How are reptiles different from amphibians? Amphibians and reptiles - common characteristics of amphibians and reptiles

Reptiles- typical terrestrial animals and their main method of movement is crawling, reptiles on the ground. The most important structural features and biology of reptiles helped their ancestors leave the water and spread widely across the land. These features primarily include internal fertilization And egg laying, rich in nutrients and covered with a dense protective shell, which facilitates their development on land.

The body of reptiles has protective formations in the form scales, covering them with a continuous cover. The skin is always dry, evaporation through it is impossible, so they can live in dry places. Reptiles breathe exclusively with the help of their lungs, which, compared to the lungs of amphibians, have a more complex structure. Intensive lung breathing became possible thanks to the appearance of a new skeletal section in reptiles - chest. The chest is formed by a number of ribs connected on the dorsal side to the spine, and on the abdominal side to the sternum. The ribs, thanks to special muscles, are mobile and contribute to the expansion of the chest and lungs during inhalation and their collapse at the moment of exhalation.

Changes in the structure of the respiratory system are closely related to changes in blood circulation. Most reptiles have a three-chambered heart and two circuits of blood circulation (as do amphibians). However, the structure of the reptile heart is more complex. In its ventricle there is a septum, which at the moment of contraction of the heart almost completely divides it into the right (venous) and left (arterial) halves.

This structure of the heart and the location of the main vessels, different from that of amphibians, more strongly delineates the venous and arterial flows, therefore, the body of reptiles is supplied with blood that is more saturated with oxygen. The main vessels of the systemic and pulmonary circulation are typical of all terrestrial vertebrates. The main difference between the pulmonary circulation of amphibians and reptiles is that in reptiles the cutaneous arteries and veins have disappeared and the pulmonary circulation includes only pulmonary vessels.

About 8,000 currently existing species of reptiles are known, living on all continents except Antarctica. Modern reptiles are divided into orders: protolizards, scaly, crocodiles And turtles.

Reproduction of reptiles

Fertilization in terrestrial reptiles internal: the male injects sperm into the female’s cloaca; they penetrate the egg cells, where fertilization occurs. The female's body develops eggs, which she lays on land (buries in a hole). The outside of the egg is covered with a dense shell. The egg contains a reserve nutrients, due to which the development of the embryo occurs. The eggs do not produce larvae, as in fish and amphibians, but individuals capable of independent life.

First Lizard Squad

TO proto-lizards refers to "living fossil" - tuateria- the only species that has survived to this day only on small islands near New Zealand. This is a sedentary animal, leading a predominantly nocturnal lifestyle and similar in appearance to a lizard. Hatteria in its structure has features that are similar to reptiles and amphibians: the vertebral bodies are biconcave, with a chord preserved between them.

Otrad scaly

Typical representative scaly - quick lizard. Her appearance indicates that this is a terrestrial animal: the five-fingered limbs do not have swimming membranes, the fingers are armed with claws; the legs are short, and therefore the body, when moving, seems to crawl along the ground, every now and then coming into contact with it - reptiles (hence the name).

Lizards

Although the lizard's legs are short, it can run quickly, quickly escaping from its pursuers into its burrow or climbing a tree. This was the reason for its name - quick. The lizard's head is connected to the cylindrical body using the neck. The neck is poorly developed, but will still give the lizard's head some mobility. Unlike a frog, a lizard can turn its head without turning its whole body. Like all land animals, it has through nostrils, and its eyes have eyelids.

Behind each eye, in a small depression, is the eardrum, connected to the middle and inner ear. From time to time, the lizard sticks out of its mouth a long, thin tongue forked at the end - an organ of touch and taste.

The lizard's body, covered with scales, rests on two pairs of legs. The humerus and femur bones are parallel to the surface of the earth, causing the body to sag and drag along the ground. The ribs are attached to the thoracic vertebrae, forming the rib cage, which protects the heart and lungs from damage.

The digestive, excretory and nervous systems of the lizard are basically similar to the corresponding systems of amphibians.

Respiratory organs - lungs. Their walls have a cellular structure, which significantly increases their surface area. The lizard does not have skin respiration.

The lizard's brain is better developed than that of amphibians. Although it has the same five sections, the forebrain hemispheres are larger in size, and the cerebellum and medulla oblongata are much more massive.

The sand lizard is distributed very widely from the Black Sea to the Arkhangelsk region, from the Baltic Sea to Transbaikalia. In the north, it gives way to a viviparous lizard similar to it, but more adapted to the cold climate. In the southern regions there are many different types lizards Lizards live in burrows, which in summer weather they leave in the morning and evening, but no further than 10-20 m from the burrow.

They feed on insects, slugs, and in the south - locusts, caterpillars of butterflies and beetles. Within a day, one lizard can destroy up to 70 insects and plant pests. Therefore, lizards deserve protection as very useful animals.

The lizard's body temperature is not constant (the animal is active only in the warm season); it drops sharply even if a cloud approaches the sun. With a longer drop in temperature, the lizard loses mobility and stops eating. During the winter it hibernates; can tolerate freezing and cooling of the body down to -5°, -7°C, while all the life processes of the animal slow down significantly. Gradual warming returns the lizard to active life.

In addition to the sand lizard and viviparous lizard, there are many other species of lizards. Common in Ukraine and the Caucasus large green lizard: in desert areas - agama lizards with a long flexible and unbreakable tail.

Predatory lizard gray monitor lizard, living in the deserts of Central Asia. Its length is up to 60 cm. The monitor lizard eats arthropods, rodents, eggs of turtles and birds. The largest specimens of monitor lizards discovered by herpetologists (the science that studies reptiles) on the island of Komolo reach 36 cm. In the northern regions, the legless lizard is common - spindle.

Chameleons

Chameleons in appearance they resemble medium-sized lizards, with a helmet-shaped outgrowth on the head and a laterally compressed body. This is a highly specialized animal, adapted to an arboreal lifestyle. His fingers are fused together like pincers, with which he tightly grasps the branches of trees. The long and prehensile tail is also used for climbing. The chameleon has a very unique eye structure. The movements of the left and right eyes are not coordinated and independent of each other, which provides some advantages when catching insects. Interesting feature Chameleon's ability to change skin color is a protective device. Chameleons are common in India, Madagascar, Africa, Asia Minor and southern Spain.

Snakes

In addition to lizards, the order Squamate includes snakes. Unlike chameleons, snakes are adapted to crawling on their stomachs and swimming. Due to wave-like movements, the legs gradually completely lost their role as organs of locomotion; only some snakes retained their rudiments (a boa constrictor). Snakes move by bending their legless body. Adaptation to crawling was manifested in the structure internal organs snakes, some of them completely disappeared. Snakes have no bladder and only one lung.

Snakes see poorly. Their eyelids are fused, transparent and cover their eyes like a watch glass.

Among snakes there are non-venomous and poisonous species. The largest non-venomous snake is boa- lives in the tropics. There are boas up to 10 m long. They attack birds and mammals, strangling their prey by squeezing it with their body, and then swallowing it whole. Large boas living in tropical forests, are also dangerous for humans.

Widespread of non-venomous snakes snakes. The common snake is easily distinguished from poisonous snakes by two orange crescent spots on the head and round pupils of the eyes. It lives near rivers, lakes, ponds, feeding on frogs, and sometimes small fish, swallowing them alive.

Poisonous snakes include viper, cobra, or spectacled snake, rattlesnake and etc.

Viper easily recognized by the long zigzag dark stripe running along the back. In the upper jaw of the viper there are two poisonous teeth with tubules inside. Through these tubules, the poisonous liquid secreted by the victim enters the wound. salivary glands snakes, and a prey such as a mouse or small bird, dies.

By destroying huge numbers of mice and locusts, vipers benefit humans. However, their bites can cause long-term illness and even death in animals and even humans. The venom of such snakes as asian cobra, American rattlesnake.

Wounds formed when a person is bitten by a snake look like two red dots. Painful swelling quickly occurs around them, gradually spreading throughout the body. A person develops drowsiness, cold sweats, nausea, delirium, and in severe cases, death occurs.

If a person is bitten by a poisonous snake, it is necessary to immediately take first aid measures., remove excess poison near the wound with blotting paper, cotton wool or a clean cloth, if possible, disinfect the bite site with a manganese solution, strictly protect the wound from contamination, give the victim strong tea or coffee, and ensure rest. Then take him to the hospital as quickly as possible for immediate administration of anti-snake serum. Where they are found Poisonous snakes, you can't walk barefoot. Care must be taken when picking berries, protecting your hands from snake bites.

Otrad crocodiles

Crocodiles- these are the largest and most highly organized predatory reptiles, adapted to an aquatic lifestyle, living in tropical countries. Nile crocodile Spends most of its life in water, where it swims beautifully, using a strong, laterally compressed tail, as well as hind limbs that have swimming membranes. The crocodile's eyes and nostrils are elevated, so it only needs to raise its head out of the water a little and it can already see what is happening above the water, and also breathe atmospheric air.

On land, crocodiles are slow to maneuver and, when in danger, rush into the water. They quickly drag their prey into the water. These are various animals that the crocodile lies in wait at watering places. It can also attack humans. Crocodiles hunt mainly at night. During the day they often lie motionless in groups on the shallows.

Turtle squad

Turtles differ from other reptiles in their well-developed, durable shell. It is formed from bone plates, covered on the outside with horny substance, and consists of two shields: the upper convex and the lower flat. These shields are connected to each other from the sides, and there are large gaps in front and behind the joints. The head and forelimbs are exposed from the front, and the hind limbs from the back. Almost all aquatic turtles- predators, land animals - herbivores.

Turtles typically lay hard-shelled eggs on land. Turtles grow slowly, but are among the long-livers (up to 150 years). There are giant turtles (soup turtle up to 1 m long, weight - 450 kg, swamp turtle - up to 2 m and up to 400 kg). They are objects of fishing.

Meat, fat, eggs are used for food, and a variety of horn products are made from the shell. We have one species of turtles - marsh turtle, lives up to 30 years. During the winter it hibernates.

Reptiles, unlike amphibians, became independent in their development from aquatic environment. Amphibians breed in water, their larvae live in water. Reptiles breed on land, and their young also live on land.

The main evolutionary innovations (aromorphoses), which allowed reptiles to better adapt to life on land and distinguished them from amphibians, were the following: the appearance of the chest, a more complex structure of the lungs and respiratory tract, the appearance of a septum in the ventricle of the heart, the appearance of the rudiments of the cerebral cortex, the formation of embryonic membranes, keratinization of the skin. The differences between reptiles and amphibians are listed in more detail below.

There are more sections in the spine of reptiles. If amphibians have cervical, trunk, sacral and caudal sections, then reptiles have cervical, thoracic, lumbar, sacral and caudal sections. That is, the trunk region is differentiated into the thoracic and lumbar regions. However, some biologists combine the thoracic and lumbar regions into one - thoracolumbar.

In amphibians, the cervical spine consists of only one vertebra. In contrast to them, in reptiles cervical spine There are significantly more vertebrae (8 in lizards). In addition, in reptiles the skull is connected to the first cervical vertebra with one condyle, and not two. And the first cervical vertebra can rotate relative to the second cervical. All this increases the mobility of the head of reptiles by an order of magnitude. If amphibians can only tilt and raise their heads, then reptiles can also freely turn their heads from side to side. This allows you to better inspect the area around and catch prey.

The ribs of reptiles are well developed. They grow from all vertebrae of the lumbar-thoracic region. However, only the first (in lizards the first five pairs) grow on the ventral side to the sternum, thus forming the chest. Unlike reptiles, amphibians do not have a thorax. The ribs are either short or absent altogether. The rib cage protects the internal organs.

In addition, thanks to the intercostal muscles, a more advanced breathing mechanism is possible, when air is sucked into the lungs due to the expansion of the chest, and expelled due to its reduction. In amphibians, air is pushed through the oropharyngeal cavity.

The sacral spine of reptiles consists of two vertebrae, but of amphibians only one. The iliac bones of the pelvic girdle are attached to both vertebrae.

The shoulder girdle of reptiles is connected to axial skeleton(spine) through the sternum. In amphibians, the shoulder girdle lies freely in the thickness of the muscles.

In reptiles, the skeleton ossifies more strongly, but the bones become lighter.

The lungs are also improving. Numerous folds and a well-defined cellular surface appear in them. All this increases the inner surface of the lungs, which means gas exchange is more efficient. As a result, reptiles, unlike amphibians, no longer need to compensate for the lack of oxygen by breathing through the skin.

Reptiles cannot breathe through their skin, as it is covered with horny scales. They do not allow air to pass through well, but they protect the reptile’s body well from water loss, which is important when living in a dry terrestrial environment.

The hearts of reptiles and amphibians also differ, although in both groups of organisms they have three chambers (two atria and one ventricle). In reptiles, the pulmonary artery and two aortic arches emerge from the ventricle of the heart independently, and inside the ventricle there is an incomplete septum. All this allows for better separation of arterial and venous blood. Although in reptiles it is still partially mixed.

In reptiles, the pelvic kidneys function (and not the trunk kidneys like in amphibians). The structure of the kidneys allows less water to be excreted from the body along with urine. The main excretion product of reptiles is uric acid, which is poorly soluble in water, and their urine has a mushy appearance.

A number of changes also occur in the nervous system of reptiles that distinguish them from amphibians. This applies to a greater extent to the brain. Reptiles have a larger cerebellum than amphibians. This is due to the more complex movements of the former. Reptiles have better developed vision (they see well not only moving, but also stationary objects); some species (snakes) have organs that detect thermal radiation.

Due to the fact that reptiles reproduce on land, external fertilization is excluded. Therefore, fertilization is internal, when the egg is fertilized by a sperm inside the female's reproductive tract. After this, the egg is formed. In embryos, membranes develop in it (amnion and allantois), which are not found in amphibians.

The development of reptiles is direct. From the egg comes a small reptile that looks like an adult. In amphibians, development proceeds with metamorphosis, when the larva (for example, a tadpole in frogs) does not resemble an adult individual and leads a different lifestyle.
Thus, the difference between reptiles and amphibians lies in the better adaptation of the former to life in terrestrial conditions.

The green jumping creature - the frog - stands among those animals with which we become acquainted already in childhood. For many, it forever remains only a slippery and unpleasant creature that lives in any pond or river of any size, and splashes noisily into the water from under the feet of those passing along the shore. But, although. It would seem that. There is nothing more common than our simple green frog, even the very definition of it as “a green jumping creature that lives in the water” is only slightly true (Fig. 1).

Amphibians

Let's start with the fact that only fifteen percent of the world's fauna frogs have connected their lives with water. The rest live in different places: a number of tropical and subtropical frogs spend almost their entire lives on trees, reeds and other vegetation, and our grass and sharp-faced frogs live in forests and meadows, sometimes in very dry areas.

And not all frogs can jump. Some people just don't need it: you might fall out of a tree. And other species lead an underground lifestyle; underground you can’t jump much, so they only know how to crawl.

And even the proverbial green color we can find skins among the frog tribe quite rarely. It turns out that most frogs are not green at all, but brown, gray, blue, and among them there are even yellow and red ones.

You don’t need to think that only in the distant tropics you can find various exotic frogs. No, an ordinary frog living in a neighboring pond turns out to be no less interesting upon closer acquaintance.

In the territory Samara region only four species live out of more than five thousand species of frogs, counted by zoologists of the world. The pond frog should rightfully be called the rarest among us. This is a European animal, and the eastern border of its distribution runs through the territory of our region. As elsewhere on the outskirts of its range, it is found here quite rarely. It is believed that the bulk of our pond frogs live west of the Volga. To the southeast of our region you will no longer find it, but to the northeast on the left bank, isolated finds of this animal are known in the Dimitrovgrad area up to the Ik River basin (Fig. 2).

Another of our frogs, the grass frog, prefers more northern areas. And the border of its range runs through the territory of the region, this time to the south. In the east, it settled as far as the Urals, and in some places as far as the Ob. And in the north, the grass frog reached the latitude of Murmansk, far beyond the Arctic Circle (Fig. 3).

Most often in the Middle Volga region we will find two other species of frogs - lake and sharp-faced, and here they clearly divided their spheres of influence. If the lake fish is a widespread species in reservoirs of various types, from large puddles to Volga bays, then the sharp-faced fish sticks to drier places and can be found in meadows and forests. And on a national scale, the sharp-faced frog holds the lead among all other frogs in terms of the size of its range. It extends from the western borders of the USSR to Lake Baikal, from Murmansk to southern Ukraine (Fig. 4, 5).

Of all four relatives, perhaps the pond frog most corresponds to our idea of ​​the frog tribe. She is the only one among the representatives of the family living in our region that has a purely green color of various shades. In addition, she almost never leaves her native pond, where she was born and raised.

But the lake frog can be called green only partly, with a stretch. Her skin has a brown coloration with transitions to a dirty green color. This is our largest frog. In the Volga region, its specimens have been recorded with a body length (excluding leg length) of up to 14 centimeters, and in general lake frogs up to 17 centimeters in length are known. These are real giants among our amphibians. In some places in one square kilometer of the Volga floodplain, about six hundred lake frogs live.

The razor-faced frog and the grass frog are quite similar - both are brown to brown to yellow in color. They are sometimes distinguished by size. Body length grass frog reaches ten centimeters, but the sharp-faced one, as a rule, has no more than eight centimeters. But their main difference is the color of the belly. The vast majority of sharp-faced frogs have a white lower body without any spots, while the grass frog always has a spotted belly with a special “marble” pattern.

The role that frogs have played and still play in the work of scientists is well known. As a sign of gratitude to these truly irreplaceable laboratory animals, monuments have been erected in some cities around the world.

Frogs are just one of the families of a large order of so-called tailless amphibians (this feature distinguishes them from the group of tailed amphibians, which will be discussed below). Tailless include all other “frog-like” amphibians - tree frogs, toads, spadefoots; but the most similar to real frogs are, perhaps, toads. They are classified as a special family of round-tongues. The main difference between toads and frogs is the following: the latter’s tongue is capable of throwing itself out of the mouth and capturing flying insects, while round-tongues are not capable of this.

One species from this group is found on the territory of the region - the red-bellied toad. (Fig. 6, 7)

Its underparts are red or bright orange with bluish-black spots. Usually toads are very few in number in reservoirs, but sometimes they are found in large numbers in floodplain, well-warmed lakes with a clay bottom in the valleys of the Volga, Samara and other rivers. Here their number can reach from 40 to 80 individuals per hectare of reservoir. The toad has such numbers in lakes where the water temperature is about 200C, where mosquito larvae, aquatic worms, mollusks, and other invertebrates have multiplied en masse. Then in evening hours There is a rumble over the lake - at this time the toaded toads are loudly singing “uu... oo... oo”; their voices are easily distinguished from the croaking song of frogs.

The mucous secretions from the toad's skin are poisonous. When in danger, she bends and rolls over onto her back. As a result, its bright warning color becomes visible - those same red and blue spots that scare off a predator.

The spadefoot, contrary to its name, does not smell of garlic at all and has nothing to do with it at all (Fig. 8).

This type of amphibian is widespread in our region, but, however, no matter who you ask, no one knows what kind of animal we are talking about. Meanwhile, many, especially villagers, often encounter spadefoots - they just call it, as a rule, a ground frog. This amphibian has a nondescript gray-brown body color and very bright spots scattered along its back. And, in fact, she leads a burrowing lifestyle, hiding underground during the day. Thanks to this, the spadefoot often finds its way into cellars, basements, and underground storage facilities, where we most often see this “ ground frog" And outside such places, we can see the spadefoot only at night, when it comes out of its burrows to feed on various small living creatures - slugs, worms, caterpillars, ants and others.

Toads also lead a similar lifestyle, of which there are two species in the Samara region: gray and green (Fig. 9, 10).

Toads can be easily distinguished from frogs and other similar amphibian toads by two characteristic swellings located on the sides of the head and behind the eyes - the parotid glands. Toads jump extremely rarely and reluctantly; they don’t need this - after all, toads’ night prey is sedentary organisms such as insects, centipedes, worms, mollusks and others. Along with spadefoot, toads are a very welcome guest in any garden; Several of these amphibians can completely destroy all pests here in a short time, and then maintain it in this state indefinitely.

According to Kazan herpetologist V.I. Garanina, in the Middle Volga region the green toad should be considered a more common species. Unlike the gray toad, it has a gray-cream color, and on its back it has large dark green spots, trimmed with a narrow black border. The body length of the green fellow is no more than 14 centimeters; In contrast, the inconspicuous gray toad reaches a length of twenty centimeters or more. IN AND. Garanin also revealed that, although it lives in almost all suitable places in our region (in forests, gardens and parks, forest-steppe ravines, forested swamps), avoiding only wide river floodplains, the number of the gray toad in biocenoses is small - only about 10 percent of the number all amphibians.

Perhaps toads are a classic example of an animal that causes disgust and other negative emotions the vast majority of people, but at the same time they are extremely useful creatures for humans. The unpleasant appearance and nocturnal lifestyle have associated a number of corresponding gloomy legends with the toad: they supposedly cause warts on the skin of people, and even allegedly suck milk from cows at night... All of these are superstitions, but, however, such tales in many cases literally cost the lives of these harmless and useful creatures.

As already mentioned, all the amphibians mentioned above belong to the order of anurans; In our fauna, however, there are also tailed amphibians. These include two types of newts: crested and common (Fig. 11-13).

The first of these two creatures is a rather rare species in our region. On the territory of the Samara region, according to information from V.I. Garanina, passes the southern border of the range of the crested newt; it is noted in our lakes Samara Luka and floodplain reservoirs of the Samara River. In the steppe part of the region there are practically no places where there would be favorable conditions for its habitat, so we can consider that the floodplain of the Samara River is the southern border of the distribution of the crested newt in the region and in Russia.

The number of this species in biocenoses is only about nine to ten percent of the total number of all amphibians; On average, for every one crested newt in water bodies there are four to six common ones. This latter species is found almost throughout the region.

In summer, both newts very often leave the water and spend several days in damp, shady places, where they feed on soil and terrestrial invertebrates. When comparing representatives of these two species, it is quite easy to distinguish from each other: the body of the crested newt often reaches ten centimeters in size, while the common one is extremely rarely even six centimeters in length. In addition, the latter species always has dark longitudinal stripes on its head, one of which, the largest, necessarily passes through the eye, while the skin of this animal is smooth and slippery. On the contrary, the crested newt never has stripes on its head; its skin, unlike that of the common newt, is rough and rough. Moreover, during the mating season, male common newts are quite similar to crested newts. But they still have the above differences.

Reptiles

Most people treat reptiles in much the same way as they treat amphibians. In the minds of many, these are the same nasty, cold and slippery creatures; and as for snakes, they are generally considered one of the most terrible creatures - after all, the look of a snake is hypnotizing, it penetrates everywhere unnoticed, and, in addition, it is poisonous...

Fear, as you know, has big eyes - almost all of this is fiction. Regarding the latter property, fears, as a rule, are greatly exaggerated - only one tenth of all known to science snakes are poisonous. In the Samara region, 11 species of reptiles are now known, and six of them are snakes, but only two are poisonous: the steppe viper and the common viper. The first is somewhat smaller: steppe vipers generally do not exceed 55 centimeters in length, while common vipers reach 75 or even more (Fig. 14, 15).

Both of these species are very variable in body color. The steppe viper most often has individuals that are brownish-gray in color, usually lighter along the back, while the common viper has grayish or brownish-red tones. Both snakes have a dark zigzag stripe along their spine. Among other things, the common viper has an X-shaped pattern on its head, and a dark line runs from the eye to the corner of the mouth. However, in both species of these snakes there are individuals with a darker color than normal, and occasionally even completely black. Scientists come across an ordinary viper in such “clothing” much more often than a steppe viper. Thus, herpetologist V.G. Barinov identified very interesting fact: it turns out that only the exclusively black form of the common viper lives on the territory of Samarskaya Luka. At the same time, it was found that all her cubs have a lighter color, and a zigzag line on the back is clearly visible from them. Gradually, small snakes darken, and when they finally mature at two or three years of age, they are already painted solid black.

Steppe viper - southern species; its main habitat is Kazakhstan, the Don and Volga steppes, and southern Ukraine. It has not been found anywhere north of the mouth of the Kama. In our region, as a rule, it lives only in the zone of true steppes. Against, common viper– northern view; certain parts of its range even extend beyond the Arctic Circle, into the Murmansk and Arkhangelsk region. The southern border of the distribution of this snake coincides with the westernmost points of advancement to the south of the forest-steppe natural zone. The mentioned line runs throughout Eurasia, coinciding with cities such as Chisinau, Kharkov, Samara, Chelyabinsk, Novosibirsk. At the same time, our region, in particular Samara Luka, turns out to be one of the most northern places her habitat in Russia.

But how deadly are the poisonous teeth of the mentioned vipers? It turns out, oddly enough, these “terrible” snakes of our region are of little danger to humans. Thus, science does not know of a single case of death from a human being bitten by a steppe viper in hundreds of years of medical history. During this same time, however, several cases of death of people from the bite of a common viper were identified, but experts consider it unclear whether in each specific case the death of a person was a consequence of poisoning by snake venom or incorrect treatment methods.

The harm from vipers is thus minimal. At the same time, the benefits from them are enormous - these snakes destroy hordes of mouse-like rodents and even harmful insects, primarily locusts. And to obtain healing snake venom, vipers are kept in special nurseries; medicinal preparations, created on its basis, have already saved the lives of thousands of people. So the question - is it worth grabbing a stick when meeting a snake - should be resolved unambiguously, in favor of the reptile; Moreover, these animals are never the first to attack a person, but, on the contrary, try to hide unnoticed.

If vipers are known as poisonous snakes, then snakes, on the contrary, are harmless and not dangerous to humans. In our region there are two types of them - ordinary and water. It is quite easy to distinguish these snakes from each other: the common snake has clearly visible yellow or orange spots on its temples; the water snake has nothing like that. If the first reaches 120 centimeters in body length, then the second – even 130 centimeters (Fig. 16, 17).

The common one is a very common inhabitant of various places in the Samara region. Most often, such places are in the vicinity of reservoirs - rivers, floodplains and other lakes, springs, ravines. This snake uses piles of brushwood, voids under stones and rhizomes, hollows, and burrows of various animals as shelter.

And the water ear got its name because in life it is much more connected with water than all other types of snakes. The water snake always lives near flowing or stagnant bodies of water, crawling onto rocky slopes only to rest and feed. This species is very rare in the region. For us, the water snake is most interesting because in the Samara region there is the northernmost point of its habitat in the USSR - this, of course, is Samara Luka. It is similar to vipers in its variegated body coloring, but this pattern looks like dark spots on a light background, rather than a zigzag line.

In our region there are several places where the numbers of both common and water snakes are very high. First of all, we should name the area of ​​​​the Snake Backwater in the south of Samarskaya Luka (apparently, this Volga bay received such a name for a reason). According to V.G. Barinova, in the vicinity of the backwater there are up to 22 common and 24 water snakes per kilometer of the route; this is almost 10 times more than the regional average. However, even in this place the number of snakes is last years is steadily declining. According to the calculations of herpetologist V.M. Shaposhnikov, in just six years the number of water snakes in the Zmeiny Zaton area has fallen by five to seven times, mainly due to their direct destruction by humans and due to the increased disturbance factor.

Just like for the water snake, Samarskaya Luka is now the northernmost location in the country for another snake - the patterned snake. This is a very interesting reptile; back in 1935, zoologist I. Bashkirov described it for Zhiguli as a relict species of the Neogene period. Samarskaya Luka is an isolated habitat in the country; In other places in the region, snake finds are still unknown. It exists only in regions of the country more south than our region (Fig. 18).

This snake, sometimes reaching a meter in length, is usually gray in color with a brownish tint, sometimes with a brown or reddish tint. Along the body of the patterned snake, as a rule, there are four wide, blurred brown lines, of which the middle two go to the tail. The snake's head is crowned with a characteristic pattern consisting of an arched transverse stripe in front, a longitudinal stripe in the center and two spots on the sides. The spotted snake is a non-venomous snake; its food is small rodents, occasionally birds, their eggs, and small reptiles. It most often sticks to open, rocky mountain slopes overgrown with grass and sparse shrubs, where it prefers to be in well-lit areas.

V.G. Barinov believes that on Samarskaya Luka the number of snakes is small, but in a number of places its population density reaches significant values. If on Bolshaya Bakhilovaya Mountain for many years it has remained at the level of two or three snakes per kilometer of the route, then at the Snake Backwater after the 70s it dropped from 11 to 4 individuals per kilometer and has stabilized at this level for now. In addition, new populations of the patterned snake were discovered not so long ago - in the area of ​​Mount Lbishche (4-5 snakes per kilometer) and near the village of Mordovo (on average about 7 individuals per kilometer).

A number of legends and superstitions are associated with the copperhead; The most common of them, perhaps, is the belief that it is supposedly poisonous. In fact, a copperhead bite can cause redness and inflammation of the skin around the affected area only due to the fact that its teeth almost always contain cadaveric venom - a consequence predatory image life. After all, the copperhead does not even kill its prey - mice, frogs, lizards and other small animals - with a bite, as, for example, a viper does, but strangles it with the rings of its body, like a boa constrictor and a snake.

When meeting this snake, you need to know that in a moment of danger, the copperhead curls up into a tight ball, and reacts to touches only by even more compression of the body and can only make short throws from the ball with a hiss; taken in hand, it begins to bite furiously.

The copperhead is a purely European species; in the east its range reaches only the Urals, in the south – to the Caucasus and in the north – to Leningrad. This snake lives in deciduous, coniferous and mixed forests, where it sticks to the edges well warmed by the sun. Quite numerous in the south of its range, in the central zone of the USSR the copperhead becomes very rare. So, V.G. In eight years of observing the reptiles of the Samara Luka, Barinov met only 12 copperheads, mainly on the outskirts of forests, as well as on the gradual slopes of Zhiguli. There are also copperheads here and there in other places in the region, but there they are found in literally single specimens.

This snake got its name for its characteristic color - most male copperheads are reddish, and females are brownish, sometimes both have a real copper-red color. However, this species also has a solid black color. It is interesting that according to Academician A.G. Bannikov (this follows from the 1977 edition of the “Identifier of Amphibians and Reptiles of the Fauna of the USSR”) completely black individuals of this species are never found in our country; meanwhile V.G. Barinov twice on Samarskaya Luka (near the village of Gavrilova Polyana and near the village of Vinnovka) met copperheads, so to speak, in “complete mourning.” Another mystery of Samara Luka?

Uninformed people often confuse copperhead and spindle; meanwhile, the latter differs from the copperhead in its small size - no more than 25 centimeters in length. In addition, the spindle is not a snake - it is classified as a suborder of lizards, although it does not have limbs; It is precisely because of the duality of the appearance and internal structure of the animal that zoologists distinguish it into a special family. Like all lizards, it drops its tail in times of danger, which is why it was given the scientific name “brittle spindle.” For the same reason, the people believed that she, supposedly even cut in half, could live in peace and health. But look at the body of the spindle when it is in a calm state - right in the middle legless lizard is divided by a clearly visible constriction - the boundary between the body and the tail, along the line of which it is thrown (Fig. 20).

The spindle on the dorsal side is colored brownish-brown or dark gray with a characteristic bronze tint. This makes it very similar in color to the copperhead; Maybe that's why they are often confused? The sides and belly of the spindle are much lighter - they are white or yellow; However, there are single-colored males with two rows of large blue or, less commonly, black-brown spots on the back.

The spindle lives mainly in the middle zone of the European part of the USSR; to the east it reaches only Sverdlovsk region. Although there are always quite a lot of them in deciduous and mixed forests with well-developed litter, due to their secretive lifestyle, people rarely come across the spindle. It feeds on slugs, centipedes, insects, and earthworms; The spindle usually “twists” the latter out of the burrows, grasping the prey with its sharp teeth, stretching out its entire body and quickly rotating around its axis. Apparently, this is how the animal got its name.

Real lizards, as we know, have limbs; There are two species of these in our region - quick and viviparous. Both of them usually do not exceed 6-7 centimeters in length. At the same time, the body color of the sand lizard varies from yellowish-brown to bright green. But the viviparous lizard most often has a brown, gray-green or brown color. In addition, on the back of the latter there is always a pattern that does not exist on the quick-footed one: a dark, often intermittent stripe along the ridge, on the sides of it there are two light lines, and on the sides of the body there are dark wide stripes. In the fast one, there are only one or two dark lines running along the back (Fig. 21, 22).

The sand lizard is the more southern species of the two; east of Baikal and north of latitude She doesn’t come to Leningrad. On the contrary, the viviparous lizard clearly gravitates towards colder areas; its range stretches from the Baltic states to Sakhalin; in the north it reaches the coast Barents Sea, But south of latitude Saratov is not found anywhere. In connection with such a habitat, this species acquired the ability to give birth to viviparity; It’s just that during the short summer of the polar tundra and taiga, the eggs of this animal would not have time to develop young.

If sand lizard- the most numerous and common reptile of the region, preferring dry, well-warmed by the sun places in the steppes, along river valleys, on the slopes of ravines and gullies, the viviparous, on the contrary, is extremely rare in our country. For example, V.G. Over eight years of observations, Barinov encountered only seven specimens of this species. The viviparous lizard loves deciduous and coniferous forests, where it lives near swamps, peat bogs, clearings, burnt areas, along the edges and river banks. V.M. Shaposhnikov reports that it exists in similar places Zhigulevsky Nature Reserve, mainly near the former village of tar, as well as in the Racheysky and Muransky forests.

Very close to the mentioned species is the multi-colored foot-and-mouth disease, a reptile of the south of the country - Kazakhstan, Central Asia, the northern Caucasus and the Black Sea region (Fig. 23).

Academician A.G. Bannikov does not indicate foot-and-mouth disease for areas north of the Greater Irgiz basin. However, Samara herpetologists have repeatedly found it on the Samara Luka and in the Buzuluksky forest: in general, the multi-colored foot-and-mouth disease prefers sandy beaches, sea dunes and river valleys with sparse vegetation for permanent residence.

Foot-and-mouth disease got its name from its extremely variegated coloration; Most often, white and black spots and stripes with a correspondingly light or dark border are scattered along its back on an olive, brown or greenish background.

Finally, in conclusion of this chapter, it should be said about the most original (based on the shape of the body) of our reptiles - the marsh turtle, the only species of this order in our region. Nowadays it is perhaps the rarest of all reptiles in the Samara region. In general, the habitat of the marsh turtle in the USSR is limited only to southern Europe; It does not go east of Ufa and north of the Samara-Voronezh-Minsk-Kaliningrad line (Fig. 24).

This turtle usually lives in swamps, ponds, lakes of the coastal part of the Volga and Samara, small rivers and even canals. She almost never goes far from the reservoir; In case of danger, a turtle is capable of staying under water for a very long time and even burying itself at the bottom. The turtle's food is aquatic mollusks and insects, tadpoles, but it also loves plants.

The number of turtles in our region is falling catastrophically quickly every year; this is mainly due to the destruction of convenient places for its habitat, as well as for laying eggs; In addition, in places convenient for turtles, the disturbance factor increases every year. This happens for many reasons: due to the continuous development of river coastlines by departmental recreational institutions, due to the flooding of sandy beaches where turtles laid eggs with the waters of reservoirs, destruction of beaches during sand mining, and, of course, due to direct catching and destruction of animals by people.

According to V.M. Shaposhnikov, individual specimens of the marsh turtle were recorded in the floodplains of the Sok, Kondurcha, Samara, Bolshoi Irgiz rivers, on the Volga islands of Vasilyevsky and Proran, and also in the Chapaevsky mouth. In past years, these animals were also observed on the Volga near the village of Vinnovka.

...Well, even if a frog, snake or lizard is not very cute, but, in the end, it’s not their fault. This is how they were born, and it is this appearance that makes them best adapted to specific habitats. After all, any form of life created by the great master - nature, in itself is worthy of existence, regardless of our like or dislike for it. And this fully applies to the green frog, and the snake, and the fast lizard.

Valery EROFEEV.

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Turtles, crocodiles, lizards, snakes... Did you know that they are all reptiles, like the long-extinct dinosaurs? Their skin is covered with scales, plates or shell. And unlike mammals or birds, their body temperature changes depending on the temperature of the environment.

Almost all reptiles are carnivores. Their jaws have many teeth, which are needed to grab prey, and not chew or tear it apart: they swallow it whole. In most species, females lay eggs, which later hatch into young. But there are also ovoviviparous: the young hatched in the mother’s body are born without a shell, like a viper.

In the modern era, there are about 6,000 species of reptiles, living mainly in hot countries (crocodiles, many snakes). Those who have adapted to a colder climate (lizards and especially snakes) are forced to spend the winter in a state of torpor, hibernation. Except for some aquatic species (sea ​​turtles and snakes of the Indian and Pacific Oceans), reptiles, as a rule, are homebodies and do not move far from their territory. And they very rarely show a desire to live in a pack.

Amphibians

Amphibians, or otherwise amphibians, as their name indicates, divide their lives between two environments: water and land. They breed in water, where females lay eggs, from which tadpoles hatch. These herbivorous babies with a large head, which is immediately followed by a long tail, breathe through gills and lead an aquatic, “fishy” lifestyle.

Double life

While developing, the tadpole goes through several successive stages. First, its legs grow (the hind legs, then the front ones), then the tail disappears, and finally the gills are replaced by lungs. The animal becomes an adult and begins to breathe air, but continues to spend part of its life in water: there it reproduces.

Amphibians are divided into three groups: The first, most primitive, includes legless amphibians. similar to earthworms. Then come the anurans; their adult individuals do not have a tail: frogs, tree frogs, toads. And finally, the tailed ones, which do not lose their tails with age. These include black and yellow salamanders and newts, which differ from the former in brighter colors. Like reptiles, the body temperature of amphibians is variable. They are distributed mainly in hot and temperate areas.

Balkan turtle- length (shell) from 10 to 20 cm

Chameleon- length from 10 to 80 cm

Elephant turtle- length (shell) 1.2 m

Green lizard- length from 20 to 35 cm

Sea turtle- length (shell) from 1.3 to 1.9 m

Medyanitsa- length from 30 to 45 cm

Caiman- length from 1.5 to 4.5 m

Varan- length from 20 cm to 4 m

Alligator- length from 4 to 6 m

Nile crocodile- length from 5 to 9 m

Giant salamander- length 1.5 m

Python- length from 4 to 10 m

Already ordinary- length from 50 to 70 cm

Crested newt- length 15 cm

Viper- length 55 cm

Green frog- length from 5 to 12 cm

Axolotl- length 20 cm

tree frog- length 5 cm

Common toad- length from 7 to 15 cm

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 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 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 innate unconditioned ones, they also develop conditioned reflexes. Digestive, excretory and circulatory system open at 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 among aquatic inhabitants, 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 - long-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. By structure 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