The skeleton of a lizard. Internal structure of the lizard. Types and names of lizards

Lizards, being a suborder of the class of reptiles, are the most numerous of its group. These reptiles number more than 3,500 species and live on all continents except Antarctica. In this article we will consider the internal structure, skeleton, physiological features of lizards, species and names of their families.

Interesting facts about lizards

Lizards are amazing creatures, which among the rest of the fauna representatives are distinguished by several interesting facts. The first fact is the size of representatives of different populations of lizards. For example, the smallest lizard Bruckesia Mikra is only 28 mm long, while the largest representative of this group of reptiles is the Indonesian lizard, the Komodo dragon, which has a body length exceeding 3 m, weighing about one and a half centners.

The second fact that makes these reptiles popular not only among biologists, but also ordinary people, is why and how the lizard throws the tail. This ability is called autotomy and is a method of self-preservation. When a lizard escapes from a predator, it can grab its tail, which actually poses a threat to the life of a reptile. In order to save a life, some types of medium-sized lizards are able to dump their tail, which after a while grows again. To avoid large blood loss during autotomy, the tail of the lizard is equipped with a special group of muscles that cut blood vessels.

In addition to all that is listed above, lizards in nature have the quality of skillful camouflage, adapting to the color gamut of the environment. And some of them, especially the chameleon, can take the color of the neighboring object in a few moments. How does this happen? The fact is that the skin cells of a chameleon, consisting of several almost transparent layers, have special outgrowths and a pigment, which under the influence of nerve impulses can be compressed or unclenched. At the moment of shortening of the shoot, the pigment is collected into the center of the cell and becomes hardly noticeable, and when the outgrowth is unclenched, the pigment spreads throughout the cell, coloring the skin in a certain color.

Skeleton and internal structure of the lizard

The body of the lizard consists of such parts as the head, neck, trunk, tail and limbs. The body is covered externally by scales, consisting of smaller and soft horny formations in comparison with fish scales, sweat glands on the skin are absent. A characteristic feature is also a long muscular organ - a language that participates in feeling objects. The eyes of the lizard, unlike other reptiles, are provided with a movable eyelid. The musculature is more developed than in the reptiles.

The lizard's skeleton also has some features. It consists of the cervical, shoulder, lumbar and pelvic sections, which connects the spine. The skeleton of the lizard is constructed in such a way that, as it grows together, the ribs (the first five) form a closed sternum from below, which is a characteristic feature of this group of reptiles compared to the rest of the reptiles. The chest cell performs a protective function, reducing the risk of mechanical damage to the internal organs, and it can also increase in volume during the breathing process. The limbs of the lizard, like other terrestrial vertebrates, are five-toed, but unlike amphibians, they are located in a more upright position, which provides some uplift of the trunk above the ground and, as a result, a faster movement. Significant assistance in the movement and have long claws, which are equipped with the feet of a reptile. In some species, they are particularly tenacious and help their master deftly climb the trees and rocky terrain.

The skeleton of the lizard differs from other groups of terrestrial fauna representatives by the presence of only 2 vertebrae in the sacral spine. Also, the distinctive feature is the unique structure of the caudal vertebrae, namely, in the neo-layered interlayer between them, thanks to which painless tearing of the lizard's tail occurs.

What is the similarity of a lizard and a newt?

Some people confuse lizards with newts - representatives of the infraorder of tailed amphibians. What is the similarity of a lizard and a newt? Representatives of these two supraclasses are similar to each other only externally, the internal structure of newts corresponds to the anatomy of amphibians. Nevertheless, from the point of view of physiology and lizards, and newts look visually the same: a snake-like head, moving eyelids, a long trunk with five-fingered limbs on the sides and sometimes with a crest on its back, a tail capable of regeneration.

Lizard food

Lizard refers to cold-blooded animals, that is, its body temperature varies depending on the temperature of the environment, so these reptiles are most active during the day when the air is warming up most. Most of them are carnivorous lizards, the species and names of which include not one thousand individuals. The extraction of predator lizards directly depends on the size of the reptile itself. Thus, small and medium-sized individuals eat all sorts of invertebrate animals, such as insects, spiders, worms, mollusks. The victims of large lizards are small vertebrates (frogs, snakes, small birds or lizards). The exception is the Komodo monitor, which, due to its large dimensions, can afford to hunt larger game (deer, pigs and even small buffalo).

Another part of the lizards refers to herbivorous, eating leaves, shoots and other vegetation. However, there are also omnivorous species, such as the Madagascar geckos, eating along with insects and plant foods (fruits, nectar).

Classification of lizards

The variety of lizards is quite impressive and includes 6 superfamilies, divided into 37 families:

• Iguana.
• Geckos.
• Skinks.
• Verothenitseobraznye.
• Varan.
• Wormlike.

Each of these infraorders has initializing features, due to habitat conditions and the envisaged role in the trophic chain.

Iguanoid

Iguana is an infraorder with many varieties of life forms, in which not only the external, but often internal structure of the lizard differs. Among the iguanoid are such famous families of lizards as the iguanic, agama and the family of chameleons. Iguanas prefer a warm and humid climate, so their habitat is the southern part of North America, South America, as well as some tropical islands (Madagascar, Cuba, Hawaii, British Virgin Islands , etc.).

Representatives of the infraorder iguanas can be recognized by the characteristic elongated at the expense of the pleurodontic teeth of the lower jaw. Also, the distinctive feature of iguanas is the presence on the back and tail of a prickly crest, the size of which is usually greater in males. The iguana lizard's paw is equipped with 5 fingers, which are crowned with claws (in wood species the claws are considerably longer than those of land representatives). In addition, the iguana-like have protuberances on the head resembling a helmet, and throat bags, which serve as a signaling instrument for threatening, and also play a big role in mating.

The shape of the body of iguanas is mainly of two types:

1. A tall body with compressed sides, which gradually turns into a thickened tail. This form of the body is mainly found in individuals living on trees, for example in the genus Polychrus in the South American habitat.
2. The compacted body of the discoid form is found in representatives of iguanos living on the ground.

Gecko-shaped

In the infraorder of gecko-like species are the family of the Tsekopalye, Cheshuenogi and Euplefar. The main and common feature of all representatives of this infraorder is a special chromosome set and a special muscle near the ear. Most of the geckos do not have a zygomatic arch, but their tongue is thick and not bifurcated.

• The family of gecko (tenacious) lizards lives on Earth for over 50 million years. The lizard's skeleton and physiological features are adapted to dwelling around the world. They have the most extensive habitat in both hot climatic zones and in temperate latitudes. The number of species of the family is more than a thousand.
• Family Cheshuenogi is one of the legless lizards, outwardly very reminiscent of snakes. You can distinguish them from snakes by the characteristic clicking sound that they are able to publish to communicate with each other. The body, like the snakes, is long, smoothly turning into a tail, which is adapted to autotomy. The head of the lizard is covered with symmetrical scutes. The population of the Cheshuonogi consists of 7 genera and 41 species. Habitat - Australia, Guinea and nearby land territories.
• Family Euphlyphae are small lizards in length about 25 cm with motley coloring, leading nocturnal life. Carnivores, feed on insects. They live on the American, Asian and African continents.

Reticles

Representatives of the scroll-shaped lizards are common on all continents with a temperate, tropical and subtropical climate. Basically, these are land inhabitants, although there are semi-aquatic individuals, those that spend more of their life on trees. This infraorder includes the following families:

• The Skink family is one of the most numerous according to the classification structure, which includes about 130 genera and more than 1,500 species. Distributed almost throughout the world, except Antarctica. They live mainly in the tropical zone, although they are found far from the equator. The most densely populated by this family are the islands of the Pacific Ocean, southeast Asia and Africa. Scalp lizards come in different sizes, different species vary within 8-70 cm.
• The family of Lacerdida or the Real Lizards have 42 genera and 307 species. Adapted to inhabitation in various types of natural areas: steppes, forests, deserts, mountains and even in wetlands. Distributed throughout Eurasia and Africa (with the exception of Madagascar). Lacertides are lizards mostly of small and medium size, but there are also large species, such as a pearl lizard. Food - mostly carnivorous (insects, small invertebrates).
• The Teijida family (11 genera, 129 species) inhabits the South American continent and the southern part of North America. Dimensions of lizards range from 8 cm to 1.5 m. A characteristic feature is a forked tongue like that of the lizards, for which they received a second name - American lizards. Curious is the fact that in the population of some species only females enter, they lay unfertilized eggs in which only female individuals are born.
• Family Poyasohvosty (about 70 species), live in arid regions of Africa. They can be recognized by a special large scale, under which there are bone plates. A large ribbed scape covers the entire back and passes to the tail area in the form of wide rings, wrapping the tail. Lizard-girdles in length reach up to 40 cm.
• The family of the Gerrosauri inhabit the arid and semi-arid regions of Africa. They lead both terrestrial and semi-aquatic life. The chain paws allow the herrosaurs to deftly climb onto the rocks. They have a similar structure of scales with lizards of the Skinkov family and general characteristics of the internal structure with the Ordinary Lizards.
• Family Hymnophthalmides inhabit the whole of South America and the south of Central America. They belong to the number of small lizards, whose adult individuals grow to 6 cm. Hymnophthalmids live in forests and even high in the mountains, have an external resemblance to the Teijids and have about fifty genera with two hundred species.
• The family of the Night Lizards has its name because of the way of life, during the day the lizards hide, at night they go out hunting for insects and spiders. A small family (18 species) lives in arid regions in stony terrain, the length of an adult rarely exceeds 15 cm.

Verothenitseobraznye lizards

The infraorder of spindle-shaped lizards is characterized by shallow scales with underside bone plates from below. Among the spindle-shaped lizards, there are both legless species and lizards with the usual body structure with five-fingered limbs. The infraorder includes three families:

• The family of Xenosaurus differs from other families with developed limbs and heterogeneous scales. It distinguishes the presence of mobile eyelids and auditory holes. The family includes only two genera with habitat in Central America and China.
• The Veretenitic family possesses strong jaws, provided with blunted teeth. Basically, these are carnivorous lizards, which are born alive. The family has about 10 genera and 80 species that live mainly on the American continent. The size of adults varies in the region of 50-60 cm.
• The family of the Legless has only two species with a habitat in Mexico and California. They differ in the absence of extremities, auditory apertures and bone plates.

Varanoiform lizards

The Varanoid Infraorder includes one genus - Varanas - and about 70 species. Varans live in Africa, except for Madagascar, Australia and New Guinea. The largest species of lizards, Komodo Varan, is a true record holder among all species of lizards in size, its length reaches 3 meters, and weight over 120 kg. His dinner could well become a whole pig. The smallest species of lizards (Varan Short-tailed) does not exceed 28 cm in length.

Description of Varan lizard: elongated body, elongated neck, limbs in semi-directed position, tongue bifurcated. Varans - the only kind of lizards, whose skull is completely ossified, on each side there are open ears. The eyes are well developed, equipped with a circular pupil and a mobile eyelid. Scales on the back consists of small oval or round plates, on the belly plates take a rectangular shape, on the head polygonal. The powerful body ends with an equally powerful tail, which the lizards are able to defend, inflicting heavy blows on the enemy. In lizards, leading an aquatic life, the tail is used for balancing during swimming, in woody species it is quite flexible and tenacious, it helps to climb branches. Varanens differ from most other lizards by the structure of the heart (four-chambered), similar to mammals, while the heart of a lizard from other infraorders has three chambers.

By way of life, terrestrial species predominate among the lizards, but there are also those who spend a lot of time in water and on trees. The organism of the lizard is adapted to live in various biotopes, they can be found in the desert, and in moist forests and on the seashore. Most of them are predators, active in the daytime, only two species of lizards are herbivorous. The production of carnivorous lizards becomes various mollusks, insects, fish, snakes (even poisonous!), Birds, reptilian eggs, other lizards, and large lizards often become cannibals, eating their young and fragile relatives. The entire genus of lizards refers to oviparous lizards.

Varanas are important not only as a link of the trophic chain for their habitat, but also for anthropological activity. Thus, the skin of these lizards is used in the textile industry as a material for making various haberdashery and even shoes. In some states, the local population consumes meat of these animals for food. In medicine, varana blood is used to make antiseptics. Well, of course, these lizards often become inhabitants of terrariums.

Worm-like lizards

Infrastructure of worm-like lizards consists of one family, representatives of which are small, legless individuals, outwardly similar to worms. They live on the ground and lead a burrowing lifestyle. Distributed in the forest zone in Indonesia, the Philippines, India, China, New Guinea.