Class reptiles: structural features. Snake - description, species, where it lives, what it eats, photo Number of species of modern reptiles

Amphibians (amphibians). This is a small group of the most primitive terrestrial vertebrates (Fig. 87). Depending on the stage of development, most of them spend part of their lives in water. The ancestors of amphibians were lobe-finned fish who lived in fresh, drying reservoirs.

Rice. 87. Amphibians: 1 - newt; 2 - spotted salamander; 3 - proteus; 4 - axolotl (ambistoma larva); 5 - pond frog; 6 - pipa; 7 - worm

In the larval stage (tadpoles), amphibians are very similar to fish: they retain gill breathing, have fins, a two-chambered heart and one circulation. Adult forms are characterized by a three-chambered heart, two circles of blood circulation, and two pairs of limbs. The lungs appear, but they are poorly developed, so additional gas exchange occurs through the skin (see Fig. 85). Amphibians live in warm, humid places, especially common in the tropics, where climatic conditions are suitable for them.

These are dioecious animals. They are characterized by external fertilization and development in water. From the eggs of a tailless amphibian, such as a frog, a tailed larva emerges - a tadpole with long fins and branched gills. As development progresses, the forelimbs appear, then the hind limbs, and the tail begins to shorten. Branched gills disappear, and gill slits (internal gills) appear. From the anterior section of the digestive tube, the lungs are formed, and as they develop, the gills disappear. Corresponding changes occur in the circulatory, digestive and excretory systems. The tail dissolves and the young frog comes to land. In tailed amphibians, the gills are retained much longer (sometimes throughout life), the tail does not dissolve.

Amphibians feed on animal food (worms, mollusks, insects), but larvae living in water can be herbivorous.

There are three groups of amphibians: caudate(newt, salamander, ambistoma), anurans(toads, frogs), legless, or caecilians(fish snake, worm).

Tailed amphibians most primitive. They live in and near water; their limbs, as a rule, are poorly developed. Some have feathery gills that last their entire lives.

The Ambystoma axolotl larva even begins to reproduce without reaching the adult stage. The most numerous are salamanders.

Worms- a very small family. They have no limbs, their body is elongated, reminiscent of a worm or snake.

The most prosperous group is tailless amphibians. They have a short body and well-developed limbs. During the breeding season, they “sing” - they make various sounds (croak).

Reptiles (reptiles). Reptiles belong to terrestrial vertebrates. They adapted well to life on land and displaced many of their amphibian ancestors. Reptiles have a three-chambered heart. They begin to separate arterial and venous blood due to the appearance of an incomplete septum in the ventricle of the heart; better developed than amphibians nervous system: The cerebral hemispheres are much larger (see Fig. 85). The behavior of reptiles is much more complex than that of amphibians. In addition to congenital unconditional ones, they also develop conditioned reflexes. The digestive, excretory and circulatory systems open into cloaca- part of the intestine.

The body of reptiles is covered with scales. It is formed in the thickness of the skin - the epidermis - and protects the body from drying out. Some species shed their scales during the molting process (snakes, lizards). The lungs of reptiles are much larger and more voluminous than those of amphibians due to their cellularity.

Reptiles are dioecious animals. Their fertilization is internal. The female lays eggs covered with a leathery shell in the sand or in the soil in small depressions. Even aquatic life Egg development occurs on land. Some species are characterized by viviparity.

Reptiles reached their greatest prosperity in Mesozoic era, about 100-200 million years ago, which is why this era is called the era of reptiles. There was a huge number and variety of them: dinosaurs on land, ichthyosaurs in water, pterosaurs in the air. Among them were species of enormous size, as well as rather small forms, the size of a cat. Almost all of them went extinct about 70 million years ago. The cause of the extinction is still not fully understood. There are several hypotheses: a sudden sharp change in climate, the fall of a giant meteorite, etc. But all of them do not fully explain this mystery.

Currently there are four main groups: turtles, snakes, lizards and crocodiles (Fig. 88).

Rice. 88. Reptiles: 1 - steppe gecko; 2 - agama; 3 - eared roundhead; 4 - frilled lizard; 5 - gray monitor lizard; 6 - spectacled snake; 7 - rattlesnake; 8 - already

Characteristic feature turtles is the presence of a shell consisting of bony plates and covered with horny substance. Representatives of this group can live both on land and in water. Giant and elephant turtles (up to 110 cm long) are the largest of those living on land. They are common in the Galopogos Islands Pacific Ocean, in Madagascar, Indian Ocean islands.

Sea turtles are much larger (up to 5 m) and have flipper-like legs. They live in water all their lives, but lay eggs on land.

Lizards very diverse. This is the most prosperous group. These include chameleons, geckos, iguanas, agamas, roundheads, monitor lizards and true lizards. Most lizards are characterized by an elongated body, a long tail, well developed limbs. Some (yellowbellies) have lost limbs, they resemble snakes.

U snake The main feature is a long, limbless body. These are crawling animals. All snakes are predators; they swallow prey whole or strangle it, squeezing it in the coils of their bodies. Venom glands (modified salivary glands) open through a duct at the base of the poisonous tooth. Snakes include: viper, viper, cobra, python, boa constrictor, as well as snakes - non-venomous representatives of this group.

Crocodiles Of all reptiles, they are closest to mammals. Their heart can be called four-chambered, there is a bony palate, and air enters through the nostrils into the back of the mouth. In terms of the structure of the oral cavity and the position of the tongue, they are closer to mammals than to other reptiles. These are quite large tailed animals that live in water, along river banks. On land they move slowly, but they swim well. Females lay lime-shelled eggs on land in small holes. They are characterized by caring for their offspring: the female protects the clutch and takes care of the cubs.

Reptiles live mainly in warm climates: tropics, subtropics, wet and dry places: deserts, swamps, forests. Their diet is also varied: plants, insects, worms, mollusks, and large individuals eat birds and mammals. All reptiles swallow food whole. Many species feeding on pests Agriculture(insects, rodents) bring great benefits to humans. Snake venom is used to prepare many medicines. Shoes and handbags are made from the skin of snakes and crocodiles, which previously led to the mass extermination of animals. Currently, many species are protected and grown on farms and nurseries.

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§ 62. Chordates. Fish§ 64. Birds

The class of vertebrates that occupy an intermediate position between amphibians and mammals is called reptiles. They are more similar to birds. The following animals belong to this class according to the list:

crocodiles;
turtles;
snakes;
lizards;
dinosaurs ( fossil form 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 their surroundings. To some extent, reptiles are able to regulate their temperature by covering themselves against hypothermia. For example, in winter time animals hibernate during the year, and during extreme heat They begin hunting at night.

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

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

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

Most reptiles have short tongue, which cannot stick out. Snakes and lizards have a long tongue, divided in two, which can extend far from the mouth. For this species of animal these are the most important sense organs.

To protect against environment Small reptiles have original coloring. Turtles are reliably protected by a dense shell. Some snakes are poisonous.

In terms of reproductive organs, reptiles are similar to birds. As a rule, reptiles are oviparous animals. But in some species, eggs remain inside in the oviduct until hatching. This type includes some species of lizards and vipers.

Classification of reptiles and their distribution

Modern reptiles are divided into four groups:

turtles (about 300 species);
crocodiles (25 species);
scaly (about 5,500 species of lizards and snakes);
tuatara (tuatara).

The last order belongs to the only representative of beaked animals among reptiles.

Reptiles distributed throughout the world. The greatest numbers are seen in warm areas. In regions with cold climates and 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 Carboniferous period. They reached their largest sizes in the Permian and Triassic periods. At the same time, there was an increased reproduction of animals that populated more and more new territories. In the Mesozoic era, the dominance of reptiles was overwhelming, both on land and in water. It is not for nothing that this period was called the Age of Reptiles.

Turtles

To one of the most known species reptiles include turtles. There are both marine and land representatives of animals. The species is distributed throughout the world. Animals are also allowed keep at home. The most ancient representatives of turtles were discovered 200 million years ago. Scientists believe that they descended from a primitive species of cotylosaurs. Turtles are practically harmless animals, they are not dangerous to people.

Animals of this species have a shell of a bone structure. On the outside, it is formed by numerous individual elements of horny tissue, which are connected by plates. For breathing land turtles The lungs function well. Aquatic representatives of the class breathe using the mucous membrane of the pharynx. main feature these animals have longevity. Average age Turtles have a longer lifespan than any other reptile.

Crocodiles

Animals are among the most dangerous species reptiles. The origin of crocodiles is associated with ancient reptiles, the size of which exceeded 15 meters in length. Scientists were able to find the remains of ancient crocodiles on all continents globe. Modern representatives of this class have more conventional 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 the help of webbed tails and paws. But at great depths, only single representatives of the class can exist - the comb species. Crocodiles' nests are located on land. In some cases, they also crawl out of the water to warm themselves.

Reptiles have a strong, powerful tail and are also characterized by high speed travel by land. Therefore, crocodiles are extremely dangerous to humans. A sudden sudden burst can take people by surprise. Most dangerous representatives Alligators are considered crocodiles.

Chameleons

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

Reptiles are quite finicky to care for. They need a spacious terrarium, which is equipped with special lamps. You will need wood, a small pond, heated floors and excellent ventilation. Chameleons feed on insects. Therefore, the owners will also have to take care of their availability.

Iguanas

Nowadays everything appears more lovers pets - iguanas. This representative of lizards also requires special care. Iguanas must be kept in a special terrarium that can maintain a certain temperature regime. For food, domestic iguanas prefer fresh fruits and vegetables, as well as greens. At good care and creating optimal living conditions, lizards at home can grow quite large. Maximum iguana weight - 5 kg. It is difficult to keep such a pet at home; it will require a large financial investment, as well as significant labor costs.

Iguanas are one of those rare species reptiles that molt. Most reptiles experience this period in two days, but in iguanas it lasts for several weeks.

Monitor lizards

There are about 70 species of monitor lizards. They live in different territories. The size of the animals is very impressive. Short-tailed monitor lizards have a length of about 20 cm, while other representatives have a much longer length (about 1 meter). The most large monitor lizards are considered Komodo species. Their dimensions reach three meters in length, and their weight is 1500 kg. It’s not for nothing that such 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 animal's tongue is also large in size; at the end it is divided in half. Lizards can only smell with their tongue. 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 warm climate. Most common in Australia, Africa and south asia. Depending on their 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

This famous representatives reptiles. The main difference from other species is the body shape. Snakes have a long body, but do not have paired limbs, eyelids or an external auditory canal. Some of these characteristics are present in individual lizard species, but collectively such characteristics are only observed in snakes.

Zmeinoye the body consists of three elements:

head;
body;
tail.

Some representatives retained rudimentary forms of limbs. A large number of species of snakes are poisonous. They have grooved or channeled teeth that contain venom. This dangerous liquid comes from salivary glands animal. All internal organs of a snake differ from standard indicators. They have an oblong shape. Animals do not have a bladder. There is before our eyes cornea, which was formed from fused eyelids. The snakes that lead daytime look life, have a transverse pupil, and night snakes are characterized vertical arrangement pupil. Because Since animals do not have an auditory canal, they can only hear loud sounds.

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. Amphibians and fish serve as food for them. Sometimes snakes manage to catch a bird or small mammal. Such snakes do not kill their prey; they swallow it whole.

If the snake senses danger, it pretends to be dead. And when she is attacked, a liquid with extreme unpleasant smell. Snakes breed on plant soils covered with damp 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 you a lot.

The descendants of extinct dinosaurs are numerous reptiles. The list of reptiles includes about ten thousand species. They all breathe through lungs, and their skin is covered with horny scales that protect it from drying out. There are 72 species of reptiles living in our country alone.

The list of reptiles includes about ten thousand species

Class characteristics

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 in times of danger or hunting.

In prehistoric times, this type of fauna lived in water. In the process of evolution, they switched to a terrestrial existence thanks to cellular lungs, dry body coverings and internal fertilization. During the growth process, the animal sheds periodically.

What they share with fish and amphibians is the body’s ability to regulate body temperature according to environmental conditions. In winter, they lose activity and hibernate. In southern latitudes with a hot climate, many of them lead night image life. The dense stratum corneum and the absence of glands in the epidermis prevent moisture loss.

Distribution area

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

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

- Far Eastern, Mediterranean, leatherback, Caspian, European marsh, bigheaded.
Lizards- gray and Caspian gecko, motley and long-eared roundhead.
Snakes- vipers, snakes, copperheads and yellow-bellies.

Reptiles include lizards, snakes, turtles

All representatives of this class living in 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 population density on one hectare can reach one hundred and twenty individuals. Nutritional features play important role in biological indication of nature.

Features of reproduction

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

The main part of reptiles are oviparous reptiles. In some species, the egg remains in the oviduct until the baby is fully mature. Such animals belong to ovoviviparous representatives of the fauna.

Reptiles are naturally endowed with a high ability to survive and preserve the species

Description of individual species

Reptiles are naturally endowed with a high ability to survive and preserve the species. IN wildlife Both herbivores and predatory reptiles are found. The list of titles includes:

turtles;
crocodiles;
lizards;
snake.

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

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

The animal's head 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 terrestrial animals are adapted for digging soil, sea creatures they turned into flippers.

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

sea or rowing;
Cuban;
Mississippian;
Philippine;
Chinese;
Paraguayan.

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

Lizards- quick representatives of fauna. Most of them are small in size and have high regenerative ability. inhabit different corners planets are well adapted to different climatic latitudes.

The main part of lizards are small in size and have high regenerative ability.

Most big representative genus of lizards - komodo dragon . 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 clumsiness. However, they are excellent runners and swimmers.

Snakes are included in the list of reptile animals that are missing 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 make flexible movements. The triangular head allows the snake to swallow its prey whole.

There are a huge number of different snakes in nature. Most of them are poisonous. The poison can kill some within a few minutes. Scientists have long learned to use snake venom as medicine and antidotes.

Snakes that lack venomous glands include grass snakes and pythons. The most large snake in the world lives on the banks of the Amazon and is called anaconda. It kills the victim with the help of powerful muscles, wrapping it in rings.

Due to water pressure, sea snakes lack a rounded shape and resemble a writhing ribbon. They are very dangerous for humans, as they produce highly toxic poison. Once on land, they die within a few hours. They settle at 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 fast and varied movements.

The digestive system is longer. The jaws are equipped sharp teeth, helping to chew even the toughest foods. 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 living on land

The size of the brain relative to the body is larger than that of amphibians. Behavioral characteristics and sensory 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 characteristics unlike other species. anatomical features. The most remarkable representative unique fauna is Hatteria. It lives in only one place - New Zealand. At external resemblance with a lizard it does not belong to the genus of these reptiles. Internal organs similar to snakes.

Despite its external resemblance to a lizard, tuateria does not belong to the genus of these reptiles

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

This is a nocturnal predator. It feeds mainly on small animals, crawling and flying insects. The maximum life expectancy is 100 years.

The unique features of reptiles are of interest to biologists and lovers of these animals. Some species have not been fully studied due to their secretive lifestyle and remote habitats. Even the most dangerous predators to humans contribute to the ecological balance of the planet and need protection from extermination.

They explored new, drier habitats. Reptiles gained an advantage in the struggle for existence due to the emergence of adaptations to prevent the loss of water by the body and the transition to a terrestrial method of reproduction.

Having conquered the land, the ancient reptilians reached an unprecedented peak. In the Mesozoic they were represented by a huge variety of forms.

The class Reptiles, or Reptiles, is represented primarily by terrestrial animals. They reproduce and develop exclusively on land. Even those species that live in water breathe atmospheric air and go ashore to lay eggs.

The body of reptiles consists of a head, torso and tail. It is protected from drying out by the skin. Breathing is exclusively pulmonary. More complex structure circulatory system allowed reptiles to more successfully adapt to the conditions of the land-air habitat compared to amphibians. Reptiles are cold-blooded animals, their activity depends on the ambient temperature, so most species live in areas with a hot climate.

Many species of reptiles have elongated bodies, for example snakes, lizards, and crocodiles. In turtles it is round and convex. Reptiles have dry skin without glands. She's covered horny scales, or shields, and almost does not participate in gas exchange. As reptiles grow, they periodically shed their skin. Reptiles have two pairs of legs on the sides of their body. The exceptions are snakes and legless lizards. The eyes of reptiles are protected by eyelids and a nictitating membrane (third eyelid).

Respiratory system

Due to the loss of skin respiration, the lungs of reptiles are well developed and have a cellular structure. The rib cage is formed for the first time in the skeleton. It consists of the thoracic spine, ribs and sternum (absent in snakes). Volume chest can change, so reptiles breathe by sucking air into their lungs, and not swallowing it, like amphibians.

Nervous system

The brain of reptiles is larger and has a more complex structure than that of amphibians: the size of the cerebellum and cerebral hemispheres has increased. This is associated with their better coordination, mobility, and development of sensory organs, especially vision and smell.

Nutrition and excretion

Most reptiles are predators, only land and sea turtles They feed mainly on plants. The organs of excretion are the kidneys. The need to use water sparingly leads to the fact that the waste products of reptiles contain almost no water.

Circulatory system

The heart of reptiles is three-chambered: it consists of a ventricle and two atria. Unlike amphibians, in the ventricle of reptiles there is incomplete septum, dividing it in half. There are two circles of blood circulation.

In reptiles, internal fertilization is not associated with water. This gave them an advantage in the struggle for existence over amphibians, and they spread widely over land. Reptiles reproduce by laying eggs. After fertilization, the embryo is covered with egg and embryonic membranes. They provide protection and participate in the processes of nutrition and excretion.

Predatory reptiles regulate the number of their victims. Lizards and snakes, feeding on insects and rodents, benefit humans. Snake venom is used in medicine. Beautiful and valuable products are made from crocodile and snake skin.

If you meet a viper in the forest, remember that it never attacks a person first and will try to hide. You should not step on it, try to catch it or kill it. The victim of a bite should be given tea and taken to a doctor as soon as possible. Incisions, application of a tourniquet, and drinking alcohol can only harm him.

Due to barbaric destruction by humans, many species of reptiles today are on the verge of extinction, and special protective measures are required to save them.