Lizard is a terrestrial cold-blooded animal, whose body is adapted to the dry land way of life. Inhabits the forests, steppes, deserts, mountains. The small elegant body of the lizard is covered on the outside with numerous horny scales, respiration is exclusively pulmonary. It moves with the help of the feet, touching the tail and the body of the earth (reptiles). Why can not a lizard breathe skin? To answer this question will help study the features of the structure and lifestyle of one of the typical representatives of the reptile class.
The lizard is quick
On sunny places, among the grass and branches, on warm stones you can meet a small elegant animal. It's a quick or ordinary lizard. The length of her slender body reaches 15-20 cm (along with the tail). Coloration - greenish-brown with black spots of different sizes. The outer layer of dry, durable skin is thickened, keratinized in the form of scales all over the trunk and scutes on the head. At the tips of the fingers there are claws, the lizard clings to the bark of trees, the stones when climbing. Scaly cover protects the body from drying and damage. Air through it does not penetrate, that's why a lizard can not breathe skin, uses only lungs. They supply the body with oxygen, which is necessary for the cells of the body to receive energy. In the warm season, the lizard sheds several times. Scales inhibit the growth of the animal, so the stratified layer exfoliates with flaps and a new one appears.
The structure of the lizard
The lizard's body wriggles and often touches the ground. This way of movement gave the name to the class of animals - reptiles, or reptiles. This group includes a squamous group, a suborder of lizards. Numerous representatives have common features that have made it possible to combine them into one group. Consider the external structure of the lizard:
- The body consists of a head, a trunk, a long tail, four limbs;
- Pointed in front, the head section turns into a short, thick neck;
- Eyes protected by the upper and lower eyelids, they are constantly moist due to a translucent blinking membrane - the third century;
- On the head there is a pair of nostrils through which air passes;
- The outer opening of the hearing organ, covered by the tympanic membrane, is behind the eyes;
- The organ of touch is a long tongue bifurcated at the end;
- Limbs consist of three sections, on the legs - five fingers, between them there are no membranes.
Features of lizards
Reptiles are complex land animals, some of which have adapted to the aquatic life. There are external features that distinguish lizards from amphibians:
- Neck between head and trunk;
- There are no swimming membranes, on the fingers of short legs - claws;
- Dry skin with horny integument;
- Third eyelid.
At night, lizards hide in burrows, under rocks or stumps, in autumn in temperate latitudes, like frogs, fall into a hibernation. In amphibians during this period, gas exchange continues through the thin veil of the body. Why can not a lizard breathe like a frog? Reptiles lost in the process of evolution the ability to gas exchange through the skin. However, the metabolism in the reptiles is slower than in birds. In the warm season, the lizard is mobile, prey for prey, it becomes sluggish when it becomes cold, and feeds less.
Breath of lizards
In the thoracic lizard body, ribs are attached to the spine, protecting the heart and lungs from damage. Air through the nasal apertures enters the oral cavity, passes into the larynx and trachea, and then into the bronchi. Light lizards are similar to respiratory bags of a frog, but have a more complex structure. When the chest is enlarged, air is sucked in, and when it contracts, it exhales. In these movements intercostal and abdominal musculature are involved. In the lungs, air fills the cells, separated by septa, densely permeated with capillaries. Why can not a lizard breathe like a frog? In amphibians, naked moist skin is an additional respiratory organ, especially necessary during hibernation. Through the covers oxygen from the air penetrates into the circulatory system, and carbon dioxide passes into the environment. The body of a reptile is covered with horny scales, in which there are no blood vessels. Therefore, there is no dermal respiration in the lizard.
Ability to regenerate
The body of the lizard bends when it crawls, clinging to the slightest irregularities of the earth or bark with the help of claws. An animal can climb the trunk of a tree, along a stony slope. In addition to the speed of movement, there is a protective color that harmonizes with the natural habitat. Some species have acquired the ability to change shades of the skin, others menacingly hiss, scaring off predators. A thick, muscular tail helps with movement and protects from attack. There is an interesting property that lizards possess. When the pursuer attacks them from behind and holds them by the tail, it easily breaks off and continues to wriggle for a while. The attacker is mesmerized by this movement, and the lizard saves in the mink or thickets of grass. Instead of the lost animal regenerates (restores) a new tail, shorter and thicker than the previous one.
Suborder of lizards
Representatives of this systematic group can be found in all climatic zones, except tundra and polar deserts. In the world there are over 5900 species, united in families. Agamines include species of lizards, leading a tree or land way of life. Some are capable of a planning flight (the Draco genus). The largest of the family of lizards are Komodo (3 m).
Representatives of the family chameleons change the color of their body. The basilisk males have frightening ridges and thorns along the back. These lizards swim well and can run on water, keeping on its surface thanks to the impacts of webbed feet. Its name was given to the family because of its similarity to the mythical monster Basilisk. Iguanas are large representatives of the suborder of lizards. Thus, the length of the iguana is 1.9-2 m. The legs of small geckos and agamas are covered with a multitude of small outgrowths that help to adhere to different surfaces, even with glass. The legless lizards are completely devoid of limbs, but they differ from the snakes by the mobile eyelids and the presence of the shoulder girdle in the skeleton.
Representatives of all families of lizards demonstrate an ideal adaptation to certain habitats. Imperfect thermoregulation, they compensate by hiding in shelters from hypothermia and overheating. Falling into hibernation, lizards avoid the winter cold, in a hot desert - pass to the night life.