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 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 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 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 reptile fossils

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 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. 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 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. With good care and 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 Komodo species are considered. 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

These are famous representatives of 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 snakes differ from standard indicators. They have an oblong shape. Bladder absent in animals. There is before our eyes cornea, which was formed from fused eyelids. Snakes that are diurnal have a transverse pupil, while nocturnal snakes are characterized by 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 attacked, a liquid with an extremely unpleasant odor is released from the mouth. 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 a lot.

Class reptiles: structural features

Reptiles have such interesting features, How internal fertilization, as well as egg laying who are rich nutrients and are covered with a fairly dense protective shell, which gives them the opportunity to develop on land.

In all animals belonging to the class of reptiles, the body is covered with protective formations in the form of scales, forming a continuous cover. Their skin is always dry; evaporation of moisture through it is impossible, so they can live in dry places.

Reptile breathing is carried out exclusively by the lungs, which have a more complex structure compared to the lungs of amphibians. Such breathing became possible due to the fact that reptiles had a new section of the skeleton - the chest, formed by a number of ribs, which are connected on the dorsal side to the spine, and on the abdominal side - to the sternum. Thanks to special muscles, the ribs are mobile, which promotes expansion chest, as well as the lungs during inhalation and their collapse during exhalation.

Changes in the structure of the respiratory system also affected changes in blood circulation in all animals included in the class of reptiles. Most of them have a 3-chamber heart and, like amphibians, 2 circles of blood circulation. And the structure of the heart in reptiles is more complex than in amphibians. Its ventricle has a septum, at the moment of contraction of the heart, almost completely dividing it into the right (or venous) and left (or arterial) halves.

It is this structure of the heart and the different arrangement of the main vessels than in amphibians that contributes to a stronger separation of venous and arterial flows, due to which the body of reptiles is better supplied with more oxygenated blood.

The main vessels included in the systemic and pulmonary circulation are typical for all terrestrial vertebrates. But the main difference between the pulmonary circulation of amphibians and reptiles is that the latter have lost their skin veins and arteries, and the pulmonary circulation includes exclusively pulmonary vessels.

About 8,000 are known to science existing species reptiles that live on all continents, with the exception of Antarctica. The class of reptiles includes the following orders: proto-lizards, scaly, crocodiles And turtles.

gecko

Reproduction of reptiles

In terrestrial reptiles, fertilization is internal. During the mating process, the male injects sperm into the female's cloaca, then they penetrate into the egg cells, where fertilization occurs. The eggs develop in the female’s body, and then she lays them on land, burying them in holes.

The outside of the egg is covered with a special dense shell. It contains the necessary supply of nutrients, thanks to which the development of the embryo occurs. After a while, from the eggs, not larvae emerge, as in amphibians, but individuals that are capable of independent life.

Turtle lays eggs

This order includes a real “living fossil” called tuateria(lat. Sphenodon punctatus ), which is the only species preserved off the coast of New Zealand, on small islands. This lizard-like animal is very sedentary and mainly behaves night image life. The structure of the hatteria has features that make reptiles similar to amphibians: the bodies of its vertebrae are biconcave, and a notochord is preserved between them.

Gatteriya

Squad Squamate

Scaly (lat. Squamata) are also one of the orders of the class of reptiles such as chordates. This group includes suborders: lizards, chameleons, snakes and amphisbaenids (two-walkers). The detachment received this name because the bodies of all its representatives are covered with special horny scales or scutes.

A typical representative of scaly ones is quick lizard. Her external structure indicates that it is a terrestrial animal. There are no swimming membranes on her five-fingered limbs, and her fingers are armed with short claws, thanks to which her body crawls along the surface of the earth when moving, in contact with it, i.e. creeping (hence the name).

Xamelon

Squad of crocodiles

Aquatic vertebrate crocodiles (lat. Crocodilia) - are the largest and most highly organized predatory reptiles, adapted to an aquatic lifestyle. These representatives of the reptile class live in the tropics. All crocodiles are semi-aquatic predators, feeding on aquatic, semi-aquatic and watering animals.

Turtle squad

The turtle order includes about 328 modern species, belonging to 14 families and two suborders. They are widespread in both tropical and temperate climate zones, both in water and on land.

Turtles (lat. Testudines) differ from others by a durable, well-developed shell formed from bony plates, which are covered on the outside with a horny substance. It consists of two parts: an upper convex shield and a lower flat shield. The shell of turtles serves as the main protection against enemies.

Reptiles are an unusual class that falls between amphibians and mammals. They are otherwise called reptiles. But not everyone knows what reptiles are.

Reptiles are vertebrates that share similarities with birds and mammals.

Let's take a closer look at this class.

What are reptiles?

Representatives of this class are cold-blooded creatures. Their body temperature is determined by the temperature of the environment. But they have one feature: they can regulate their temperature themselves. The ancestors of reptiles are amphibians. In winter, reptiles usually sleep. And in hot weather they are only nocturnal.

Reptiles have tough skin covered with scales.. Such skin is needed to protect the body from drying out. These animals breathe only through their lungs. Some representatives of this class have lungs of the same size, while others have one lung larger than the other. And this is the norm. The skeleton of reptiles is well developed. Everyone has ribs, but their number depends on the representative of this class.

Almost all species of this class have a tongue, but for some it is short, and for others it is very long. It is also the main sense organ. To protect themselves from enemies, these animals change color, some have a hard shell, and some are even poisonous. These animals reproduce like birds, that is, they lay eggs.

The following animals belong to the class of reptiles:

• Snakes;
• Lizards;
• Turtles;
• Dinosaurs.

Types of reptiles

Reptiles or reptiles are divided into four orders:

Reptiles can be found anywhere, but the largest number of them live in warm countries. Where it is always cold and there is little vegetation, these animals are very rare. Reptiles live everywhere. And in water, and on land, and in the air. Let's take a closer look at the representatives of this class.

Turtles

Turtles are the most famous among reptiles. They can live both on land and in water. They can be seen not only in the zoo and in wildlife, many keep them at home. These cute animals do not pose any danger to humans; they are harmless.

Turtles appeared about two hundred million years ago. These reptiles have a shell. He protects them from enemies. It consists of two parts: abdominal and dorsal. On top it is covered with horny tissue in the form of plates.

These animals come in different sizes. There are giant turtles that can reach 900 kilograms. And there are little turtles. Their weight does not exceed 125 grams, and the length of the shell is only ten centimeters.

Instead of teeth, this animal has a powerful beak. She uses it to grind food.

Based on their habitat, turtles are divided into:

• Freshwater: painted or decorated, European marsh, red-eared, caiman;
• Marine: hawksbill, leatherback, green or soup turtle;
• Ground;
• Land: elephant, Egyptian, Central Asian, leopard, Cape;

What do these animals eat?. Their food depends entirely on their habitat. Land turtles They feed on fruits, vegetables, tree branches, mushrooms and grass. And sometimes they can even eat worms and snails.

Aquatic turtles feed on small fish, shrimp, squid, frogs, snails, mollusks, insects, and bird eggs.

Land turtles who live at home eat cabbage, apples, tomatoes, beets, cucumbers, dandelions, chicken eggs. And aquatic house turtles love to eat earthworms, boiled meat, bloodworms, insects, algae and lettuce.

The turtle is a long-liver. She will outlive any other representative of reptiles.

Crocodiles

Crocodile

The crocodile is the only representative of the archosaur subclass. Their body length ranges from two to seven meters. And the mass can reach more than 700 kilograms. The crocodile is a fairly fast animal in the water. Its speed can reach forty kilometers per hour.

The number of teeth in a crocodile ranges from 70 to 100. This depends on the type of crocodile. The teeth are long and sharp, about five centimeters.

These animals live only in warm countries with a humid climate: Africa, Japan, Australia, Bali, Northern and South America, Guatemala, Philippine Islands.

Crocodile is a predator, so it feeds on fish, shellfish, birds, lizards, snakes, antelopes, deer, buffalos, wild boars, dolphins, sharks, leopards, lions, hyenas. These animals can even eat a monkey and a porcupine, a kangaroo and a bunny. And there are cases when crocodiles eat their own kind.

Crocodiles live for quite a long time - a hundred years.

Species of crocodiles

Crocodiles are divided into three families: true crocodiles, gharials and alligators.

In its turn, Crocodiles of the true family are divided into the following species:

The alligator family is divided into:

• Mississippian - differs from other species in that it can easily withstand the cold, freezing its entire body in the ice.
• Chinese - rare and a small species of alligator. Its length does not exceed two meters, and it weighs only about forty-five kilograms.
• Crocodile caiman - otherwise called the spectacled crocodile. This is due to the fact that on its face there are growths between the eyes that resemble glasses.
• Black Caiman - pretty close-up view alligator. Its length reaches 5.5 meters and it weighs more than 500 kilograms.

The gharial family is divided into:

• Gangetic gharial. The length of his body reaches six meters, and he weighs only about two hundred kilograms.
• Gavial. The muzzle of this species is narrow and long. The body length is six meters, and the weight does not exceed 200 kilograms.

Hatteria

Most people think that hatteria is lizard. But this is a mistaken opinion. This reptile lived back in the era of dinosaurs and forms the order of beaked heads. This reptile has another name - tuatara.

They live only in New Zealand. In appearance they resemble an iguana. The internal structure is similar to that of a snake. They took some from turtles, and some from crocodiles.

She has one more feature - three eyes. The third eye is located at the back of the head. The length of the hatteria reaches more than fifty centimeters, and it weighs no more than one kilogram.

This amazing animal is only nocturnal. The breathing of the hatteria is slow. She may not breathe for as long as sixty minutes.

This reptile feeds on insects, snails, and worms. Life expectancy is quite long, about a hundred years.

Lizards

Lizards belong to the class of reptiles. Their diversity is very large - about six thousand species. They all differ from each other in their size, color, and habitat.

Lizards are very similar to newts, but they have many differences. One of the main differences is that the newt is an amphibian. An amphibian is different from a reptile.

Almost all lizards have a feature- this is the ability to throw your tail into in case of emergency. Many lizards can change body color.

Lizards feed on insects: butterflies, snails, grasshoppers, spiders, worms. Major representatives They feed on small animals, snakes and frogs.

Lizards are divided into six infraorders:

• Skink-like;
• Iguanas;
• Gecko-like;
• Fusiform;
• Vermiform;
• Monitor lizards

All these infraorders are divided into families. Skinkoids are divided into:

Iguanas are divided into fourteen families. The most a prominent representative This infraorder is a chameleon.

Gecko-like are divided into seven families. Of which an unusual lizard can be distinguished is the scalepod. The peculiarity of this reptile is that it has no legs.

Fusiformes is divided into five families: earless monitor lizards, spindle lizards, legless lizards, monitor lizards, xenosaurs.

Worm-like lizards consist of one family. These reptiles are similar to earthworms.

Monitor lizards consist of several families. They are the most big lizards. For example, komodo dragon can weigh more than ninety kilograms.

Snakes

A snake is a cold-blooded animal, which belongs to the class of reptiles. The weight and size of snakes vary. Their length can reach nine meters, and their weight is more than one hundred kilograms.

Snakes can be poisonous or non-venomous. These reptiles are deaf. They navigate using language. It is he who collects information about the environment.

Snakes eat rodents, bird eggs, fish, and some even feed on their own kind. They eat food only twice a year.

Snakes are oviparous. Some people lay ten eggs, while others lay one hundred and twenty thousand eggs. Some representatives give birth to live young.

The variety of snakes is huge. There are more than three thousand species.

The most interesting representatives are the following:

Now you know what reptiles or reptiles are. And who are their representatives.

The classes Mammals and Reptiles belong to the same phylum - Chordata. Mammals, together with the class of Birds, at one time descended from reptiles, and then spread across the Earth thanks to some kind of cataclysm, which sharply reduced the number of lizards.

Mammals distributed throughout the vastness of the World Ocean, on all continents, except for the interior of Antarctica. The penetration of mammals into the airspace and deep into the soil is limited.

Mammals are vertebrates that have a number of characteristic features. Only animals and first animals feed their young with milk thanks to the mammary glands of females, only animals “engage in” viviparity. Only these animals are covered hairline, have sweat and sebaceous glands.

The mammalian skeleton consists of the axial and skull. The axial ridge is divided into the cervical thoracic, lumbar and sacral regions. Only the spine of most Beasts has 7 vertebrae in the cervical region, allowing the head to move in all planes. The number of caudal vertebrae can reach 49 pieces. The skull of mammals is distinguished by its size and special strength. This occurred as a result of fusion of the bones of the head skeleton. Only these animals have a tympanic bone at the base of the skull. All animals have 2 limb belts and a tail. Only cetaceans in this chain lose their pelvis.

The respiratory system is represented by the alveolar lungs. A special role in the process of saturating the lungs with air is played by the diaphragm, which is characteristic feature class.

The circulatory system is maximally developed - it has 2 circles of blood circulation, a four-chambered heart and highly specialized anucleate cells - red blood cells, which supply the organs with oxygen. All representatives of the class are warm-blooded.

Mammals

Nervous system highly organized. The most developed are the brain and cerebellum. All senses are present. Digestive system complex, differentiated, and all its organs are specialized. Distinctive feature animals are teeth that “sit” in special cells and have different functionality - incisors, molars.

The genitourinary system is different in females and males. Female organs completely hidden in half of the body. Animals are characterized by internal fertilization, the birth of live young or ovoviviparity - platypuses, echidnas.

Mammals are divided into 28 orders, among which there are Pinnipeds and Primates, Cetaceans and Predators, Chiropterans and Elephants, Rodents and Pangolins.

Reptiles- This is a class of vertebrates. Divided into 4 groups - Lizards, Snakes, Crocodiles and Turtles. Reigned on Earth in Mesozoic era, at the end Cretaceous period their numbers declined sharply.

Reptiles have skin that is covered with scales, but there are no glands in it. Snakes have the ability to shed their skin, peeling it off like a stocking. The number of vertebrae depends on the order and species; there can be from 50 to 435 pieces. Except for snakes, all reptiles have 2 limb girdles. The skeleton of turtles is fused with the plates of the shell.

The nervous system of reptiles is represented by the brain and spinal cord. In the first, differentiation into white and gray matter is already visible. Animals have all senses. The organ of vision is poorly developed.

The breathing process of reptiles occurs thanks to the lungs. The circulatory system has 2 circles of blood circulation, but due to the three-chambered heart and the presence of the dorsal aorta, mixed blood flows to a number of organs. Reptiles are cold-blooded animals.

The digestive system is better differentiated compared to amphibians, but primitive compared to mammals. Reproduction occurs by laying eggs or ovoviviparity.

Conclusions website

1. Different times of appearance on Earth. Reptiles formed at the end of the Paleozoic, mammals - at the end of the Mesozoic.
2. The number of orders of mammals is 7 times greater than that of reptiles.
3. The skin of reptiles is covered with scales, in mammals it is covered with hair, and there are glands in the epidermis.
4. IN respiratory system In mammals, a diaphragm appears; the lungs of reptiles are very primitive.
5. The heart of reptiles, except the crocodile, is three-chambered; mixed blood flows to the organs. Animals have a four-chambered heart, and arterial blood flows to the organs.
6. Reptiles are cold-blooded, mammals are warm-blooded.
7. Reptiles reproduce by laying eggs or ovoviviparity. Mammals, except the first animals, are viviparous.
8. Reptiles are more primitively organized. Mammals are the most highly organized creatures on Earth.

Reptiles, compared to amphibians, represent the next stage in the adaptation of vertebrates to life on land. They are the first true class of land vertebrates. They live mainly in regions with warm and hot climates. During the conquest of land, reptiles acquired a number of adaptations:

The body is divided into head, neck, torso, tail and five-fingered limbs.

The skin is dry, devoid of glands and covered with horny cover, protecting the body from drying out. The growth of the animal is accompanied by periodic molt.

Skeleton durable, ossified. The spine consists of five sections: cervical, thoracic, lumbar, sacral and caudal. The shoulder and pelvic girdles of the limbs are strengthened and connected to the axial skeleton. The ribs and chest are developed.

The musculature is more differentiated than in amphibians. Developed cervical and intercostal muscles, subcutaneous muscles. The movements of the body parts are more varied and faster.

The digestive tract is longer than that of amphibians and is more clearly differentiated into sections. Food is captured jawtami, having numerous sharp teeth. The walls of the mouth and esophagus are equipped with powerful muscles that push large portions of food into the stomach. At the border of the small and large intestines there is cecum, especially well developed in herbivorous terrestrial turtles.

Respiratory system - lungs - have a large respiratory surface due to their cellular structure. Developed airways - trachea, bronchi, in which the air is moistened and does not dry out the lungs. Ventilation of the lungs occurs by changing the volume of the chest.

Heart three-chamber, however, the ventricle has an incomplete longitudinal septum, which prevents complete mixing of arterial and venous blood. Most of the body of reptiles is supplied with mixed blood with a predominance of arterial blood, so the metabolic rate is higher than that of amphibians. However, reptiles, like fish and amphibians, are poikilothermic (cold-blooded)ny) animals, whose body temperature depends on the temperature of their habitat.

Excretory organs – pelvic kidneys. Urine flows through the ureters into the cloaca, and from it into the bladder. In it, water is additionally sucked into the blood capillaries and returned to the body, after which urine is excreted. The end product of nitrogen metabolism, excreted in the urine, is uric acid.

The brain has a larger relative size than that of amphibians. The cerebral hemispheres of the forebrain with rudiments are better developed bark and cerebellum. The forms of behavior of reptiles are more complex. Sense organs are better adapted to a terrestrial lifestyle.

10. Fertilization only internal. Reptiles lay eggs protected from drying out by a leathery or shell membrane. on the land. The embryo in the egg develops in a watery shell. Development direct.

Features of the structure and life processes .

Let's look at the structure of the main organs of reptiles using the example spinning lizards.

The lizard's body is divided into head, torso and tail. In the trunk section the neck is well defined. The entire body is covered with horny scales, and the head and belly are covered with large scutes. The limbs of the lizard are well developed and armed with five fingers with claws.

The humerus and femur bones are parallel to the surface of the ground, causing the body to sag and touch the ground (hence the name of the class). The cervical spine consists of eight vertebrae, the first of which is movably connected to both the skull and the second vertebra, which provides the head with greater freedom of movement. The vertebrae of the thoracolumbar region bear ribs, some of which are connected to the sternum, resulting in the formation of the rib cage. The sacral vertebrae provide a stronger connection to the pelvic bones than in amphibians.

In lizards, when the tail spontaneously drops (the phenomenon of autotomy), the gap occurs not between the vertebrae, but in the middle, where there are thin cartilaginous layers dividing the vertebral body into two parts.

Excretory organs are represented by pelvic kidneys, in which the total filtration area of ​​the glomeruli is small, while the length of the tubules is significant. This promotes intensive reabsorption of water filtered by the glomeruli into the blood capillaries. Consequently, the excretion of waste products in reptiles occurs with minimal water loss. In them, like in terrestrial arthropods, the end product of excretion is uric acid, which requires a small amount of water to be excreted from the body. Urine is collected through the ureters into the cloaca, and from it into the bladder, from which it is excreted as a suspension of small crystals.

Brain Reptiles, compared to those of amphibians, have a better developed cerebellum and cerebral hemispheres of the forebrain, the surface of which has the rudiments of the cortex. This causes various and more complex forms of adaptive behavior.

Sense organs more consistent with a terrestrial way of life. The eyes are protected by movable eyelids (upper and lower) and a nictitating membrane. Focusing of vision is achieved both by moving the lens relative to the retina and by changing its curvature. Some diurnal species have color vision. Lizards have a well-developed parietal eye, a light-sensitive organ located on the crown.

Rice. 41. Lizard brain: I - top; II - bottom; III - side; 1 - forebrain; 2 - striatum; 3 - midbrain; 4 - cerebellum; 5 - medulla oblongata; 6 - funnel; 6" - pituitary gland; 7 - chiasm; 8 - olfactory lobe; 9 - pineal gland.

Hearing organ consists of the middle and inner ear. The sense of smell is better developed than in amphibians.

Some species of snakes have a thermal sense organ (between the nostrils and the eye), which allows them to sense the heat emanating from their prey at a distance. This makes it possible for snakes to hunt warm-blooded animals without seeing them.

In reptiles, fertilization is internal. They reproduce by laying eggs or ovoviviparity. The eggs are relatively large and rich in nutrients, which ensures direct development of the embryo without intermediate larval stages. The eggs are protected from drying out by protective shells (leathery or shell). The embryo in the egg develops in a cavity filled with fluid, which contributes to the proper formation of its organs.

Diversity and importance of reptiles

Modern reptiles are only small remnants of a rich and diverse world of animals that inhabited not only all the land, but also all the seas of the planet in the Mesozoic era. Currently, the class Reptiles includes more than 7 thousand species, united in several orders, among which the most numerous are Scaly, Crocodiles, Turtles and Beaked.

Order Scaly ( Sguamata ) – the largest group of reptiles (approximately 6.5 thousand species). They are characterized by the presence of horny scales in their integument.

In the central zone of the CIS the sand lizard lives, the viviparous lizard is common to the north, and the southern regions are inhabited by geckos, agamas and the largest lizard - the gray monitor lizard (up to 2 m long). Thanks to its well-developed limbs, the monitor lizard runs quickly, its body raised high above the ground. Monitor lizards are widespread in Africa, South Asia, the Malay Archipelago and Australia, as well as in the sandy deserts of Turkmenistan and Uzbekistan.

Snakes are legless, scaly animals with a long cylindrical body, using the wavy curves of which they move. They do not have movable eyelids. Prey is swallowed whole thanks to a widely extensible mouth (the lower jaws are suspended on extensible ligaments). The teeth are sharp and directed backwards. When attacking a victim, poisonous snakes move forward from oral cavity teeth and with their help introduce the secretion of poisonous glands into the body of the prey. The sternum is missing. The ribs are free and extremely mobile. The middle ear is simplified, the eardrum is absent. Distributed in all parts of the world, but numerically predominant in hot countries. Non-venomous snakes are widely known - snakes, boa constrictors, and poisonous ones - viper, viper, rattlesnake, sand faff etc. Snake venom is used to prepare medicines.

Squad Crocodiles ( Crocodylia ) represented by large (up to 6 m long), the most highly organized reptiles, adapted to a semi-aquatic lifestyle. They have a lizard-like, slightly flattened body, covered with horny scutes, with a laterally compressed tail and swimming membranes between the toes of the hind legs.

Rice. 42. Crocodiles: 1 - gharial; 2 - Nile crocodile; 3 - Chinese alligator

The teeth sit in cells (like in mammals). The bases of the teeth are hollow inside, and new, replacement teeth develop in these cavities. There are multiple changes of teeth during the life of a crocodile. The lungs have a complex cellular structure and hold a large supply of air. The diaphragm is developed. The heart is four chambered.

They reproduce by laying eggs (10-100 eggs) covered with a calcareous shell. They become sexually mature at 8-10 years of age and live up to 80-100 years.

Known are the Nile crocodile (Africa), alligator (China, America), caiman (America), gharial (Hindustan, Burma). In some countries, crocodile meat is used in food, and the skin is a valuable raw material for the manufacture of haberdashery. Due to intensive fishing, the number of crocodiles has sharply decreased. Farms for their breeding have been created (USA, Cuba).

Turtle Squad ( Testudines ) unites reptiles that have a compact body enclosed in a durable bony shell into which the neck, head, limbs and tail can be retracted. The top of the bone shell is covered with horny plates or soft skin.

Rice. 43. Turtles: 1 - elephant turtle; 2 - steppe tortoise; 3 - marsh turtle; 4 - carriage; 5 - Ussuri soft-skinned turtle.

The jaws are devoid of teeth and have sharp horny edges. The vertebrae, except for the cervical and caudal sections, are fused to the dorsal part of the shell (as are the ribs). The breathing mechanism is associated with the movement of the neck and shoulders, which, moving out from under the shell, stretch the lungs. The metabolic rate is low. Capable of prolonged fasting. Live in humid tropics and in hot deserts. In many countries, turtle meat and eggs are eaten. The horny plates of some turtle species are used to make crafts. Swamp turtle - lives in weakly flowing water bodies and feeds on a variety of small aquatic and terrestrial animals.

Lives in the Galapagos Islands elephant turtle. The huge shell can be up to 110 cm long and up to 60 cm high. Thick and powerful columnar legs support the heavy body. The mass of adult specimens is about 100 kg, and individual giants weigh up to 400 kg.

The only type of modern Beakheads ( Rhynchocephalia ) – tuateria has many extremely primitive features and is preserved only in New Zealand and the surrounding islands.

Rice. 44. Hatteria.

Hatteria looks very much like a lizard with a massive body, large head and five-fingered limbs. A low ridge of triangular vertical plates stretches from the back of the head along the back and tail. The hatteria is painted in a dull olive green color, with small and larger yellow spots on the sides of the body and limbs.

The pupils of the large eyes, located on the sides of the head, are in the form of a vertical slit. The tuateria does not have eardrums; the middle ear cavity is filled with adipose tissue.

The body of adult males is up to 60 cm long, weighing 800 g. Females are almost twice as small as males. Hatteria reaches maturity only at 20 years of age. Life expectancy is also long: in captivity, tuataria lived for more than 70 years.

The main food of the tuateria is various invertebrates, especially insects, in particular beetles and large wingless grasshoppers, as well as spiders, worms, mollusks, sometimes lizards, frogs, and bird eggs. The hatteria swallows its prey whole.

The tuateria moves slowly, while hardly raising its belly above the substrate. However, when hunting or in a frightened state, it rises to its feet and moves quickly. In addition, she is a good swimmer and willingly goes into the water.

Origin of reptiles. Reptiles have been known since the end of the Carboniferous period of the Paleozoic era. They reached their heyday in the Mesozoic era, by the end of which they were replaced by birds and mammals. The ancestors of modern reptiles are considered to be primitive Devonian amphibians - stegocephalians, which gave rise to cotilosaurs - ancient reptiles.

The flourishing of ancient reptiles in the Mesozoic era was facilitated by a warm climate, an abundance of food both on land and in water, as well as a lack of competitors. They inhabited a terrestrial environment dominated by giant dinosaurs, reaching a length of 30 m. Among them were both herbivores and predators. The aquatic environment was dominated by fish-like lizards - ichthyosaurs (8 - 12 m). A peculiar group consisted of pterosaur lizards, which could fly thanks to a large leathery membrane stretched between the fore and hind limbs.

The extinction of ancient reptiles is associated with the cooling of the climate at the end of the Mesozoic and their inability to maintain a constant body temperature. The resulting decline in vital processes in reptiles led to a weakening of their competition with the newly emerging and rapidly progressing mammals.

Control questions:

What is the peculiarity of the organization of reptiles?

What orders are included in the class of reptiles?

What features of the skeletal structure are inherent in reptiles?

What is autotomy in reptiles?

What reproductive features are characteristic of reptiles?