Difference between reptiles and amphibians. List of reptiles and features of reptiles

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 the winter season, animals hibernate, and during periods of extreme heat they begin hunting at night.

Reptiles have tough 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 durable shell, crocodiles have hard plates of bone origin on their head and back.

Reptiles breathe only through their 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 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 a short tongue that cannot protrude. 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 the 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

One of the most famous species of reptiles are 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 - longevity. Average age Turtles have a longer lifespan than any other reptile.

Crocodiles

Animals are one of the most dangerous species of 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 of the 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 of movement on 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 coloring, 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

Currently, there are more and more lovers of 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. Domestic iguanas prefer to eat fresh fruits and vegetables, as well as herbs. 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 largest monitor lizards are the 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 climates. They are most common in Australia, Africa and southern 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 species lizards, but all together such signs are observed only in snakes.

Zmeinoye the body consists of three elements:

• head;
• body;
• tail.

Some representatives retained rudimentary forms of limbs. A large number of snake species are venomous. They have grooved or channeled teeth that contain venom. This dangerous liquid comes from the animal's salivary glands. All internal organs snakes 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. Snakes that are diurnal have a transverse pupil, while nocturnal snakes are characterized by a vertical 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 a 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.

Reptiles and amphibians are two classes of vertebrates. Not everyone can figure out which of them this or that representative of the fauna belongs to. In order to correctly navigate the existing classification, you need to know how reptiles differ from amphibians.

general information

Reptiles and amphibians have second names. Reptiles are also called reptiles, and amphibians are called amphibians. The largest animals, dinosaurs, were reptiles. Reptiles once dominated everywhere on Earth. Then most of them died out. The most famous representatives modern reptiles– crocodiles, turtles, snakes and lizards.

Reptiles

Now let's say who is amphibian. This is a frog, a newt, a salamander. Amphibians are the most primitive vertebrates in their structure. These animals have this name because the important habitat for most of them is land, and the necessary environment for reproduction and development is water. Among amphibians, there are those that spend their lives mainly in water.

Comparison

Skin covering

For reptiles, the connection with water is not so important. They often settle in dry and hot areas. Scaly skin protects the animal's body from drying out. In turtles, the shell, which serves as shelter from faster pursuers, also consists of fused scales. Reptiles molt periodically. The skin is shed all at once or in parts. Thanks to this, the scales do not hinder the growth of the animal.

The body of amphibians is not covered with scales. Many people are reluctant to touch these creatures because of their wet and slippery skin. It's all about the glands that produce mucus, which literally permeate the skin of animals.

Organ structure

The difference between reptiles and amphibians is that the former have more advanced physiology. Their nervous system complicated. Hearing, vision and other senses are quite developed. Reptiles are born with already formed lungs, while the larvae of amphibians have gills.

The structure of the spine in amphibians is simpler - it consists of four sections. The spine of reptiles is represented by five sections. In addition, tailless amphibians lack ribs.

Reproduction

Internal fertilization is a predominant feature of all reptiles. Some animals in this class, such as crocodiles, lay eggs. After some time, fully developed individuals hatch from them, differing from their parents only in size. Other species of reptiles are characterized by viviparity.

The method of reproduction of amphibians is by throwing eggs into water. The eggs glued together soon hatch into larvae, which develop into adults only after more than one month.

Lifespan

What is the difference between reptiles and amphibians when comparing the duration of existence of both? It should be noted here that many reptiles, under favorable conditions, live for a very long time - more than a dozen years. There are also centenarians among them, whose existence can last more than a hundred or even two hundred years. Such record holders are turtles.

Amphibians are not lucky enough to have such long lives. Even ten years is considered prohibitive for most of them. In captivity, the lifespan of representatives of certain species can increase. This applies, for example, to salamanders.

Amphibians and reptiles

Amphibians (amphibians), like reptiles (reptiles), are ancient terrestrial vertebrates. They are distributed everywhere, but prefer areas with warm and hot climates. Amphibians live near bodies of water and in damp places; their development occurs in water. Reptiles are not connected in their development with the aquatic environment.

Main characteristics

Fertilization is internal. Development is often direct (egg laying), and viviparity also occurs.

The meaning of amphibians and reptiles

Amphibians destroy a large number of insects - pests of agricultural crops. They are a food product for fish, birds, snakes and some fur-bearing animals. In a number of countries, frogs are also used for food by humans. The frog is a classic object for scientific research.

Reptiles are one of the links in food chains in the biosphere. Humans eat the meat and eggs of turtles, as well as the meat of snakes. The skin of snakes and crocodiles is a valuable raw material for industry. Snake venom is used to obtain medicine. The venom is collected from snakes kept in special nurseries - serpentariums. Snakes destroy a significant number of rodents - pests of agricultural crops. Amphibians and reptiles

Yaroslavl region Amphibians.

The species composition of amphibians living in the Yaroslavl region is relatively poor and is represented by 10 species. Tailed amphibians are represented by common and crested newts. Tailless frogs include two species of brown and two species of green frogs (grass, sharp-faced, lake and pond frogs), red-bellied toad, spadefoot, gray and green toads. The red-bellied firebird, spadefoot toad and green toad are listed in the Red Book of the Yaroslavl region.

Newts are tailed amphibians, somewhat reminiscent of lizards in appearance. Common and crested newts are found in our reservoirs. The most common is the common newt, reaching 8-9 centimeters in length. For breeding, newts choose well-warmed reservoirs located in clearings, forest edges and clearings. Common newts are still not uncommon in the reservoirs of city gardens and parks.

Both types of newts are extremely useful animals. Living in a pond, adult newts and their larvae destroy a huge number of mosquito larvae. Many harmful insects are eaten by newts and those living on land. And, finally, they themselves are included in the menu of many animals and birds - snakes, vipers, herons, storks, small predatory mammals. Draining of small bodies of water and the destruction of both adult newts and their eggs leads to a reduction in the number of newts.

More often than newts, frogs are found in water bodies and on land. Brown frogs differ from other frogs similar to them by a dark temporal spot. These include grass and sharp-faced. And, despite their almost identical sizes (about 8 cm) and similar colors (their backs are brown, of different shades), these frogs are easily distinguishable. The grass frog has a marbled spotted pattern on the underside of its abdomen (in males it is off-white, and in females it is reddish-brown). If you come across a frog with a uniform belly and a slightly smaller size, then it is a sharp-faced frog. The lake frog is the largest frog living in our country. The length of its body can sometimes reach 17 cm. The lake frog constantly lives in water. Pond frogs differ from lake frogs in their smaller size and emerald or bright olive color.

The common spadefoot lives on plains in the forest zone, preferring areas with loose soil. In the Yaroslavl region, rare sightings were noted in the Lyubimsky district. Listed in the Red Book of Nuclear Weapons.

The body length of the spadefoot spadefoot is up to 71 mm. The main color tone is gray or brown, on the back there is a more or less symmetrical pattern of dark spots, sometimes forming stripes; the edges of the spots are clearly defined. A light stripe runs along the back. The underparts are light with dark gray spots. A characteristic feature of this frog is the ability to quickly burrow into the soil, using its hind limbs and large calcaneal tubercle. Garlic is a dry-loving species. It is found in water bodies only during the breeding season.

Red-bellied toad inhabits low-lying areas in floodplains of rivers and lakes, ponds and swamps. In the Yaroslavl region, rare sightings were noted in the Breitovsky and Poshekhonsky districts. Listed in the Red Book.

The body length of this frog is no more than 64 mm. The back is brown-gray with dark, rarely green spots. The toad's belly is bright with large dark and orange or red spots. In case of danger, the toad takes a characteristic pose - it turns upside down, showing a bright warning color. Outside the breeding season, toaded toads prefer small sun-warmed reservoirs or shallow waters overgrown with aquatic vegetation, where they spend a lot of time. In the forest, the toad can be found on the edges, clearings and clearings.

Of the toads in the Yaroslavl region, there are gray or common and green toads. Unlike their closest relatives, frogs, toads are not demanding of water. Their skin is partially keratinized, so they can live in the forest quite far from water bodies. They bring great benefits by destroying slugs, mosquito larvae and harmful insects.

The gray toad prefers forest landscapes, but gets along well with humans and is common in parks, gardens, fields, vegetable gardens and personal plots. These animals prefer damp places with tall grass. Adult toads are active mainly at dusk and the first half of the night. In hot weather, they hide in shelters under stones, snags, and haystacks. Young toads are active around the clock, and can be found in damp places with thick grass even in hot weather.

Green toads differ from gray toads in being more varied in color: large dark green spots with a black border and red dots are scattered on the back over an olive background. Sometimes there is a light stripe along the back. The belly is whitish, with or without spots. In addition, green toads are more dry and heat-loving than gray toads. These animals are able to tolerate large losses of water and are adapted to life in very dry conditions. In the Yaroslavl region, rare sightings were noted in the Pereslavl and Rostov regions.

The number of toads is affected by human disturbance and direct extermination, as well as disturbance of natural habitats as a result of human economic activities.

Reptiles. The natural conditions of the Yaroslavl region are not very favorable for the existence of reptiles, so they are represented by six species - three species of lizards and three species of snakes.

Common grass snake and common viper can be called ordinary and widespread snakes of the Yaroslavl region. It is distinguished by yellow (or almost white or orange) spots on the sides of the head. The general color tone of the viper - a poisonous snake - varies from light gray to black. An almost black zigzag stripe stretches along the back; There is a sharp interception between the head and the body, and on the head a pattern in the form of the Latin letter “X” is clearly visible. Common vipers most often found in swampy forests on the outskirts of swamps, in forest clearings and edges with good grass stand, in clearings, along the banks of rivers and lakes. On hot sunny days, vipers crawl out to bask in the sun. At this time, they can often be seen on an old stump or even on a well-trodden forest path. Often found in garden plots and recreational areas.

According to research conducted in 2010, more than 500 thousand common vipers constantly live in the Yaroslavl region. The population of vipers is quite stable, tends to increase in number and does not yet require additional protection measures.

By destroying mouse-like rodents, snakes and vipers bring considerable benefit.

In the Yaroslavl region, sporadic encounters of the copperhead snake, which has an international protection rank, were noted in the Pereslavl region. The copperhead belongs to the snake family. When meeting a person, this snake usually curls up into a tight ball, inside which it hides its head, and reacts to all touches by compressing its body even more. The copperhead is listed in the Red Book of the Yaroslavl region.

Of the lizards, the two most common types of true lizards are the fast lizard and the viviparous lizard. They are small in size - the first is no more than 25 centimeters (including the tail), the second is slightly shorter - 20 centimeters. The sand lizard can even be found in a city park. It adapts well to human-modified landscapes, preferring dry and sunny areas, hillsides and even railway embankments. The viviparous lizard lives in wetter places, in forested areas of swamps, peat bogs, overgrown clearings, and along river banks.

Both types of lizards are useful; they destroy slugs, mole crickets, caterpillars, harmful insects and their larvae.

In the Yaroslavl region, there is also a legless lizard - the brittle spindle, or copperhead. Unfortunately, this animal is often confused with the copperhead snake and other snakes (including poisonous ones), frightened and even destroyed. The serpentine body of the spindle reaches a length of 60 cm (including the tail). Young animals are usually very light colored. Adults are brown or bronze in color on top with darker sides. The bottom is bluish-black. Males have blue or blue spots on their backs. The lizard's body is covered with small, very smooth and shiny scales.

In our area, the spindle is found much less frequently than other lizard species. It lives mainly in mixed and deciduous forests, also found at the forest border on the outskirts of fields and meadows, in forest clearings and clearings, and in gardens. Useful.

Reptiles – what kind of animals are they? They belong to the class of vertebrates, occupying a place between amphibians and mammals. We also call them reptiles. Reptiles are a list of names below:

— dinosaurs (fossil form);
- lizards;
- turtles;
- snakes;
- crocodiles.

Lifestyle

Reptiles adapt to the ambient temperature, being cold-blooded. To avoid freezing during the cold season, some may go into seasonal hibernation. When the temperature, on the contrary, is too high, they are more active at night. Reptiles have tough skin covered with scales. The main task of the scales is to protect them from drying out. Turtles have a strong shell, while crocodiles have hard plates on their backs and heads. The bone skeleton of these animals is well developed. The ribs of snakes are designed so that they crawl with ease. Most reptiles have a short tongue. Only lizards and snakes have a long, forked one that can extend from the mouth. The reproductive organs are similar to those of birds. Some eggs remain inside until they hatch.

Reptile animals examples: lizards

Lizards are the largest group of reptiles. This is sometimes the name given to all reptiles with legs, except crocodiles and turtles. However, it is worth highlighting real lizards and related species.

True lizards are small or slightly larger than average. The length reaches a maximum of 80 cm, although generally 20-40 cm. Their body, limbs, and color are adapted to their habitat. Desert representatives have long toes on their paws with lateral teeth that prevent them from sinking into the sand. Interestingly, in case of danger, the lizard itself breaks its tail to distract the attacker. While the owner runs away, the tail continues to wriggle, distracting the predator. Males are larger than females and more brightly colored. The color is predominantly green, gray, brown colors. Desert ones are colored yellow. For the most part, lizards do not make sounds. Only Stechlina and Simona, who live on the Canary Islands, squeak in case of danger.

Area

They live mainly in Europe, Africa, and Asia. IN North America they were brought in. You can see a lizard in a forest, meadow, desert, steppe or even in a garden. These reptiles instantly climb low bushes, crawl along tree trunks and grass stems. Nimble and maneuverable, they easily move along a vertical surface.

Lizards are active early in the morning or at sunset. Less active during the day. Very cautious, they immediately freeze as soon as they sense danger. When a suspicious object approaches, they run away. Interestingly, desert species instinctively raise their paws one at a time to avoid getting burned by the hot sand.

Nutrition

Feeds this type reptiles and invertebrates. Larger representatives can catch a small rodent, a snake, or eat a bird's nest. They love to feast on spiders, butterflies, and grasshoppers. Snails and worms are rare, but are found in their diet. Some species do not disdain plant fruits.

Protection from enemies

Snakes are hunting these beauties, big birds. To protect themselves, lizards use several methods: fast running, freezing, camouflage. Interestingly, it is almost impossible to throw a lizard that is hiding from a bush. If caught, it instantly throws off its tail or bites hard. It can grab itself by the leg and twist itself into a ring - an excellent defense against a snake, because in this form the latter will not be able to swallow its prey.

Reptiles examples: turtles

Let's continue our acquaintance with reptiles, the list of names continues with turtles - the most known species reptiles. There are land and sea. Distributed throughout the world. You can keep them as a pet.

Description of turtles

The shell has a bone structure. The respiratory organ is the lungs. Aquatic animals absorb air using the mucous membrane of the pharynx. The main difference from other reptiles is longevity. The largest representatives of this species are marine. The length of the shell of the largest is 2 m, and it weighs more than 900 kg. The smallest turtle is only 10 cm long.

Reproduction

To lay eggs, the female makes a pitcher-shaped hole. Then laying future mom falls asleep, tamps down thoroughly. Depending on the variety, the number of eggs ranges from one to two hundred.

Character

By nature, these reptiles are solitary. They communicate with their own kind only in mating season. Land animals mainly use plants as food, but freshwater animals are predators. It happens that children can lead a predatory lifestyle, and as adults switch to plant foods.

Reptiles Examples: Snakes

The main difference from other reptiles is body shape

In the body of these reptiles we will find three elements: the head, the body itself, and the tail. They have no limbs, eyelids, or external auditory canal.

Differences from reptiles

Most snakes are poisonous. The poison is contained in the teeth. The internal organs of these reptiles are very different. For example, there is no bladder. The eyes have a cornea. Nocturnal representatives have a transverse pupil, while nocturnal ones have a vertical pupil. They can only hear loud sounds.

Separately, it is worth highlighting the snakes

These snakes are not poisonous. The scales are brightly colored. They live near bodies of water. They feed on fish and can catch small mammals. They swallow their prey whole. If it senses danger, it freezes, and when an enemy approaches, it secretes a stinking liquid from its mouth. Reptiles breed on plant soil.

Reptile animals examples: crocodiles

Most dangerous look reptiles. The size of the ancient representatives exceeded 15 meters in length. Remains have been found on all continents. Modern crocodiles are much smaller, but they are still the largest reptiles.

Way of life

Most of the time they are in the water. On the surface there are only the organs of vision, hearing, and nose. The tail and paws are webbed, which allows them to swim well. However, on greater depth crocodiles don't swim. These reptiles make their nests on land. They come out of the water only to warm themselves. They have a powerful tail and move quickly in water and on land. They attack unexpectedly. Therefore, they are extremely dangerous for humans.

Reptiles, list: let's summarize

In total, more than six thousand reptiles are known to man, which are distributed throughout to the globe. They mainly live on land. A warm climate with moderate humidity suits them best. However, among reptiles there are desert inhabitants. Most representatives of snakes and crocodiles are very dangerous to human life. However, these reptiles also have benefits. For example, scientists have learned to use snake venom for medicinal purposes. It increases blood clotting, drugs based on it reduce pain in rheumatism and neuralgia. More than two thousand snakes are not poisonous at all, but they feed on harmful rodents, reducing their numbers in their habitat. Expensive haberdashery products are made from crocodile skin. Reptile meat is also used for food and is considered a delicacy. In this sense, eggs and turtle meat are valued.

Reptiles, like any other animals, can pose some danger to humans, only if they are handled incorrectly. IN modern world You can admire an alligator or a rattlesnake without fear for your own life. Meeting in real life There is practically no threat to us with them.

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 that 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 eggs tailless amphibian, for example, 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; The nervous system is better developed than that of amphibians: the cerebral hemispheres are much larger (see Fig. 85). The behavior of reptiles is much more complex than that of amphibians. In addition to innate unconditioned 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 the 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 bone 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, and 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 agricultural pests (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