Who belongs to the list of reptiles. Detachments of modern reptiles: representatives, brief description, signs and photos. Description of individual species

The class of vertebrates that occupy an intermediate position between amphibians and mammals is called reptiles (reptiles). They have a greater resemblance to birds. This class includes the following animals on the list:

• crocodiles;
• turtles;
• snakes;
• lizards;
• dinosaurs (fossil form of animals of the Mesozoic era).

General characteristics of reptiles

Like amphibians, reptiles are cold-blooded creatures. In other words, their body temperature is determined by the surrounding space. To some extent, reptiles are able to regulate their temperature by covering themselves from hypothermia. For example, in the winter season, animals hibernate, and during periods of intense heat, they begin to hunt at night.

Reptiles have hard skin covered with scales. The main task of which is to protect the body from drying out. For example, in turtles the upper protection is provided by a strong shell, crocodiles have hard plates of bone origin on their heads and backs.

Reptiles breathe only through the lungs. In some animal species, the lungs are the same size and equally developed, while in others, such as snakes and lizards, the right lung is larger and is located throughout the body cavity. Turtles have fixed ribs due to the shell, so the ventilation of the body is organized in a different way. Air enters the lungs with the swinging movements of the front legs or with intensive swallowing.

The bone skeleton of reptiles is well developed. The number and shape of the ribs depends on the specific species, but all representatives of the class have them. Almost all turtles have fused bone plates of the shell and spine. snakes have ribs designed for active crawling. In lizards, the ribs serve to support fan-shaped membranes for planning in the air.

Most reptiles have a short tongue that cannot protrude. Snakes and lizards have a long tongue, divided in two, which is able to protrude far from the mouth. For this animal species, these are the most important sense organs.

To protect against the environment, small reptiles have an original coloration. Turtles are protected by a dense shell. Some snakes are venomous.

In terms of reproductive organs, reptiles have similarities with birds. As a rule, reptiles are egg-laying animals. But in some species, until hatching, the eggs remain inside at the site of the oviduct. This type includes some species of lizards and vipers.

Classification of reptiles and their distribution

Modern reptiles are divided into four divisions:

• turtles (about 300 species);
• crocodiles (25 species);
• scaly (about 5500 species of lizards and snakes);
• tuatara (tuatara).

The last detachment belongs to the only representative of beak-winged animals among reptiles.

reptiles distributed throughout the world. The largest number is seen in warm areas. In regions with a cold climate and a lack of woody vegetation, reptiles are practically not found. Representatives of this class live on land, in water (fresh and salty) and in the air.

ancient fossil reptiles

Reptiles have been known since the Carboniferous. They reached their largest sizes in the Permian and Triassic periods. At the same time, an increased multiplication of animals was observed, which populated all new territories. In the Mesozoic era, the dominance of reptiles was overwhelming, both on land and in water. This period is not in vain called the age of reptiles.

Turtles

Turtles are one of the most famous types of reptiles. There are both marine and land representatives of animals. The species is distributed throughout the world. Animals can also keep at home. The oldest representatives of turtles were discovered 200 million years ago. Scientists believe that they originated from a primitive species of cotilosaurs. Turtles are practically harmless animals, they are not dangerous to humans.

Animals of this species have a shell of a bone structure. Outside, it is formed by numerous individual elements of horny tissue, which are connected using plates. Lungs function perfectly for breathing of land turtles. Aquatic representatives of the class breathe with the help of the mucous membrane of the pharynx. The main feature of these animals is longevity. The average age of turtles exceeds the lifespan of any other reptile.

crocodiles

Animals are one of the most dangerous types of reptiles. The origin of crocodiles is associated with ancient reptiles, the size of which exceeded 15 meters in length. Scientists have been able to find the remains of ancient crocodiles on all continents of the globe. Modern representatives of this class have more familiar sizes. But among reptiles, they still remain the largest species.

Almost all the time crocodiles are in the water. Only the ears, nose and eyes of the animal appear on the surface. Crocodiles swim with webbed tails and paws. But at great depths, only single representatives of the class can exist - a combed species. Crocodile nests are located on land. In some cases, they also crawl out of the water to bask.

Reptiles have a strong powerful tail, and are also characterized by a high speed of movement on land. Therefore, crocodiles are extremely dangerous to humans. A sharp, unexpected throw can take people by surprise. Alligators are considered the most dangerous representatives of crocodiles.

Chameleons

This type of lizard is known to almost everyone. Reptiles are known for their unique coloration, which acts as a camouflage. The skin of an animal can change its color depending on environmental conditions. Chameleons live in trees. Some people keep these cute creatures at home.

Reptiles are quite whimsical in care. They need a spacious terrarium, which is equipped with special lamps. You will need a tree, a small pond, floor heating and excellent ventilation. Chameleons feed on insects. Therefore, the owners will also have to take care of their presence.

iguanas

Currently, there are more and more lovers of pets - iguanas. This representative of the lizards also requires special care. Iguanas must be kept in a special terrarium that can maintain a certain temperature regime. From food, domestic iguanas prefer fresh fruits and vegetables, as well as greens. With good care and the creation of optimal living conditions, lizards at home can grow quite large. Maximum iguana weight - 5 kg. Keeping such a pet at home is difficult, it will require a large financial injection, as well as significant labor costs.

Iguanas are among those rare reptile species that molt. Most reptiles experience this period in two days, while in iguanas it stretches for several weeks.

monitor lizards

There are about 70 species of monitor lizards. They live in different areas. The size of the animals is very impressive. In short-tailed monitor lizards, the length is about 20 cm, while in other representatives it is much longer (about 1 meter). Komodo species are considered the largest monitor lizards. Their dimensions reach three meters in length, and their weight is 1500 kg. No wonder these animals are called modern dinosaurs.

Monitor lizards are covered with large scales. They have strong paws with a tenacious grip and powerful long tail. The tongue of the animal is also large in size, at the end it is divided in half. Lizards can only smell with their tongues. The color of animals is dominated by gray and brown shades. Young representatives of the class are often found with spotted or striped scales. Monitor lizards live in regions with a warm climate. They are most commonly found in Australia, Africa and southern Asia. Depending on the habitat, monitor lizards are divided into two types. The first of them lives in a desert area with dry trees and shrubs. And the second is located closer to tropical forests and reservoirs. Some representatives of monitor lizards live on tree branches.

geckos

Unique representatives of reptiles that are able to stick to any surface, even the smoothest. Geckos can climb smooth glass walls, hang from ceilings, and many other interesting things. The lizard is able to stay on the surface with just one paw.

snakes

These are well-known representatives of reptiles. The main difference from other species is the shape of the body. Snakes have a long body, but do not have paired limbs, eyelids, and an external auditory meatus. Some of these characteristics are present in individual species of lizards, but collectively such characteristics are observed only in snakes.

Serpentine The body is made up of three elements:

• head;
• body;
• tail.

Some representatives have retained rudimentary forms of limbs. A large number of snake species are venomous. They have furrowed or canalized teeth that contain venom. This dangerous liquid comes from the salivary glands of the animal. All internal organs of the snake differ from standard indicators. They have an oblong shape. Animals do not have a bladder. There is in front of the eyes cornea, which was formed from fused eyelids. Diurnal snakes have transverse pupils, while nocturnal snakes have vertical pupils. Because Animals do not have an auditory canal, so only loud sounds are heard for them.

snakes

These are representatives of one of the varieties of snakes. Their main feature is that they are not poisonous. Snakes have bright scales with a large ribbed surface. Animals are common near water bodies. They feed on amphibians and fish. Sometimes snakes manage to catch a bird or a small mammal. Such snakes do not kill their prey, they swallow it whole.

If the snake sensed danger, then it pretending to be dead. And when attacked, a liquid with an extremely unpleasant odor is released from the mouth. Snakes breed on vegetable soils covered with wet moss or natural debris.

The list of modern reptiles can be continued for a very long time. All representatives of the class have certain similarities characteristic of this type of animal, as well as clear differences. Such animals are of great interest to scientists and hobbyists from all over the world. Their unique features can tell a lot.

The descendants of extinct dinosaurs are numerous reptiles. The list of reptiles includes about ten thousand species. All of them breathe with lungs, and their skin is covered with horny scales that protect it from drying out. Only on the territory of our country there are 72 species of reptiles.

The list of reptiles includes about ten thousand species.

Class characteristic

The reptile class includes a certain group of cold-blooded animals and has a number of anatomical features. The limbs are located on both sides and widely spaced. During movement, the reptile's body drags along the ground, which does not prevent it from remaining fast and agile at the moment of danger or hunting.

In prehistoric times, this species of fauna lived in the water. In the process of evolution, they switched to a terrestrial existence due to cellular light, dry body covers and internal fertilization. In the process of growth, the animal periodically sheds.

With fish and amphibians, they are united by the body's ability to regulate body temperature according to environmental conditions. In the winter season, they lose activity and hibernate. In the southern latitudes with a hot climate, many of them are nocturnal. The dense horny cover and the absence of glands in the epidermis prevent the loss of moisture.

Distribution area

Reptiles are common on all continents except Antarctica. Their populations are especially numerous in tropical and subtropical regions.

The most viable species live on the territory of the Russian Federation. The list of names of reptiles inhabiting almost all regions of our country is quite extensive. It includes:

1. - Far Eastern, Mediterranean, leathery, Caspian, European marsh, big-headed.
2. lizards- gray and Caspian gecko, motley and eared roundhead.
3. snakes- vipers, snakes, suckers and yellowbellies.

All representatives of this class, living in a temperate climate, are not large in size and prefer small areas for living, since they are incapable of long-distance migrations. They are characterized by high fertility. Females lay dozens of eggs. The density of livestock per hectare can reach one hundred and twenty individuals. Features of nutrition play an important role in the biological indication of nature.

Reproduction features

Reptiles breed on the land surface. Even those who spend most of their lives in the water leave their usual habitat. The mating season is accompanied by increased activity and duels of males. This is especially common in lizards and turtles.

The bulk of reptiles are egg-laying reptiles. In some species, the egg remains in the oviduct until the baby is fully mature. Such animals are ovoviviparous representatives of the fauna.

Description of individual species

Reptiles are naturally endowed with a high ability to survive and preserve the species. In the wild, there are both herbivorous and predatory reptiles. The list of titles includes:

• turtles;
• crocodiles;
• lizards;
• snake.

Turtles number about three hundred species. Distributed throughout the world. These harmless animals are often kept as pets. They are among the longest living reptiles. Under favorable conditions, they live up to two hundred and fifty years.

A strong shell protects them from predators, and body weight and size depend on belonging to a particular genus and habitat. Sea turtles can weigh up to a ton and have impressive dimensions. Among land species, there are tiny specimens weighing 125 grams and a shell length of 10 centimeters.

The head of the animal is small, which makes it possible in case of danger to quickly remove it under the shell. The reptile has four limbs. The paws of land animals are adapted for digging soil; in marine life, they have turned into flippers.

crocodiles- the most dangerous reptiles. The names of some species correspond to their habitat. The most famous of them:

• marine or combed;
• Cuban;
• Mississippian;
• Philippine;
• Chinese;
• Paraguayan.

Crocodiles are divided into families of gharials, caimans and alligators. They differ from each other in the shape of the jaws and body size.

lizards- quick representatives of the fauna. Most of them are small in size and have a high regenerative capacity. They inhabit different parts of the world, are well adapted to different climatic latitudes.

The main part of the lizards is small and has a high regenerative capacity.

The largest representative of the genus of lizards - komodo dragon. It is named after the island of the same name on which it lives. Outwardly, it resembles a cross between a dragon and a crocodile. They create a deceptive impression with their sluggishness. However, they are excellent runners and swimmers.

Snakes are included in the list of animal reptiles that are devoid of limbs. Due to the elongated shape of the body, the internal organs acquired an identical structure. More than three hundred pairs of ribs located throughout the body help to make flexible movements. The triangular head allows the snake to swallow its prey whole.

In nature, there are a huge number of different snakes. Most of them are poisonous. The poison of some is able to kill within a few minutes. Scientists have long learned to use snake venom as medicines and antidotes.

Snakes lacking venom glands include common snakes and pythons. The largest snake in the world lives on the banks of the Amazon and is called the anaconda. Kills the victim with the help of powerful muscles, wrapping rings around it.

Due to the pressure of water, sea snakes are deprived of a rounded shape and resemble a wriggling ribbon. They are very dangerous to humans, as they produce a highly toxic poison. Once on land, they die within a few hours. Settle in the mouths of rivers flowing into the sea. They rarely swim far from the shore.

Difference from amphibians

Compared to amphibians, reptiles are better adapted to living on land. Their muscles are well differentiated. This explains their ability to make quick and varied movements.

The digestive system is longer. The jaws are equipped with sharp teeth that help to chew even the toughest food. The blood supply is mixed, in which arterial blood predominates. Therefore, they have a higher metabolic rate.

Compared to amphibians, reptiles are better adapted to life on land.

The size of the brain relative to the body is larger than that of amphibians. Features of behavior and sense organs are perfectly adapted to life on the surface of the earth.

Unique reptiles

Among the most interesting and rare reptiles, there are those who have anatomical features unlike other species. The most remarkable representative of the unique fauna is Tuatara. It lives only in one place - New Zealand. With an outward resemblance to a lizard, it does not belong to the genus of these reptiles. The internal organs are similar to snakes.

With an outward resemblance to a lizard, the hatteria does not belong to the genus of these reptiles.

Unlike other animals, it has three eyes, and an additional organ of vision is located in the back of the head. Possessing slow breathing, she is able not to breathe for a minute. The length of the body is half a meter, the weight is about one kilogram.

Reptiles cause a rather ambiguous reaction in humans. Incredibly strong, dangerous and at the same time cute, these dinosaur peers have become the best example of animal adaptation to the environment. Ten reptiles from our list deserve special attention.

10. Agama Mwanza - the real spider-man of the world of reptiles

The red-headed rocky agama is considered one of the most colorful reptiles on the planet. During the hot time of the day, the males of this lizard are painted in bright red and blue colors, and the presence of a rival in their territory causes the lizards to fill with more and more bright colors. The combination of blue and red colors made this lizard incredibly popular on the net, where it was immediately dubbed the Spiderman lizard. These lizards sometimes reach 40 centimeters in length. They feed on small insects and rodents that live on their territory. Agamas are the most common lizard species in Africa.

9. Marine iguana

Adaptation of animals to the environment is the key to the flourishing of the species. The process of evolution can create the most unique living organisms from the most common specimens. Marine iguanas from the Galapagos Islands are a prime example. These reptiles feed on algae and can often be seen on coastal cliffs, where they "graze" like normal land mammals. Iguana coloring includes a wide range of colors, from brown to pinkish green. These are the only sea lizards on the planet that are a unique example of adaptation to their habitat. Marine iguanas swim like crocodiles, and with razor-sharp teeth, they tear off algae from coastal rocks.

8. Gavial


The adaptation process often involves adjusting to a new diet and takes a long time. Although crocodiles and alligators do not suffer much from food shortages, taking advantage of brute strength and powerful jaws, one species of this family has developed more advanced tactics. Reaching 6 meters in length, the gharial, although it looks menacing, does not pose any threat to people. Using narrow and long jaws, the gharial has become an excellent fish hunter, leaving larger prey to his fellows. A slightly creepy look seems to suggest that these crocodiles love to hide under water, exposing only their nose and eyes to the outside. Unfortunately, at the moment, gharials are under the threat of destruction, due to the almost complete destruction of their habitat.

7 Rhino Viper


Vipers are considered one of the most effective and dangerous predators on our planet. Although these venomous snakes feed exclusively on small prey, human activities can cause their aggressive behavior. Rhinoceros vipers stand out from the rest of the species due to their unique appearance, their scales look like a real patchwork of different colors. The so-called horns protruding above the head give a special exoticism to its appearance. Such a variegated coloration is the result of adaptation of this reptile, allowing for more effective camouflage. A little over a meter long, this snake is capable of causing you quite a few problems with its venom.

6. Rubber snake


You might think that Canada is not a place for boas, but you are wrong. In British Columbia, there is a small boa constrictor called a rubber snake. These snakes have a unique ability among reptiles - they can control their body temperature. Despite the fact that the snake reaches a length of only 45 centimeters, its external resemblance to typical boas is simply amazing. The rubber snake can live up to 70 years in a wide variety of habitats. It is often called a two-headed snake due to the special hunting method of these reptiles. She uses her tail as bait or as a distraction. Often, numerous scars from mouse bites can be found on the tails of these snakes - this is how they distract adults from the nests. While the mouse is trying to overcome the snake's tail, the boa constrictor is already feasting on mice.

5. Javanese xenoderm


This snake, also known as the dragon snake, is a rare nocturnal snake that feeds exclusively on frogs. The reptile itself is black, long and easily distinguished from the rest by several rows of unusually widely spaced scales. This is a primitive species of snake, adorned with a unique set of scales of different types - from spiked to lamellar. The snake lives in Thailand, Burma and Indonesia.

4. Turtle mata-mata


Most turtles are fairly harmless creatures, but mata mata is an exception to this rule. This species lives in the Amazon. The unique snake-like neck allows this turtle to attack birds, reptiles, invertebrates and fish that have the misfortune to be near it. To date, we do not know of cases of attacks by this reptile on humans, but we do not recommend tempting fate.

3 African Egg Snakes


Snakes are renowned for their aggressiveness and fast-paced attacks, but this species takes a much more leisurely approach to feeding. Specializing in plundering bird nests, these snakes are capable of swallowing an egg whole. The absence of traditional teeth, as we are used to seeing them, is compensated by the special structure of the cervical vertebrae. Their lower sections have special elongated processes that protrude from the walls of the esophagus. They easily open the egg shell, allowing the snake to get the precious contents.

2 Legless Lizards


It happens that many things are not what they seem at first glance. Looking at a legless lizard for the first time, you would immediately mistake it for a snake. But these lizards actually do not need limbs, they are excellent hunters and move with serpentine movements. They differ from snakes in the structure of the jaws, the presence of movable eyelids and the shoulder girdle. European legless lizards feed mainly on snails and often wipe their noses on the ground to get rid of mucus.

1. Chinese trionics


How can a turtle be without a shell? As elsewhere, in our case there are exceptions. The Chinese trionyx boasts of the absence of a shell, as such. Instead, it has globular, leathery growths on its back. These turtles reach a length of just over 30 centimeters and feed on a variety of prey. One of their distinguishing features is urination through the mouth. This process occurs when the turtle is immersed in water. Thus, it controls the amount of fluid in the body and prevents the accumulation of large amounts of salts, which is important for marine life.

Reptiles are true land animals that breed on land. They live in countries with a hot climate, and as they move away from the tropics, their number noticeably decreases. The limiting factor in their distribution is temperature, as these cold-blooded animals are active only in warm weather, in cold and hot weather they burrow, hide in shelters, or fall into a torpor.

In biocenoses, the number of reptiles is small and therefore their role is hardly noticeable, especially since they are not always active.

Reptiles feed on animal food: lizards - insects, molluscs, amphibians, snakes eat many rodents, insects, but at the same time they pose a danger to domestic animals and humans. Herbivorous land turtles cause damage to gardens and orchards, aquatic turtles feed on fish and invertebrates.

The meat of many reptiles is used as food (snakes, turtles, large lizards). Crocodiles, turtles and snakes are exterminated for the sake of the skin and horny shell, and therefore the number of these ancient animals has been greatly reduced. There are crocodile farms in the USA and Cuba.

The Red Book of the USSR includes 35 species of reptiles.

About 6300 species of reptiles are known, which are much more widespread on the globe than amphibians. Reptiles live mainly on land. Warm and moderately humid regions are most favorable for them, many species live in deserts and semi-deserts, but only a very few penetrate into high latitudes.

Reptiles (Reptilia) are the first terrestrial vertebrates, but there are some species that live in the water. These are secondary aquatic reptiles, i.e. their ancestors moved from a terrestrial way of life to an aquatic one. Of the reptiles, venomous snakes are of medical interest.

Reptiles, together with birds and mammals, make up the superclass of higher vertebrates - amniotes. All amniotes are true terrestrial vertebrates. Thanks to the embryonic membranes that have appeared, they are not associated with water in their development, and as a result of the progressive development of the lungs, adult forms can live on land in any conditions.

Reptile eggs are large, rich in yolk and protein, covered with a dense parchment-like shell, develop on land or in the mother's oviducts. The water larva is absent. A young animal hatched from an egg differs from adults only in size.

Class characteristic

Reptiles are included in the main trunk of the evolution of vertebrates, since they are the ancestors of birds and mammals. Reptiles appeared at the end of the Carboniferous period, approximately 200 million years BC, when the climate became dry, and in some places even hot. This created favorable conditions for the development of reptiles, which turned out to be more adapted to living on land than amphibians.

A number of features contributed to the advantage of reptiles in competition with amphibians and their biological progress. These should include:

• a shell around the embryo (including the amnion) and a strong shell (shell) around the egg, protecting it from drying out and damage, which made it possible to reproduce and develop on land;
• further development of the five-fingered limb;
• improvement of the structure of the circulatory system;
• progressive development of the respiratory system;
• appearance of the cerebral cortex.

The development of horny scales on the surface of the body, which protected against adverse environmental influences, primarily from the drying effect of air, was also important.

reptile body divided into head, neck, torso, tail and limbs (absent in snakes). Dry skin is covered with horny scales and scutes.

Skeleton. The spinal column is divided into five sections: cervical, thoracic, lumbar, sacral and caudal. Skull bony, occipital condyle one. In the cervical spine there is an atlas and an epistrophy, due to which the head of the reptiles is very mobile. Limbs end with 5 fingers with claws.

musculature. It is much better developed than in amphibians.

Digestive system. The mouth leads to the oral cavity, equipped with a tongue and teeth, but the teeth are still primitive, of the same type, they serve only to capture and hold prey. The digestive tract consists of the esophagus, stomach and intestines. On the border of the large and small intestines is the rudiment of the caecum. The intestine ends with a cloaca. Developed digestive glands (pancreas and liver).

Respiratory system. In reptiles, the respiratory tract is differentiated. The long trachea branches into two bronchi. The bronchi enter the lungs, which look like cellular thin-walled bags with a large number of internal partitions. The increase in the respiratory surface of the lungs in reptiles is associated with the absence of skin respiration. Breathing is only lung. The breathing mechanism of the suction type (breathing occurs by changing the volume of the chest), more advanced than that of amphibians. Conductive airways (larynx, trachea, bronchi) are developed.

excretory system. Represented by secondary kidneys and ureters that flow into the cloaca. It also opens the bladder.

Circulatory system. There are two circles of blood circulation, but they are not completely separated from each other, due to which the blood is partially mixed. The heart is three-chambered (in crocodiles, the heart is four-chambered), but consists of two atria and one ventricle, the ventricle is divided by an incomplete septum. The large and small circles of blood circulation are not completely separated, but the venous and arterial flows are more strongly separated, so the body of reptiles is supplied with more oxygenated blood. Separation of flows occurs due to the septum at the time of contraction of the heart. When the ventricle contracts, its incomplete septum, attached to the abdominal wall, reaches the dorsal wall and separates the right and left halves. The right half of the ventricle is venous; the pulmonary artery departs from it, the left aortic arch begins above the septum, carrying mixed blood: the left part of the ventricle is arterial: the right aortic arch originates from it. Converging under the spine, they merge into an unpaired dorsal aorta.

The right atrium receives venous blood from all organs of the body, and the left atrium receives arterial blood from the lungs. From the left half of the ventricle, arterial blood enters the vessels of the brain and anterior part of the body, from the right half of the venous blood goes to the pulmonary artery and then to the lungs. Mixed blood from both halves of the ventricle enters the trunk region.

Endocrine system. Reptiles have all the endocrine glands typical of higher vertebrates: the pituitary, adrenals, thyroid, etc.

Nervous system. The brain of reptiles differs from the brain of amphibians in the large development of the hemispheres. The medulla oblongata forms a sharp bend, characteristic of all amniotes. The parietal organ in some reptiles functions as a third eye. The rudiment of the cerebral cortex appears for the first time. There are 12 pairs of cranial nerves that emerge from the brain.

The sense organs are more complex. The lens in the eyes can not only mix, but also change its curvature. In lizards, the eyelids are movable; in snakes, the transparent eyelids are fused. In the organs of smell, part of the nasopharyngeal passage is divided into olfactory and respiratory sections. The internal nostrils open closer to the pharynx, so reptiles can breathe freely when they have food in their mouths.

reproduction. Reptiles have separate sexes. Sexual dimorphism is pronounced. Sex glands are paired. Like all amniotes, reptiles are characterized by internal insemination. Some of them are oviparous, others are ovoviviparous (that is, a cub immediately emerges from a laid egg). Body temperature is not constant and depends on the ambient temperature.

Systematics. Modern reptiles are divided into four subclasses:

1. lizards (Prosauria). The first lizards are represented by a single species - the hatteria (Sphenodon punctatus), which is one of the most primitive reptiles. The tuatara lives on the islands of New Zealand.
2. scaly (Squamata). This is the only relatively large group of reptiles (about 4000 species). The scaly ones are
   • lizards. Most species of lizards are found in the tropics. This order includes agamas, poisonous lizards, monitor lizards, real lizards, etc. Lizards are characterized by well-developed five-fingered limbs, movable eyelids and eardrums [show] .

     The structure and reproduction of the lizard

     quick lizard. The body is 15-20 cm long on the outside covered with dry skin with horny scales that form quadrangular scutes on the abdomen. The hard cover interferes with the uniform growth of the animal, the change of the horny cover occurs by molting. In this case, the animal sheds the upper stratum corneum of the scales and forms a new one. The lizard molts four to five times during the summer. At the ends of the fingers, the horny cover forms claws. The lizard lives mainly in dry sunny places in the steppes, sparse forests, shrubs, gardens, on the slopes of hills, railway and highway embankments. Lizards live in pairs in minks, where they hibernate. They feed on insects, spiders, mollusks, worms, eat many pests of agricultural crops.

     In May-June, the female lays 6 to 16 eggs in a shallow hole or burrow. The eggs are covered with a soft fibrous leathery shell that protects them from drying out. The eggs have a lot of yolk, the protein shell is poorly developed. All development of the embryo takes place in the egg; after 50-60 days, a young lizard hatches.

     In our latitudes, lizards are often found: agile, viviparous and green. All of them belong to the family of real lizards of the scaly order. The agama family belongs to the same order (steppe agama and roundheads - inhabitants of the deserts and semi-deserts of Kazakhstan and Central Asia). The scaly ones also include chameleons that live in the forests of Africa, Madagascar, India; one species lives in southern Spain.

   • chameleons
   • snakes [show]

     The structure of snakes

     Snakes also belong to the scaly order. These are legless reptiles (some retain only the rudiments of the pelvis and hind limbs), adapted to crawling on their belly. Their neck is not expressed, the body is divided into head, trunk and tail. The spine, which has up to 400 vertebrae, has great flexibility due to additional joints. It is not divided into departments; almost every vertebra bears a pair of ribs. In this case, the chest is not closed; the sternum of the girdle and limbs are atrophied. Only a few snakes have preserved a vestige of the pelvis.

     The bones of the facial part of the skull are movably connected, the right and left parts of the lower jaw are connected by very well stretchable elastic ligaments, just as the lower jaw is suspended from the skull by stretchable ligaments. Therefore, snakes can swallow large prey, even larger than a snake's head. Many snakes have two sharp, thin, poisonous teeth bent back, sitting on the upper jaws; they serve to bite, detain prey and push it into the esophagus. Poisonous snakes have a longitudinal groove or duct in the tooth, through which the poison flows into the wound when bitten. The poison is produced in altered salivary glands.

     Some snakes have developed special organs of thermal sense - thermoreceptors and thermolocators, which allows them to find warm-blooded animals in the dark and in burrows. The tympanic cavity and membrane are atrophied. Eyes without eyelids, hidden under transparent skin. The skin of the snake becomes keratinized from the surface and is periodically shed, i.e., molting occurs.

     Previously, up to 20-30% of victims died from their bites. Due to the use of special therapeutic sera, mortality has decreased to 1-2%.

3. Crocodiles (Crocodilia) are the most highly organized reptiles. They are adapted to an aquatic lifestyle, in connection with which they have swimming membranes between the fingers, valves that close the ears and nostrils, and a palatine curtain that closes the pharynx. Crocodiles live in fresh waters, come to land to sleep and lay eggs.
4. turtles (Chelonia). Turtles are covered above and below with a dense shell with horny shields. Their chest is motionless, so the limbs take part in the act of breathing. When they are drawn in, the air leaves the lungs, when they are pulled out, it enters again. Several species of turtles live in the USSR. Some species, including the Turkestan tortoise, are eaten.

The value of reptiles

Anti-snake sera are currently used for therapeutic purposes. The process of making them is as follows: horses are successively injected with small, but ever-increasing doses of snake venom. After the horse is sufficiently well immunized, blood is taken from it and a therapeutic serum is prepared. Recently, snake venom has been used for medicinal purposes. It is used for various bleeding as a hemostatic agent. It turned out that with hemophilia, it can increase blood clotting. The drug from snake venom - vipratox - reduces pain in rheumatism and neuralgia. To obtain snake venom and to study the biology of snakes, they are kept in special nurseries. Several serpentaries operate in Central Asia.

Over 2,000 species of snakes are non-venomous, many of them feed on harmful rodents and bring significant benefits to the national economy. Of the non-venomous snakes, snakes, copperheads, snakes, and steppe boas are common. Water snakes sometimes eat juvenile fish in pond farms.

Meat, eggs and tortoise shells are very valuable, they are export items. The meat of monitor lizards, snakes, and some crocodiles is used as food. The valuable skin of crocodiles and monitor lizards is used for the manufacture of haberdashery and other products. Crocodile breeding farms have been set up in Cuba, the United States and other countries.

Scales on the skin of a lizard

The girdle of the forelimbs is similar to the girdle of amphibians, differing only in a stronger development of ossification. The forelimb of reptiles consists of the upper arm, forearm, and hand. Back - from the thigh, lower leg and foot. Claws are located on the phalanges of the limbs.

Muscular system

The brain is located inside the skull. A number of important features distinguish the brain of reptiles from the brain of amphibians. Often they talk about the so-called sauropsid type of brain, which is also inherent in birds, in contrast to the ichthyopsid type in fish and amphibians.

There are five sections of the reptile brain.

• The forebrain consists of two cerebral hemispheres, from which the olfactory lobes depart. The surface of the cerebral hemispheres is absolutely smooth. In the cerebral vault of the hemispheres, the primary vault is distinguished - the archipallium, which occupies most of the roof of the hemispheres, and the beginnings of the neopallium. The floor of the forebrain mainly consists of the striatum.
• The diencephalon is located between the forebrain and midbrain. The parietal organ is located in its upper part, and the pituitary gland is located on the lower side. The bottom of the diencephalon is occupied by the optic nerves and their decussation (chiasm).
• The midbrain is represented by two large anterior hills - visual lobes, as well as small posterior hills. The visual cortex is more developed than in amphibians.
• The cerebellum covers the anterior part of the medulla oblongata. It is larger compared to the amphibian cerebellum.
• The medulla oblongata forms a bend in the vertical plane, which is characteristic of all amniotes.

12 pairs of cranial nerves leave the brain. In the spinal cord, the division into white and gray matter is more distinct than in amphibians. Segmental spinal nerves depart from the spinal cord, forming a typical brachial and pelvic plexus. The autonomic nervous system (sympathetic and parasympathetic) is clearly expressed in the form of a chain of paired nerve ganglia.

sense organs

Reptiles have five main sense organs:

• The organ of vision - the eyes, are more complex than frogs: in the sclera there is a ring of thin bone plates; an outgrowth departs from the back wall of the eyeball - a scallop that protrudes into the vitreous body; in the ciliary body, striated muscles are developed, which allows not only to move the lens, but also to change its shape, thus focusing in the process of accommodation. The organs of vision have adaptations to work in the air. The lacrimal glands keep the eye from drying out. The outer eyelids and nictitating membrane perform a protective function. In snakes and some lizards, the eyelids fuse together to form a transparent membrane. The retina of the eye can contain both rods and cones. Nocturnal species lack cones. In most diurnal species, the range of color vision is shifted to the yellow-orange part of the spectrum. Vision is crucial among the sense organs of reptiles.
• The olfactory organ is represented by internal nostrils - choanas and vomeronasal organ. Compared to the structure of amphibians, the choanae are located closer to the pharynx, which makes it possible to breathe freely while food is in the mouth. The sense of smell is better developed than that of amphibians, allowing many lizards to find food that is under the surface of the sand at a depth of up to 6-8 cm.
• The organ of taste is the taste buds located mainly in the pharynx.
• The organ of thermal sensitivity is located on the facial fossa between the eye and nose on each side of the head. Especially developed in snakes. In pit vipers, thermolocators even make it possible to determine the direction of the source of thermal radiation.
• The hearing organ is close to the hearing organ of frogs, it contains the inner and middle ear, equipped with a tympanic membrane, an auditory bone - a stirrup and an Eustachian tube. The role of hearing in the life of reptiles is relatively small; hearing is especially weak in snakes that do not have an eardrum and perceive vibrations propagating along the ground or in water. Reptiles perceive sounds in the range of 20-6000 Hz, although most hear well only in the range of 60-200 Hz (crocodiles have 100-3000 Hz).
• The sense of touch is pronounced, especially in turtles, which can feel even a light touch on the shell.

Respiratory system

Reptiles are characterized by suction-type breathing by expanding and contracting the chest with the help of intercostal and abdominal muscles. The air that enters through the larynx enters the trachea - a long breathing tube, which at the end is divided into bronchileading to the lungs. Like amphibians, reptile lungs are sac-like, although their internal structure is much more complex. The inner walls of the lung sacs have a folded cellular structure, which significantly increases the respiratory surface.

Since the body is covered with scales, reptiles do not have skin respiration, and the lungs are the only respiratory organ.

circulatory system

The circulatory system of reptiles

Like amphibians, most reptiles have a three-chambered heartconsisting of one ventricle and two atria. The ventricle is divided by an incomplete septum into two halves: upper and lower. With this design of the heart, a gradient (difference) in the amount of oxygen in the blood is established in the slit-like space around the incomplete septum of the ventricle. After atrial contraction, arterial blood from the left atrium enters the upper half of the ventricle and displaces the venous blood that has flowed from the right side of the ventricle into the lower half. Mixed blood appears in the right side of the ventricle. When the ventricle contracts, each portion of blood rushes to the nearest opening: arterial blood from the upper half into the right aortic arch, venous blood from the lower half into the pulmonary artery, and mixed blood from the right side of the ventricle into the left aortic arch. Since it is the right aortic arch that carries blood to the brain, the brain receives the most oxygenated blood. In crocodiles, the septum completely divides the ventricle into two halves: the right - venous and left - arterial, thus forming a four-chambered heart, almost like in mammals and birds

In contrast to the common arterial trunk of amphibians, there are three independent vessels in reptiles: the pulmonary artery, and the right and left aortic arches. Each arch of the aorta curves back around the esophagus, and, converging with each other, they are connected to the unpaired dorsal aorta. The dorsal aorta stretches back, sending arteries along the way to all organs. From the right arch of the aorta, extending from the left arterial ventricle, the right and left carotid arteries branch off with a common trunk, and both subclavian arteries that carry blood to the forelimbs depart from the right arch.

A complete separation into two independent circles of blood circulation in reptiles (including crocodiles) does not occur, since venous and arterial blood are mixed in the dorsal aorta.

Like fish and amphibians, all reptiles are cold-blooded animals.

Digestive system

Due to the variety of food available for food, the digestive tract of reptiles is much more differentiated than that of amphibians.

excretory system

The kidneys of reptiles differ significantly from the kidneys of fish and amphibians, which have to solve the problem of getting rid of a constant excess of water in the body. Instead of the trunk kidneys of amphibians (mesonephros), the kidneys of reptiles (metanephros) are located in the pelvic region on the ventral side of the cloaca and on its sides. The kidneys are connected to the cloaca through the ureters.

The thin-walled stalked bladder is connected to the cloaca by a thin neck on its ventral side. In some reptiles, the bladder is underdeveloped (crocodiles, snakes, some lizards).

reproductive system

Reptiles are dioecious animals.

male reproductive system consists of a pair of testes that are located on the sides of the lumbar spine. From each testicle, a seminal canal leaves, which flows into the wolfian canal. With the advent of the trunk kidney in reptile wolfs, the canal in males acts only as a vas deferens and is completely absent in females. The Wolffian duct opens into the cloaca to form the seminal vesicle.

female reproductive system represented by the ovaries, which are suspended on the mesentery to the dorsal side of the body cavity on the sides of the spine. The oviducts (Müllerian canals) are also suspended from the mesentery. In the anterior part of the body cavity, the oviducts open with slit-like openings - funnels. The lower end of the oviducts opens into the lower part of the cloaca on its dorsal side.

Lifestyle

Development

Fertilization is internal.

Nutrition

Most reptiles are carnivores. Some (for example, agamas, iguanas) are characterized by a mixed diet. There are also almost exclusively herbivorous reptiles (land turtles).

Economic importance

The value of reptiles for humans is relatively small. The skin of crocodiles, large snakes and lizards is used in the leather industry for the manufacture of suitcases, belts, shoes, etc., however, these items are exclusive, being a luxury item. The meat of some turtles and eggs are eaten. Snake venom is used in medicine. Many snakes are useful in exterminating rodents, and lizards are insects. Some types of reptiles are kept as pets.

Poisonous snakes pose a great danger to people, especially in tropical countries. Large crocodiles are dangerous to humans, causing damage to livestock. Many turtles harm fisheries.

Origin of reptiles

The first representatives of reptiles - cotylosaurs - are known from the Middle Carboniferous. By the end of the period, animal-like reptiles appear, which in the Permian period settled almost throughout the land, becoming the dominant group among reptiles. In the Mesozoic era, the flowering of reptiles begins, among the representatives there is the greatest diversity. There is a development of sea and river reservoirs, as well as airspace. In the Mesozoic, the formation of all groups of reptiles occurs. The last group - snakes - formed in the Cretaceous.

At the end of the Cretaceous period, there is a sharp decrease in the number of reptile species. Modern science cannot yet unequivocally indicate the causes of extinction.

Classification

There is a lot of obscurity in the classification of reptiles, largely because most of them have died out. Below is one of the possible options.

• Subclass Anapsida ( Anapsida)
  • Turtles ( testudines or Chelonia)
  • †Cotylosaurs ( Cotylosauria)
  • † Seymouriomorphs ( Seymouriomorpha)
• Subclass Proganosaurus ( Proganosauria)
  • † Mesosaurus ( Mesosauria)
• Subclass Ichthyopterygia ( Ichtyopterygia)
  • †Ichthyosaurs ( Ichthyosauria)
• Subclass Synaptosaurs ( Synaptosauria or Euryapsida)
  • † Protorosaurs ( Protorosauria)
  • †Sauropterygium ( Sauropterygia)
• Subclass Lepidosaurs or scaly lizards ( Lepidosauria)
  • † Eosuchia ( Eosuchia)
  • beakheads or proboscis ( Rhynchocephalia)
  • scaly ( Squamata): lizards and snakes
• Subclass Archosaurs ( Archosauria)
  • †Thecodonts ( Thecodontia) - became extinct, gave rise to other representatives of this subclass and, possibly, birds
  • Crocodiles ( Crocodylia or crocodilia)
  • †Pterosaurs or flying lizards ( Pterosauria): pterodactyls, etc.
  • † Lizard dinosaurs ( Saurichia) - became extinct, possibly gave rise to birds
  • †Ornithischian dinosaurs ( Ornithischia)
• Subclass Animals, or synapsids, or theromorphs ( synapsida or Theromorpha) - became extinct, but gave rise to mammals.
  • † Pelycosaurs ( Pelycosauria)
  • †Therapsids ( Therapsida)