. Always consult a vet about your pet's health.

What is a lizard?

It is the common name for squamate reptiles that are not snakes. There are over 7,000 species, from tiny chameleons to the 3 metre Komodo dragon.

Which lizards are kept as pets?

Bearded dragons, iguanas and anoles are all kept, as are monitor lizards such as the savannah monitor and tegus such as the Argentine and red tegu.

Are lizards dangerous to people?

Most lizard species are harmless to humans. Only the very largest, the Komodo dragon, has been known to attack people.

Are bearded dragons and iguanas venomous?

Genes linked to venom have been found in their salivary glands, but most of these are everyday genes found in all cells and may just be evolutionary precursors. Several monitor lizards do produce powerful venom.

When are lizards awake?

Most are active during the day and bask in sunlight to warm up.

Can lizards really drop their tails?

Yes, many can, including skinks. The tail is partially regenerated over a few weeks.

Some lizards can run on their hind legs, and the common basilisk can run across water.

Iguanas have a parietal eye on top of the head. It cannot form images but senses light, dark and movement, helping detect predators from above.

Chameleons can point their eyes in different directions at once.

Horned lizards can squirt foul-tasting blood from near the eyes to about two metres.

Juvenile iguanas eat adult faeces to pick up the gut microflora they need to digest plants.

A captive female Komodo dragon once produced eggs after being apart from males for over two years.

In Central America, green iguanas are nicknamed chicken of the tree.