Class amphibians: the rarest and strangest representatives. Who are amphibians Essential features of amphibians

Amphibious amphibians

(amphibians), a class of vertebrates. The skin is naked, rich in glands. Heart with 2 atria and 1 ventricle. Amphibians are the first vertebrates to switch from an aquatic to an aquatic-terrestrial lifestyle. Larvae breathe with gills, adults with lungs. Caviar is laid in water, some are viviparous. Development with transformation (metamorphosis). Body temperature is unstable (heterothermic animals). 3 modern orders: legless, tailed and tailless; over 3400 species. Most amphibians destroy pests of forestry and agriculture. Fossil amphibians are numerous, the main branch being the labyrinthodonts. 41 species and subspecies in the IUCN Red List.

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Amphibians, or Amphibians Scientific classification ... Wikipedia

Amphibians (Amphibia), a class of terrestrial vertebrates that usually retain the aquatic larval stage in ontogeny; b. or m. close connection with the aquatic environment is characteristic of most species 3. and in adulthood. 3. descended from ancient lobe-finned fish in ... ... Biological encyclopedic Dictionary

- (amphibian) class of vertebrates. The skin is naked, rich in glands. Heart with 2 atria and 1 ventricle. Amphibians are the first vertebrates to switch from an aquatic to an aquatic-terrestrial lifestyle. Larvae breathe with gills, adults with lungs. Caviar… … Big Encyclopedic Dictionary

AMPHIBIAN, oh, oh. Dictionary Ozhegov. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Explanatory dictionary of Ozhegov

- (or Amphibians, Amphibia) a class of vertebrates, cold-blooded animals (i.e., not having a constant body temperature), with bare skin for the most part without scales, breathing in the adult state with gills and lungs, or only lungs (as well as skin), in ... ... Encyclopedia of Brockhaus and Efron

It seems to almost all of us that we can define any concept from the program without any problems. secondary school. For example, amphibians are frogs, turtles, crocodiles and similar representatives of the flora. Yes, it's true. We can name some of the representatives, but what about describing them? characteristic features or lifestyle? For some reason, they were singled out in a special class? What is the reason? And what is the rule? Here with it, you see, it is more difficult.

How will they surprise us?

It is likely that amphibians differ from similar internal arrangements, say, mammals or reptiles. But what? Are there similarities between us and them? We will try to answer all these questions in this article. However, it is worth paying attention to the fact that in the process of studying the material, the reader will not only learn about how amphibians are similar to each other (turtles and crocodiles, by the way, do not belong to them), but also get acquainted with the most interesting facts associated with these animals. We bet you didn't even know something. Why? The thing is that a paragraph of a school textbook does not always provide the entire necessary range of knowledge.

General information about the class

The class Amphibians (or Amphibians) represents the primitive ancestors of which more than 360 million years ago changed their habitat and left the water for land. Translated from ancient Greek the name translates as "living a double life."

It should be noted that amphibians are cold-blooded creatures with a variable body temperature, depending on external conditions a habitat.

In the warm season, they are usually active, but when cold weather sets in, they hibernate. Amphibians (frogs, newts, salamanders) appear in the water, but spend most of their existence on land. This feature can be called almost the main one in the life of this variety of living beings.

Amphibian species

In general, this class of animals includes more than 3,000 species of amphibians, represented by three groups:

• caudate (salamander);
• tailless (frogs);
• legless (worms).

Amphibians appeared in places with a temperate and hot climate. However, to this day they live there.

Basically, they are all small in size and have a length of no more than one meter. The exception is (the main signs of amphibians are, as it were, blurred), living in Japan and reaching a length of up to one and a half meters.

Amphibians spend their lives alone. Scientists have established that this did not happen as a result of evolution. The first amphibians led exactly the same way of life.

Among other things, they perfectly camouflage by changing their color. By the way, not everyone knows that poison secreted by special skin glands also serves as protection against predators. Perhaps only reptiles, arthropods and amphibians have this feature. Mammals with such a set of characteristic features are not found in nature. In fact, it is even difficult to imagine how, for example, a cat familiar to all of us could adjust the temperature of its own body depending on changes in the environment or secrete poison, defending itself from a dog attacking it.

Features of the skin

All amphibians have a smooth, thin covering of skin rich in skin glands that secrete mucus necessary for gas exchange.

The secreted mucus also prevents the skin from drying out and may contain toxic or signaling substances. The multi-layered epidermis is abundantly supplied with a network of capillaries. Most venomous individuals can take bright colors, serving as a protective and warning device against predators.

In some amphibians of the anurans group, keratinized formations are found on the upper layer of the epidermis. This is especially developed in toads, in which more than half of the skin surface is covered with a stratum corneum. It is important to note that the weak keratinization of the cover does not prevent the penetration of water through the skin. This is how the breathing of amphibians is arranged, which are able to breathe under water only with their skin.

In terrestrial species, keratinized skin can form claws on the limbs. In tailless amphibians, the entire subcutaneous space is occupied by lymphatic lacunae - cavities where a supply of water accumulates. And only in a few places is the connective tissue of the skin connected to the muscles of the amphibian.

Lifestyle of amphibians

Amphibians, photos of which can be found in all zoology textbooks without exception, undergo several stages of development: those born in water and resembling fish, as a result of transformation, acquire pulmonary respiration and the ability to live on land.

This development is not found in other vertebrates, but is common in primitive invertebrates.

They occupy an intermediate position between aquatic and terrestrial vertebrates. Amphibians live (fish in this regard are more adapted representatives of the fauna) in all parts of the world where there is freshwater, with the exception of cold countries. Most of them spend half their lives in water. In others, adults live on the ground, but in places with high humidity and near water.

During a drought, amphibians (birds might envy such a feature) fall into suspended animation, burrowing into the silt, and in cold weather in areas with temperate climate hibernating.

The most favorable habitats are tropical countries with wet forests. Least of all, amphibians prefer arid corners of nature ( Central Asia, Australia, etc.).

These are aquatic and terrestrial inhabitants, who usually prefer the night. The day is spent in shelter or half asleep. Tailed species move on the ground similarly to reptiles, and tailless species move in short jumps.

Amphibians are animals that are generally able to climb trees. Unlike reptiles, adult male amphibians are very vociferous; in their youth they are silent.

Nutrition in most cases depends on age and stage of development. The larvae eat plant and animal microorganisms. As they grow older, the need for live food appears. These are already real predators, feeding on worms, insects and small vertebrates. During the heat, their appetite increases. The inhabitants of the tropics are much more voracious than their relatives from countries with a temperate climate.

At the beginning of life, amphibians, whose photos adorn atlases that clearly show the evolution of human development, develop rapidly, but over time their growth slows down greatly. The growth of frogs continues up to 10 years, although they reach maturity by 4-5 years. In other species, growth stops only by the age of 30.

In general, it should be noted that amphibians are very hardy animals that can endure hunger no worse than reptiles. For example, a toad planted in a damp place can go without food for up to two years. The respiratory system of amphibians continues to function fully.

Amphibians also have the ability to regenerate lost body parts. However, in highly organized amphibians, such properties are less pronounced or absent altogether.

Like reptiles, amphibians also heal quickly. Tailed species are distinguished by special survivability. If a salamander or a newt is frozen in water, then they fall into a stupor and become brittle. As soon as the ice melts, the animals come back to life. It is necessary to remove the newt from the water, it instantly shrinks and does not show signs of life. Put it back - and the triton immediately comes to life.

The body shape and skeletal structure are similar to those of fish. The brain consists of two hemispheres, the cerebellum and the midbrain, and has a simple structure. The spinal cord is more developed than the brain. The teeth of amphibians serve only to capture and hold prey, but are not at all adapted for chewing it. The respiratory and circulatory systems are of great importance for the life of amphibians. They have cold blood like reptiles.

By appearance and lifestyle amphibians (turtles, we recall, do not belong to them, although sometimes they lead a similar lifestyle) are divided into three groups: tailless, tailed and legless. Anurans include frogs, which are distributed throughout the world, where there is moisture and enough food. Frogs love to sit on the shore and bask in the sun. At the slightest danger, they rush into the water and burrow into the silt.

Representatives of such a huge group of animals as the class Amphibians are good swimmers. With the approach of cold weather, amphibians hibernate. Spawning occurs in the warm season. The development of eggs and tadpoles is fast. Their main food is plant and animal food.

Look like lizards. They live in water bodies or near water. They are nocturnal and hide in shelters during the day. Unlike lizards, they are clumsy and slow on land, but very agile in water. They feed on small fish, mollusks, insects and other small animals. This species includes salamanders, newts, proteas, cryptogills, etc.

The order of legless amphibians includes caecilians, which have an external resemblance to snakes and, however, in terms of development and internal structure they are close to salamanders and proteas. Worms live in tropical countries(except Madagascar and Australia). They live underground, making passages. They lead the same lifestyle as earthworms that make up their diet. Some worms bring viviparous offspring. Others lay their eggs in the soil next to or in water.

The benefits of amphibians

Amphibians are among the first and most primitive, occupying a special place in the evolution of terrestrial vertebrates, which is the least studied.

For example, the role of birds and mammals in human life has long been known. In this regard, amphibians are very far behind. However, they also have great importance in economic activity person. As you know, in many countries, frog legs are considered delicacies and are highly valued. For these purposes in Europe and North America about a hundred million frogs are harvested annually. This indicates that amphibians are also of economic importance.

Adults feed on animal food. Eating harmful insects in gardens, orchards and fields, they benefit humans. Among insects, mollusks or worms, there are also carriers of dangerous various diseases.

Amphibians that feed on aquatic microorganisms are considered less useful. Tritons are an exception. And although the basis of their food includes aquatic organisms, they also eat mosquito larvae (including malaria), which breed in reservoirs with warm and stagnant water.

The benefits of amphibians largely depend on their number, seasonal, food and other characteristics. All these factors affect the nutrition of amphibians. For example, living in water bodies, it is more useful than its relatives living in other places.

Unlike birds, amphibians exterminate a greater number of insects that have deterrent and protective functions that birds do not eat. Also, land species of amphibians feed mainly at night, when many insectivorous birds sleep.

The full significance of amphibians in human life can only be appreciated by a sufficient study of these animals. At present, the biology of amphibians has an extremely superficial knowledge.

Amphibians as an important part of the food chain

In some fur-bearing animals, most amphibians are the main food. For example, the survival of a raccoon dog in different habitats directly depends on the abundance of amphibians in these areas.

Mink, otter, badger and black polecat willingly eat amphibians. Therefore, the number of these animals is significant for hunting grounds. Amphibians are included in diet and other predators. Especially when there is not enough basic food - small rodents.

In addition, valuable commercial fish in winter, they feed on frogs in reservoirs and rivers. Most often, their prey is the grass frog, which, unlike the green frog, does not burrow into the silt for wintering. In summer, it eats terrestrial invertebrates, and in winter it goes to winter in the lake. Thus, the amphibian becomes an intermediate link and replenishes the food base for fish.

Amphibians and science

Due to their structure and survivability, amphibians began to be used as laboratory animals. It is on the frog that the largest number of experiments are carried out, ranging from biology lessons at school to major medical research by scientists. For these purposes, more than tens of thousands of frogs are used annually as biological material in laboratories. It is possible that this can lead to the complete extermination of animals. By the way, in England catching frogs is prohibited, and they are now under protection.

It's hard to list everything scientific discoveries associated with experiments and physiological experiments on frogs. Recently, their use has been found in laboratory and clinical practice for the early diagnosis of pregnancy. The introduction of the urine of pregnant women into male frogs and toads causes a rapid process of spermatogenesis in them. In this regard, the green toad stands out in particular.

The most unusual amphibious planets

Among the little-studied species of these animals, there are many rare and unusual specimens.

For example, ghost frogs (genus Heleophryne) are actually the only family of anurans with only six species, one of which is found only in the cemetery. Apparently, that's enough from here. unusual name kind. They live mainly in the northeast of South Africa near forest streams. They have sizes up to 5 cm and camouflage color. They are nocturnal and hide under rocks at night. True, today two species are almost exterminated.

Proteus (Proteus anguinus) is a tailed species of the class Amphibians living in underground lakes. Reaches a length of up to 30 cm. All individuals are blind and have transparent skin. Proteas hunt thanks to the electrical sensitivity of the skin and the sense of smell. They can live without food for up to 10 years.

The next representative, the Gardner zooglossus frog (Sooglossus gardineri) belongs to one of the unusual tailless species of the Amphibian family. It is under threat of destruction. It has a length of not more than 11 mm.

Darwin's frog is a fairly small, tailless amphibian that lives in cold mountain lakes. The body length is about 3 cm. Males carry their offspring in a throat pouch.

• Even far from all avid travelers are aware that there are many cafes in the state of Peru where special frog cocktails are prepared. It is believed that such drinks relieve many diseases, treat asthma and bronchitis, and help restore potency. One way to prepare it is to grind a live frog in a blender with the addition of bean soup, honey, aloe juice and poppy root. Are you ready to dare and try this dish?
• Unusual amphibians live in South America. Paradoxical frogs decrease in size as they grow older. The usual length of an adult reaches only 6 cm. However, their tadpoles grow up to 25 cm. A strange feature.
• During experiments on laboratory frogs, Australian researchers made an accidental discovery. They found that these animals are able to remove foreign bodies from their body through the bladder. Experienced and very eminent scientists implanted transmitters in animals, which after a while moved into their bladders. Thus, it turned out that when foreign objects enter the body of amphibians, they gradually become overgrown with soft tissues and are drawn into the bladder. This discovery actually revolutionized the scientific field.
• Few ordinary people are aware that the reason for the frequent blinking of frogs while eating is pushing food down the throat. Animals are not able to chew food and push it with their tongue into the esophagus. When blinking, the eyes are pulled into the skull by special muscles and help push food through.
• A very interesting specimen is the African frog Trichobatrachus robustus, which has an amazing adaptation to protect itself from enemies. At the moment of threat, her paws pierce the subcutaneous bones, forming a kind of "claws". After the danger has passed, the "claws" retract and the damaged tissue regenerates. Agree, not every representative of the modern fauna can boast of having such a useful and unique feature.

Amphibians are a class of primitive chordates. Amphibians in the evolutionary line are between water and land creatures, since birth and maturation take place in water, and mature life activity takes place on land. In the second grade of the school, we are introduced to amphibians. List (Grade 2, textbook " The world”) representatives of the amphibian class: toads, frogs, newts and salamanders. You need to add a worm to the list.

Science classifies these animals into orders:

• frogs and toads are tailless;
• newts and salamanders are tailed;
• worms are legless.

Today, 7711 species of the amphibian class are known, which are distributed on all continents, with the exception of Antarctica.

Origin and evolution

In the Devonian period (400 million years ago), all the conditions were formed on the earth for the development of land by fish. Hot and humid climate, the abundance of food supply allowed lungfish to come ashore. Later, they evolved into ichthyostegids, which are an evolutionary link between lobe-finned fish and amphibians.

On land, animals change their fins into paws. Gills disappear and lungs form. At the same time, other systems of the body also evolve, which finally leads to the appearance of a class of amphibians. In the Carboniferous, an ancient subclass of lepospondyls appears. Amphibians appeared in the Mesozoic. In the process of evolution, animals repeatedly returned to the aquatic environment and lost limbs. As a result, such a variety of species has arisen.

General characteristics and signs

All representatives of amphibians have thin and smooth skin, which contributes to the diffusion of air through the skin. The skin of amphibians consists of corium and superficial epidermis. It has a large number of glands that secrete mucus, which promotes self-defense and respiration. Mucus can cover the entire body. The body consists of a head, torso, limbs (not found in worms) and, in some representatives, a tail (salamanders and newts). Depending on the species, the animal has from seven to two hundred vertebrae. Amphibians have segmented trunk muscles.

Most representatives of the class have lungs, but they can also breathe through the skin, and tadpoles have gills. These creatures are cold-blooded, have a three-chambered heart, a closed circulatory system and 2 circles of blood circulation. All amphibians are predators that feed on insects and fry. Food is swallowed whole, since the teeth perform only a grasping function. They hunt with the help of the tongue, which they shoot at the victim.

Developed nervous system- the result of landfall. It is a known fact that the brain of an amphibian is 4 times larger than that of fish, in some species - 10 times. The eyes of amphibians are similar in structure to the eyes of fish, but adapted for earth's atmosphere and have differences. Some species have eyelids and color vision. They have a developed hearing aid.

Reproduction of amphibians

Amphibians are bisexual animals that reproduce in water. The female throws eggs into the aquatic environment, and the male fertilizes. The egg develops over 1 to 3 weeks. After that, a larva appears, which in structure resembles a fish fry. Further development of the tadpole also occurs in the reservoir. The next stage is the transformation into an adult and access to land. Some species lay their eggs on the ground, others carry them on themselves.

Modern types of amphibians

Among amphibians, the following types are distinguished:

The first land inhabitants are amphibians, which occupy an important niche in the earth's ecosystem. They destroy a huge number of harmful insects, and they themselves are food for many animals. How much one toad destroys pests? Several thousand during the year. Whatever the bias regarding amphibians, it must be remembered that they are very useful to humans. And also they are often used in laboratories as samples. In many countries, these creatures are protected: this happened thanks to reports and reports of scientists.

The head has a pair of nostrils for breathing. There are eyes, they can be protected by eyelids. There is a mouth. The skin is bare, moistened with mucus. Amphibians can breathe with their lungs as well as with their skin. Some species have gills.

The body temperature of these animals depends on the temperature environment, so they are active only in warm weather. When the temperature drops, they immediately fall into a stupor. Meet in nature and poisonous individuals.

Amphibians reproduce like fish by laying eggs. The eggs are not protected by shells or skin, so amphibians usually breed in water. From the eggs of amphibians, a larva emerges, which looks very similar to a fish. Further development takes place in water with transformation - metamorphoses. Metamorphosis- this is a deep transformation of the structure of the body, transformation. Then future amphibians lose their gills, some individuals even their tail. Then they grow limbs and go to land in the form of an adult animal.

Amphibians feed exclusively on mobile living food. They destroy a huge number of insects and their larvae. They are found everywhere, excluding only too cold or hot zones of the Earth.

The most ancient and survived to our times due to their underground lifestyle are legless amphibians. There are about 150 species of them in nature. These include all tropical and very many aquatic worms. These amphibians are distinguished by their unusual body structure. These amphibians have a worm-like cylindrical body. The skin is naked, equipped with mucous poisonous glands. There are transverse rings, like earthworms. Animals do not have limbs or a tail. Their head is strong, small, imperceptibly passes into the body. With it, the worms lay their dungeons in the damp earth. In connection with the burrowing lifestyle, the eyes were under their skin. Amphibians find food using their sense of smell and touch. They eat snails, worms, larvae, insects. They lead a very hidden lifestyle, do not like sunlight. The most famous is the ringed worm (Fig. 2).

Rice. 2. Ringed worm ()

Unlike other amphibians, they lay their eggs on land. The female curls up around the clutch of eggs and moistens it with her mucus, incubates.

The fish snake has small inconspicuous bony scales in the skin (Fig. 3).

Rice. 3. Fish snake ()

The Central American worm does not lay eggs, it immediately gives birth to live cubs.

Science knows about 350 species tailed amphibians. These animals look like lizards, only the skin is soft and completely devoid of scales. Tailed amphibians include newts, salamanders. These animals have an elongated spindle-shaped body, which imperceptibly passes into a long tail. Curving the tail to the right and left helps to move in the water. On land, amphibians move with the help of two pairs of underdeveloped limbs. The fingers may be webbed and devoid of claws.

Sirens have only forelimbs (Fig. 4).

Amphibians, constantly living in water, breathe with gills. There is a tongue in the mouth, its shape is diverse. There are small teeth. Many caudates have the ability to grow a new one if they lose a tail or leg. Amphibians do not know how to chew, they swallow food whole. Amphibians grab everything that moves and do not take completely edible motionless food. Tailless amphibians feed on insects, grabbing them in motion with a long sticky tongue. Tailed birds feed on worms and arthropods.

Legless amphibians find food by touch or use the sense of smell. They feed on insect larvae and worms.

The Siberian salamander is one of the few amphibians that is not afraid to live in permafrost conditions (Fig. 5).

Rice. 5. Siberian salamander ()

The most well-known tailed amphibian is the triton (Fig. 6). They look like little dragons. Tritons love to hunt at night.

The fire salamander is famous for its bright color (Fig. 7). It is interesting that the shape, size, pattern on the body of salamanders is unique for each individual.

Rice. 7. Salamander ()

The axolotl looks like an adult larva (Fig. 8).

Rice. 8. Axolotl ()

In nature, there is the most numerous order of amphibians - this is tailless amphibians. There are about 3 thousand species of them. This is the most known to man detachment. These include toads, frogs, tree frogs, toads, and spadefoot. Their body is short and squat. The head is wide, without a neck, passes into the body. There is no tail. The skin is bare, moisturized with secrets. On the head are a pair of movable eyes. Amphibians use their eyesight to find prey. There are a pair of nostrils. The forelimbs are shorter than the hind ones. They have membranes that help them swim. On the ground, amphibians jump, they lead active image life. Small teeth and a sticky tongue that folds in the mouth help them catch prey.

The bullfrog is a predator (Fig. 9). She even attacks chickens and eats young ducklings. Her cry resembles the roar of a bull.

Rice. 9. Bullfrog ()

The Surinam pipa is famous for carrying tadpoles in cells on its back (Fig. 10). Adult frogs emerge from them.

Rice. 10. Surinam pipa ()

The hairy frog defends itself with sharp claws, like a cat's (Fig. 11).

Rice. 11. Hairy frog ()

The tiny Colombian frog (Fig. 12) fits in a teaspoon, and its poison is the most powerful of animal poisons.

Rice. 12. Colombian frog ()

Flying frogs deftly jump from trees, spreading their membranes (Fig. 13). This helps them stay in the air.

Rice. 13. Flying frogs ()

Amphibians play big role in human life. They destroy a huge number of insects, thereby benefiting agriculture. They also eat insects that carry disease. Amphibians are also used in medical laboratory research. Man even breeds amphibians as a pet. In some countries they are even eaten.

Bibliography

1. Samkova V.A., Romanova N.I. The world around 1. - M .: Russian word.
2. Pleshakov A.A., Novitskaya M.Yu. The world around 1. - M .: Education.
3. Gin A.A., Faer S.A., Andrzheevskaya I.Yu. The world around 1. - M .: VITA-PRESS.

1. Worldofnature.ru ().
2. Floranimal.ru ().
3. Zoodrug.ru ().

Homework

1. Who are amphibians?
2. How do amphibians reproduce?
3. What are the three orders of amphibians? Describe each order of amphibians.
4. * Prepare a story about the most unusual and interesting, in your opinion, representative of the Amphibian class.

• Toads, frogs, newts and their other relatives are representatives of a very curious class of the animal world - amphibians.

• Triton

  Triton
• Translated from Greek, this word means - leading a double lifestyle. Indeed, water and land are home to amphibians - both in the water and on the ground. This is where their second name comes from. amphibians.
• In appearance and lifestyle, amphibians are very similar to reptiles, and on the other hand to fish.
• Ancient peoples treated these animals in different ways - it happened positively and sometimes it was quite the opposite. Many ancient tribes associated frogs and toads with good harvests and rebirth. This is due to their annual disappearance for the winter and the appearance during the awakening of nature.
• The connection of frogs with water element and underworld reflected in the myths of many peoples in all parts of the world. Our ancestors believed that it holds the world on its back and is connected with the roots of the "world tree". Such myths were transmitted not only in southern countries, where there are especially many of these animals, but also among the Siberian peoples of our Russia.
• People believed that frogs were created by God to purify poisoned water, they put frogs in a jug of milk so that it would not turn sour.

• Frog

  
  Frog
• Frogs were also used in medicine and witchcraft among a number of tribes. South America and Africa. In Siberia, images of frogs were used by shamans to exorcise an evil spirit, and the poisons of the amphibian toad - agi and poison dart frogs - were used by local tribes of America to poison arrows when hunting and in war.
• HISTORY OF ORIGIN.
• happened amphibians the following way.
• Many groups of fish lived in freshwater lakes, but during droughts, the reservoirs dried up, and the fish ended up on land and became dehydrated.
• Those of them that could survive without water until a new rain could survive. Over time, fish appeared with light and muscular fins, which gave them the ability to crawl on the ground. This is how amphibians arose - animals that need water only for reproduction and further larval development.
• CHARACTERISTICS OF Amphibians.

• Salamander

  
  Salamander
• The body shapes of amphibians differ from each other: tailed amphibians look more like fish, tailless ones have a rounded or flat body, and some are completely devoid of limbs and look more like worms than vertebrates.
• Previously, amphibians were called naked reptiles, and indeed, they have neither scales, like fish, nor feathers, like birds, nor wool, like mammals; most of the amphibians are covered with bare skin. But in this skin there are glands that other vertebrates do not have.
• The color of some amphibians can change, like chameleons.
• Both in the upper layer of the skin and in the inner layer of all amphibians there are a lot of glands of various sizes and purposes.
• The most interesting are the poisonous glands, which are located in the lower layer of the skin, have an oval or spherical shape and secrete a mucous fluid in which the poisonous substance is located. It is clear that poison is needed to protect against enemies.
• It has now been established that the venom of amphibians is very strong, but it is not dangerous for humans and large animals, because. contained in small quantities.
• Elastic and very thin skin is of great importance in the life of amphibians: they do not drink water, but absorb it through their skin.
• That is why they need the proximity of water or humidity. Frogs that are far from water bodies quickly lose weight, become lethargic, and may even die.
• If a wet rag is applied to such a "dehydrated" frog, then it begins to cling to it with its body and quickly comes to its senses.
• Gas exchange also takes place through the skin. In a closed tin can, a frog, surrounded by a humid atmosphere, can live for 20 days if the access of air to the lungs is stopped.

• frog development

  frog development
• The development of embryos occurs in the same way as in fish: eggs are laid in water in the form of caviar, and then fertilized by males.
• It is not a small frog that hatches from the egg, but a tadpole larva and goes through several stages of development.
• This development is called development with transformation, which lasts rather quickly (4 months), and after that the frog grows very slowly and only in the fifth year reaches its present size.
• live amphibians only in fresh water.
• You can find out about other inhabitants of fresh water.
• Some spend their entire lives in the water, others settle on land, although they always stay near water or in wet places.
• If winter or drought comes, they prefer to hibernate and wait out hungry and cold times, burrowing into the silt.
• Most amphibians are nocturnal, from sunset to morning. During the day they crawl into shelters and sit motionless, others enjoy the warmth of the sun and spend the day half asleep.
• Amphibians feed differently depending on their age: the larvae eat plants and small animals, while adults are already real predators and pursue all animals that they can swallow.