The lizard is the common name of various species that are distributed throughout the planet. It is a reptile with scaly skin, and certain species are capable of losing their tail in case of danger, although not all have that capacity.

The iguana belongs to the lizard family
The iguana belongs to the lizard family

Species

There are around 5.000 different species of lizards. The variety between species is very great, from small to large lizards capable of being great predators.

Snakes also belong to the same family but are distinguished by the possession of legs, movable eyelids and external openings in the ears. However, most lizards have lost some of these characteristics. For example, degeneration and loss of limbs is present in crystal lizards. In some geckos the mobile eyelids were lost and in other genera such as Holbrookia and Cophosaurus the external ear openings disappeared.

Features

The lizard ranges from 2 cm (family Gekkonidae) to 3 m in monitor lizards (family Varanidae). The weight ranges from less than 0,5 grams to more than 150 kg.

Almost all species have sharp teeth and tricuspids adapted for grasping and holding. The teeth are present along the margin of the mandible (in the maxillary, premaxillary and dental bones).

They are quadruped and have powerful muscles in the limbs. They are able to accelerate and change direction quickly. Those of the genre (Aspidoscelis) can reach speeds of 29 km / h.

Most species are sexually dimorphic, and males have a wide range of ornaments, such as fans, extendable ruffles and throat spines, horns on the head and crest on the tail.

They are good at climbing or running depending on the species, allowing them to escape danger quickly. Some species are excellent climbers, as they are capable of anchoring even though the material is totally solid, such as a concrete wall.

Sight is essential for locating prey and for communicating with other individuals. This sense is so refined that some species have very sharp color vision.

Some species may contain poison, such as Gila monster (Heloderma) and the chaquirado lizard (Heloderma horridum). Both species attack humans only when provoked and deaths are very rare. The most harmless species are geckos, although for many indigenous cultures they are considered highly poisonous, it is not clear why this is believed but it is thought that it is due to nocturnal activity, elliptical pupils, together with the ability to climb on solid vertical smooth surfaces could make them seem supernatural to some cultures.

Their various modes of reproduction, their ability to regulate body temperature, and the ability to regenerate broken tails in some species are highly valued as research individuals in biological science.

Water is not a problem for them. All excrete uric acid and therefore do not need to drink large amounts of liquid to get rid of nitrogenous waste. Insectivorous species obtain most of their water by consuming their prey and herbivores have saline glands for the excretion of mineral salts. They consume less water than a bird or a mammal. This explains why they are so successful in colonizing oceanic islands or extreme deserts.

Temperature

For the lizard, temperature is very important. Like fish and amphibians, they are ectothermic, that is, they receive heat from their environment. The term cold blood, although it is commonly applied, is a wrong term, because the blood is not that cold, unless the lizard is cold. The blood is usually warm, often higher than that of mammals, but these are not acceptable temperatures for them. Most species seek a temperature that ranges between 28 - 38º, called "preferred temperatures."

Most species prefer ecosystems that are scrubby, as they need to obtain heat. Normally, a diurnal lizard basks in the sun at dawn, orienting the body to maximize sun exposure until the species-preferred temperature is reached. Some species can warm above air temperature, such as the small lizard of the species various forms of Liolaemus that lives in the Andes, which raises its body temperature to 35 ° C, while that of the air oscillates around 10 ° C.

Preferred body temperature plays an important critical physiological role. All physiological processes depend on temperature and this influences behavior. The ability to perform various behaviors or function well metabolically depends on a small range of temperatures. To maximize performance, they should be kept within that temperature range for as long as possible.

Behavior

Being reptiles they are cold-blooded animals they need to spend the day in the sun to warm their blood. Most species are diurnal, when they can use their watery binocular vision. However, there are many group species within the Gekkonidae family that are most active from dusk to dawn.

To communicate better, they regularly use body language. They use specific postures, gestures and movements to define their territory, resolve any disputes, and attract their peers. However, geckos are very vocal and communicate through sound, while the rest of the species are silent.

The komodo dragon is the world's largest lizard
The komodo dragon is the world's largest lizard

Territory

Many species defend certain areas against intruders of the same or related species. Territorial defense does not always end in actual combat, the vast majority of the time they are replaced by elaborate displays and rituals that involve increasing size, erecting ridges, and various postures. Other species display bright colors alongside stereotypical movements such as push-ups, head bobbing, and tail waving.

Large, colorful horns and other forms of ornamentation are worn by males, but some species of females also defend their territories using stereotypical movements similar to those of males.

Territories are often limited to resources (such as nesting sites, food, and shelter for predators). The male who owns a territory will attract more females. Displays used by males in establishing territories can also function for courtship of females.

The social systems of indigenous lizards are fundamentally different. Instead of visual displays, chemical communication between individuals is used. Some species (such as those in the Teiidae, Varanidae, and Helodermatidae families) have deeply forked tongues and may be able to use them to determine the direction of chemical signals in a manner similar to that of snakes.

Habitat

The lizard occupies different habitats depending on the species. Some prefer burrows or burrows underground and others shallow and raised vegetation.

Some species move slowly, while others can run quickly through the desert sands.

No existing species is marine, but in the past there was an extinct group called Mosasauridae that were strictly marine. They are currently partially aquatic.

Distribution

Lizards are distributed throughout the planet, excluding the extreme north and Antarctica, and also some islands. They can be found at elevations of up to 5.000 meters high.

Food

The lizard is usually presented as an insectivorous animal, therefore carnivore, but many also eat small vertebrates and even plant matter. Some species of lizards are strict herbivores. Desert-dwelling species eat a large number of insects and invertebrates. Semi-aquatic species feed on freshwater organisms.

They spend a large part of their time obtaining food. The hunting method usually changes according to the species. For example, iguanas, anoles, agamas, chameleons ... they tend to remain immobile to wait for their prey. When they detect it, through vision, they run to where their prey is and capture it using their tongues in a process known as tongue grip. Chameleons are the most extreme example as with their long sticky tongue, they don't even have to move where they settle. However, some species actively search for their prey by probing and burrowing. They do not use their tongues to capture their prey, but they are grabbed by the jaws. In this case the tongue is free as an organ of chemoreption. Salmanquesas are of this type, but they use olfaction rather than chemoreption to detect their prey.

Predators

The lizard has many native predators that vary by habitat or species. Many of these animals are birds, mammals, invertebrates, and other reptiles.

To survive each species has a certain strategy or ability to escape. For example, chacahualas (Sauromalus) stay close to rocks and when needed they will hide between the cracks and swell the body to make it difficult to remove. He armadillo lizard (Ouroborus cataphractus) holds the tail in its mouth with its forelegs, making a spiny cylinder that is not pleasant for attackers. He King's chlamydosaurus or ruff lizard (Chlamydosaurus kingii) extends a throat strip that frames its neck and head to intimidate predators. The best known defense is the ability to self-taint. This tail will twist and distract the predator, giving the lizard time to sneak off in search of safety.

Reproduction

The lizard follows a common pattern. The male grasps the female by the skin, often by the neck or the wing of the head, and places the front and rear legs on her body. Then he pushes his tail under hers and twists his body to draw the sewers together. A hemipenis is then turned and inserted into the female's cloaca. Depending on the species, copulation can last from a few seconds to 15 minutes or more.

Most species lay eggs. In small species the number of eggs is quite uniform. The size of the clutch varies with the size, age and condition of the mother.

A common clutch can have 4-8 eggs, but larger species like the iguana can lay 50 or more eggs. The eggs are usually leathery and porous, they can expand by means of humidity as the embryo grows. The exception is the gecko whose eggs have shells that harden shortly after being laid and do not undergo any change in size or shape. Some species do not lay eggs and give birth to live young. Most of the species live in tropical climates.

The care of the young is minimal after the deposition of the eggs, but there are exceptions. Many species bury their eggs in dirt / sand and others hide them under leaf beds or in cave crevices or crevices. However the five line skink (Plestiodon fasciatus) incubates the eggs, about six weeks, and they leave the clutch infrequently to feed.

As soon as the young leave the nest, family ties are broken. However, in Australia they remain around the mother for a long period. This behavior makes them obtain greater survival. The female is able to recognize her offspring based on chemical signals.

Some species of Gekkonidae lay their eggs in common clutches, that is, several females lay their eggs in the same nest. It also seems that the same female returns to the same place to continue laying eggs.

The young do not go through any type of larval stage or any stage that depends on the adults. They differ in body color or pattern and in certain body proportions. For example, in some young species the heads are larger than in adults. The tails are usually bright blue, orange or red in color and will change color when they reach sexual maturity.

State of conservation

Most species of lizards do not have problems, but some species are classified as vulnerable due to the alteration of their natural habitats.

Relationship with humans

Most lizards are harmless to humans, with the exception of the Komodo dragon (Varanus komodoensis) which is the largest species in the world. This species stalks, attacks, and kills humans who stand in its way.

Some species possess a poisonous bite, although none are so toxic as to actually harm a human. If a human receives a bite, it will be a painful and unpleasant one, which will be caused by the jaw of the lizard and not the poison itself.

They also have an important role in human ecology that is often poorly understood. Some species are sources of food, clothing, or pest control agents. Others are pests. In Mexico, Central America and South America, iguanas are a source of food. Others are used to create leather, which is a key factor in the local economy of certain rural areas in Third World countries.

Large predatory lizards (such as monitors and tegus) can be pests, feeding on domestic farm animals or stealing eggs. These actions affect ranchers and farmers economically.

Smaller species, such as geckos, have colonized islands, cities, and towns around the world by canoeing in human boats. For example, throughout Brazil the tropical home gecko (Hemidactylus mabouia) are so common in households they know more about it (based on observation) than about other endemic species.

They do not usually carry disease and pose little danger to humans who take proper precautions to handle them. They are usually infected with some parasites, such as malaria, but they tend to be species specific. They can infect a human with salmonella, tuberculosis and other viral infections, but to become infected, the lizard must be placed inside the human's mouth.

Some species are considered pets by certain humans. As the green Iguana (Iguana iguana), dragones barbudos (Drive vitticeps), iguanas, anoles, and geckos.

Green iguanas are eaten by humans in Central America, where they are known as "chicken of the tree" for their supposed chicken flavor and the custom of perching in trees. While in Africa spiny-tailed lizards are eaten.

Popular culture

Lizards appear in many cultures around the world. Both in myths, folk tales, literature and movies.

In Australian Aboriginal mythology, there is a lizard god named Tarrotro who divided the human race into men and women, and endowed them with the ability of art. A lizard king named Mo'o appears in Hawaii and other Polynesian cultures.

In many cultures they are given supernatural powers, such as resurrection. This may be due to their regular skin shedding. In Christianity there are lizard chandeliers that are probably due to the same symbolism. In Egypt, according to Jack Trsidder, they were beneficial emblems, linked to wisdom. In African, Aboriginal and Melanesian folklore they are linked to cultural heroes or ancestral figures.

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