What helps animals survive adverse conditions. Ways of experiencing adverse conditions by living organisms (wintering, hibernation, suspended animation, migration, etc.)

Sections: Biology

Goals: increase the areas of knowledge of students; learn to analyze the phenomenon of temporary cessation of vital activity in living organisms, using it as a means to adapt and survive in adverse conditions.

Equipment: tables of molluscs, crustaceans, insects, fish, amphibians, reptiles, birds, mammals.

The winter season is unfavorable for many representatives of the animal and plant world, both due to low temperatures and a sharp decrease in the ability to get food. In the course of evolutionary development, many species of animals and plants have acquired peculiar adaptive mechanisms in order to survive in an unfavorable season. In some species of animals, the instinct to create food reserves has arisen and established itself; others have developed another adaptation - migration. Strikingly long flights of many species of birds, migration of some species of fish and other representatives of the animal world are known. However, in the process of evolution in many species of animals, another perfect physiological mechanism of adaptation was noticed - the ability to fall into a lifeless state at first glance, which manifests itself differently in different species of animals and has different names (anabiosis, hypothermia, etc.). Meanwhile, all these conditions are characterized by inhibition of the body's vital functions to the minimum that allows it to survive adverse conditions. winter conditions without eating. Such a state of imaginary death falls into those species of animals that are not able to provide themselves with food in winter and for them there is a danger of death from cold and hunger. And all this, developed in the process of evolution, is subject to strict natural expediency - the need to preserve the species.

Hibernation is a widespread phenomenon in nature, despite the fact that its manifestations are different in representatives of certain groups of animals, whether they are animals with unstable body temperature (poikilothermic), also called cold-blooded, in which the body temperature depends on the ambient temperature, or animals with a constant body temperature (homeothermic), also called warm-blooded.

From among animals with unstable body temperature, various types of mollusks, crustaceans, arachnids, insects, fish, amphibians and reptiles fall into a state of hibernation, and from animals with a constant body temperature, several species of birds and many species of mammals.

How do snails hibernate?

From the soft-bodied type, many types of snails fall into hibernation (for example, all land snails). Encountered garden snails hibernate in October, and it lasts until early April. After a long preparatory period, during which they accumulate the necessary nutrients in their bodies, the snails find or dig minks so that several individuals can winter together deep underground, where the temperature will be maintained at 7 - 8 ° C. Having clogged the minks well, the snails descend to the bottom and lie with the shell opening up. They then close this hole, releasing a slimy substance that soon hardens and becomes elastic (film-like). With a significant cold snap and a lack of nutrients in the body, snails burrow even deeper into the ground and form another film, thus creating air chambers that act as an excellent insulator. It has been established that during a long wintering period, snails lose more than 20% of their weight, with the largest loss occurring in the first 25-30 days. This is due to the fact that all metabolic processes gradually fade in order to reach the minimum at which the animal falls almost into a state of suspended animation with barely perceptible vital functions. During hibernation, the snail does not feed, breathing almost stops. In the spring, when the first warm days come and the soil temperature reaches 8-10 ° C, when the vegetation begins to develop and the first rains fall, the snails come out of their winter shelters. Then begins intensive activity to restore exhausted food reserves in their body; this is expressed in the absorption of a huge amount of food compared to their body.

Water snails, pond snails, also fall into a state of hibernation - most of them burrow into the silt at the bottom of the reservoir in which they live.

Where do crayfish hibernate?

Everyone knows the threat popular among the people: "I'll show you where the crayfish hibernate!". It is believed that this proverb appeared during the time of serfdom, when the landowners, punishing the guilty serfs, forced them to catch crayfish in the winter. Meanwhile, it is known that this is almost impossible, since crayfish overwinter, deeply buried in holes at the bottom of reservoirs.

From the point of view of taxonomy, the class of crustaceans is divided into two subclasses - higher and lower crustaceans.

Of the higher crustaceans, river, marsh and lake crayfish fall into a state of hibernation. Males hibernate in groups in deep pits at the bottom, and females alone in minks, and in November they glue fertilized eggs to their short legs, from which ant-sized crustaceans hatch only in June.

Of the lower crustaceans, water fleas (genus Daphnia) are of interest. They lay, depending on the conditions, two types of eggs - summer and winter. Winter eggs have a strong shell and are formed when unfavorable living conditions occur. For some species of lower crustaceans, drying out and even freezing of eggs is a necessary condition for the continuation of their development.

Diapause in insects

By the number of species, insects surpass all other classes. Their body temperature depends on the environment, which has a strong effect on the speed of vital influences, and low temperatures greatly reduce this speed. At negative temperatures, the entire development of the insect slows down or practically stops. This anabiotic state, known as "diapause", is a reversible stoppage of developmental processes and is caused by external factors. Diapause occurs when conditions are unfavorable for life and continues throughout the winter, until conditions become more favorable with the onset of spring.

The onset of the winter season different types insects at different stages of their development, in which they hibernate - in the form of eggs, larvae, pupae or adult forms, but usually each individual species falls into diapause at a certain stage of its development. So, for example, seven-point ladybug winters as an adult.

It is characteristic that the wintering of insects is preceded by a certain physiological preparation of their body, consisting of the accumulation of free glycerol in their tissues, which does not allow freezing. This occurs at the stage of development of the insect in which they will overwinter.

Even with the onset of the first signs of a cold snap in autumn, insects find comfortable shelters (under stones, under the bark of trees, under fallen leaves in burrows in the soil, etc.), where, after a snowfall, the temperature is moderately low and uniform.

The duration of diapause in insects is directly related to the reserves of fat in the body. The bees do not fall into a long diapause, but still at a temperature of 0 to 6 ° C they become numb and can stay in this state for 7-8 days. At lower temperatures they die.

It is also interesting how insects accurately determine the moment when they should exit the anabiotic state. Scientist N.I. Kalabukhov studied anabiosis in some species of butterflies. He found that the duration of diapause in certain types different. For example, the peacock butterfly was in suspended animation for 166 days at a temperature of 5.9 ° C, while the silkworm needed 193 days at a temperature of 8.6 ° C. According to the scientist, even differences in the geographical area affect the duration of diapause.

Do fish hibernate?

In a peculiar way, some species of a large class of fish adapt to low water temperatures in winter. Normal body temperature in fish is not constant and corresponds to the temperature of the water. With a sudden sharp drop in water temperature, the fish fall into a state of shock. It is enough, however, that the water warms up, and they quickly “come to life”. Experiments have shown that frozen fish come to life only when their blood vessels are not frozen.

Originally adapted to low water temperatures in winter, some fish that live in Arctic waters: they change their blood composition. With a decrease in water temperature in autumn, salts accumulate in their blood in such a concentration that is typical for sea ​​water, while the blood freezes with great difficulty (a kind of antifreeze).

From freshwater fish back in November, carp, ruff, perch, catfish and others fall into hibernation. When the water temperature drops below 8 - 10°C, these fish move to the deeper parts of the reservoirs, burrow large groups in the silt and remain there in a state of hibernation throughout the winter.

Some sea ​​fish also tolerate severe cold in a state of hibernation. So, for example, herring already in autumn approach the coast of the Arctic Ocean in order to fall into a state of hibernation at the bottom of some small bay. The Black Sea anchovy also winters in the southern regions of the sea - off the coast of Georgia, at this time it is not active and does not consume food. And the Azov anchovy before the onset of the winter period migrates to the Black Sea, where it gathers in groups in a relatively sedentary state.

Hibernation in fish is characterized by their extremely limited activity, complete cessation of feeding, and a sharp decrease in metabolism. At this time, their body is supported by the reserves of nutrients accumulated due to abundant nutrition in the autumn.

hibernation of amphibians

In terms of lifestyle and structure, the class of amphibians is transitional between typically aquatic vertebrates and typically terrestrial animals. It is known that different kinds frogs, newts, salamanders also spend the unfavorable winter season in a state of stupor, as these are animals with unstable body temperature, which depends on the ambient temperature.

It has been established that the hibernation of frogs lasts from 130 to 230 days and its duration depends on the duration of winter.

In reservoirs, in order to overwinter, frogs gather in groups of 10-20 specimens, burrow into silt, into underwater depressions and other voids. During hibernation, frogs breathe only through their skin.

In winter, newts usually nestle under warm, rotten stumps and trunks of fallen trees. If they do not find such convenient "apartments" nearby, they are satisfied with cracks in the soil.

Reptiles hibernate too

From the class of reptiles, almost all species of our fauna fall into a state of hibernation in winter. Low winter temperatures are the main reason for this phenomenon.

Winter quarters are usually underground caverns or voids formed around large old stumps with rotten roots, crevices in rocks, and other places that are not accessible to their enemies. In such shelters, a large number of snakes gather, forming huge coils of snakes. It has been established that the temperature of snakes during hibernation almost does not differ from the ambient temperature.

Most species of lizards (meadow, striped, green, forest, spindle) also hibernate, burrowing into the soil, into burrows that are not threatened by flooding. On warm, sunny days in winter, lizards may “awake” and crawl out of their winter shelters for several hours to hunt, after which they again hide in their burrows, falling into a state of torpor.

Bog turtles spend the winter burrowing into the silt of the reservoirs in which they live, while terrestrial turtles climb to a depth of 0.5 m into the soil into some natural shelters or holes of moles, foxes, rodents, covering themselves with peat, moss and wet leaves.

Preparation for wintering begins in October, when turtles accumulate fat. In the spring, with temporary warming, they wake up, sometimes for a whole week.

Are there birds that hibernate in winter?

Most animals with unstable body temperature, which depends on the environment, fall into a state of hibernation. But surprisingly, many animals with a constant body temperature, such as birds, can also hibernate during the unfavorable seasons of the year. It is known that most birds avoid adverse winter conditions by migrating. Even Aristotle, in his multi-volume History of Animals, drew attention to the fact that “some of the birds fly away to spend the winter in warm countries, while others take refuge in various shelters, where they fall into hibernation.”

The great Swedish naturalist Karl Linnaeus also came to this conclusion, who in his work “The System of Nature” wrote: “In autumn, when the cold starts, swallows, not finding enough insects for food, begin to seek shelter for wintering in reed beds along the banks of lakes and rivers. ".

The torpor into which some species of birds fall is very different from the hibernation common to many mammals. First of all, the body of birds not only does not accumulate energy reserves in the form of fat, but, on the contrary, consumes a significant part of them. While mammals go into hibernation, having noticeably gained weight, birds lose a lot of weight before stupor. That is why the phenomenon of torpor in birds, according to the Soviet biologist R. Potapov, should be called not hibernation, but hypothermia.

Until now, the mechanism of hypothermia in birds is not fully understood. The fall of birds into a state of stupor under adverse living conditions is an adaptive physiological reaction that has been fixed in the process of evolution.

What mammals hibernate in winter?

As in the animals discussed earlier, so in mammals, hibernation is a biological adaptation to survive the unfavorable season of the year. Although animals with a constant body temperature usually tolerate cold climates, the lack of suitable food in winter has caused some of them to acquire and gradually consolidate in the course of evolution this peculiar instinct - to spend an unfavorable winter season in an inactive state of hibernation.

There are three types of hibernation according to the degree of torpor:

1) slight torpor, which easily stops (raccoons, badgers, bears, raccoon dogs);

2) complete stupor, accompanied by periodic awakenings only on warmer winter days (hamsters, chipmunks, bats);

3) real incessant hibernation, which is a stable, prolonged stupor (ground squirrels, hedgehogs, marmots, jerboas).

Winter hibernation of mammals is preceded by a certain physiological preparation of the organism. It consists primarily in the accumulation of fat reserves, mainly under the skin. In some winter sleepers, subcutaneous fat reaches 25% of the total body weight. For example, ground squirrels get fat at the beginning of autumn, increasing their body weight three times compared to spring-summer weight. Before hibernation, hedgehogs and brown bears, as well as all bats, get significantly fatter.

Other mammals, such as hamsters and chipmunks, do not accumulate large stores of fat, but store food in their shelter to use during their brief periods of awakening in winter.

During hibernation, all species of mammals lie motionless in their burrows, curled up into a ball. So it is best to keep warm and limit heat exchange with environment. Zimnik apartments of many mammals are natural emptiness of stems and tree hollows.

From insectivorous mammals, the hedgehog, preparing for hibernation, collects moss, leaves, hay in a secluded place and arranges a nest for itself. But it “settles” in its new home only when the temperature is kept below 10 ° C for a long time. Before that, the hedgehog eats plentifully in order to accumulate energy in the form of fat.

Hibernation brown bears is a slight numbness. In nature, in the summer, a bear accumulates a thick layer of subcutaneous fat and, immediately before the onset of winter, settles in its lair for hibernation. Usually the lair is covered with snow, so it is much warmer inside than outside. During hibernation, the accumulated fat reserves are used by the bear's body as a source of nutrients, and also protect the animal from freezing.

From a physiological point of view, the hibernation of mammals is characterized by the weakening of all vital functions of the body to the minimum that would allow them to survive adverse winter conditions without food.

By winter or dry summer, the body accumulates reserve energy substances that help to survive the difficult season, for example, glycogen. Animals get fat in one way or another. In some species, fat is up to 25% of the total body weight. For example, a small ground squirrel in the spring has a mass of about 100-150 g, and in the middle of summer - up to 400 g.

Adaptations to adverse environmental conditions are also expressed in migrations. So, in autumn, as the food conditions worsen, the bulk of arctic foxes and reindeer migrate from the tundra to the south, to the forest-tundra and even to the taiga, where it is easier to get food from under the snow. Following the deer, the tundra wolves also migrate south. In the northern regions of the tundra, hare hares at the beginning of winter undertake massive migrations to the south, in the spring - in the opposite direction. Mountain ungulates by the summer rise to the upper mountain belts with their rich herbage, in winter, as the depth of the snow cover increases, they descend. And in this case, migrations of some predators, such as wolves, are observed combined with ungulates.

In general, migrations are characterized by a relatively smaller number of species than birds and fish. They are most developed in marine animals, bats and ungulates, while among the species of the most numerous groups - rodents, insectivores and small predators - they are practically absent.

An alternative to migration in these animals is hibernation. Distinguish between facultative seasonal and continuous seasonal hibernation. In the first case, body temperature, the number of respiratory movements and the overall level of metabolic processes are reduced a little. Sleep is easily interrupted by a change of scenery or anxiety (bears, raccoons). This continuous seasonal hibernation is characterized by a loss of the ability to thermoregulate, a sharp reduction in the number of respiratory movements and contractions of the heart muscle, a fall general level metabolism (marmots, ground squirrels).

An important adaptation to experiencing adverse conditions is the gathering of food supplies. Among other vertebrates, only a few groups of birds (passerines, owls, woodpeckers) collect food for the winter, but the size of their reserves and the adaptive significance of this activity are negligible compared to mammals.

Burial of excess prey is common in. So, weasels and ermines collect 20-30 voles and mice each, black polecats pile several dozen frogs under the ice, minks - several kilograms of fish. Larger predators (martens, wolverines, cats, bears) hide the remains of prey in secluded places, under fallen trees, under stones. Leopards often hide part of their prey in the branches of trees. characteristic feature Predators store food because no special storerooms are built for its burial, only one individual that built it uses the stock. In general, stocks serve only as a small help for experiencing a low-feeding period, and they cannot prevent a sudden onset of starvation. Various rodents and pikas store their food in a different way, although in this case, there are also different degrees of perfection of storage and its significance. Flying squirrels collect several tens of grams of terminal branches and catkins of alder and birch, which they put into hollows. Squirrels are buried in fallen leaves, in hollows and in the ground acorns and nuts. They also hang mushrooms on tree branches. One squirrel in the dark coniferous taiga stocks up to 150-300 mushrooms, and in the ribbon forests of Western Siberia, where food conditions are worse than in the taiga, up to 1500-2000 mushrooms, they mainly oil. The reserves made by the squirrel are used by many individuals of this species.

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Adaptation- this is an adaptation of the body to environmental conditions due to a complex of morphological, physiological, and behavioral characteristics.

Different organisms adapt to different conditions environment, and as a result moisture-loving hydrophytes and "dry-bearers" - xerophytes(Fig. 6); saline soil plants halophytes; shade tolerant plants sciophytes), and requiring full sunlight for normal development ( heliophytes); animals that live in deserts, steppes, forests or swamps are nocturnal or diurnal. Groups of species with a similar attitude to environmental conditions (that is, living in the same ecotopes) are called environmental groups.

The ability to adapt to adverse conditions in plants and animals differ. Due to the fact that animals are mobile, their adaptations are more diverse than those of plants. Animals can:

- to avoid adverse conditions (birds from winter starvation and cold fly to warmer climes, deer and other ungulates wander in search of food, etc.);

- fall into suspended animation - a temporary state in which life processes are so slowed down that their visible manifestations are almost completely absent (stupor of insects, hibernation of vertebrates, etc.);

- adapt to life in adverse conditions (their coat and subcutaneous fat save them from frost, desert animals have devices for economical use of water and cooling, etc.). (Fig. 7).

Plants are inactive and lead an attached lifestyle. Therefore, only the last two variants of adaptations are possible for them. Thus, plants are characterized by a decrease in the intensity of vital processes during unfavorable periods: they shed their leaves, overwinter in the form of dormant organs buried in the soil - bulbs, rhizomes, tubers, and remain in the state of seeds and spores in the soil. In bryophytes, the whole plant has the ability to anabiosis, which, in a dry state, can persist for several years.

plant resistance to unfavorable factors increases due to special physiological mechanisms: changes in osmotic pressure in cells, regulation of evaporation intensity with the help of stomata, use of “filter” membranes for selective absorption of substances, etc.

Different organisms develop adaptations at different rates. They occur most rapidly in insects that can adapt to the action of a new insecticide in 10–20 generations, which explains the failure of chemical control of insect pest population density. The process of developing adaptations in plants or birds occurs slowly, over centuries.

The observed changes in the behavior of organisms are usually associated with hidden traits that they had, as it were, "in reserve", but under the influence of new factors, they appeared and increased the resistance of species. Such hidden signs explain the resistance of some types of trees to the action industrial pollution(poplar, larch, willow) and some weed species to the action of herbicides.

The composition of the same ecological group often includes organisms that are not similar to each other. This is due to the fact that different types of organisms can adapt differently to the same environmental factor.

For example, they experience cold differently warm-blooded(they are called endothermic, from the Greek words endon - inside and terme - heat) and cold-blooded (ectothermic, from the Greek ectos - outside) organisms. (Fig. 8.)

The body temperature of endothermic organisms does not depend on the ambient temperature and is always more or less constant, its fluctuations do not exceed 2–4 o even during the most severe frosts and the most intense heat. These animals (birds and mammals) maintain their body temperature by internal heat production based on intensive metabolism. They keep their body heat at the expense of warm “fur coats” made of feathers, wool, etc.

Physiological and morphological adaptations are complemented by adaptive behavior (selection of wind-protected places for lodging for the night, construction of burrows and nests, group overnight stays with rodents, close groups of penguins warming each other, etc.). If the ambient temperature is very high, then endothermic organisms are cooled by special adaptations, for example, by evaporation of moisture from the surface of the mucous membranes. oral cavity and upper respiratory tract. (For this reason, in the heat, the dog's breathing quickens and he sticks out his tongue.)

The body temperature and mobility of ectothermic animals depends on the ambient temperature. Insects and lizards become lethargic and inactive in cool weather. At the same time, many animal species have the ability to choose a place with favorable conditions for temperature, humidity and sunlight (lizards bask on illuminated rock slabs).

However, absolute ectothermy is observed only in very small organisms. Most cold-blooded organisms are still capable of poor regulation of body temperature. For example, in actively flying insects - butterflies, bumblebees, the body temperature is maintained at 36–40 ° C even at air temperatures below 10 ° C.

Similarly, species of the same ecological group in plants differ in their appearance. They can also adapt to the same environmental conditions different ways. So, different types of xerophytes save water in different ways: some have thick cell membranes, others have pubescence or a wax coating on the leaves. Some xerophytes (for example, from the labiaceae family) emit pairs essential oils, which wrap them like a "blanket", which reduces evaporation. root system in some xerophytes it is powerful, it goes into the soil to a depth of several meters and reaches the groundwater level (camel thorn), in others it is superficial, but highly branched, which allows collecting precipitation water.

Among the xerophytes there are shrubs with very small hard leaves that can be shed in the driest season (caragana shrub in the steppe, desert shrubs), turf grasses with narrow leaves (feather grass, fescue), succulents(from the Latin succulentus - juicy). Succulents have succulent leaves or stems that store water and easily tolerate high temperatures air. Succulents include American cacti and saxaul growing in the Central Asian deserts. They have a special type of photosynthesis: stomata open for a short time and only at night, during these cool hours, plants store carbon dioxide, and during the day they use it for photosynthesis with closed stomata. (Fig. 9.)

A variety of adaptations to survive unfavorable conditions on saline soils is also observed in halophytes. Among them there are plants that are able to accumulate salts in their bodies (soleros, swede, sarsazan), secrete excess salts on the surface of the leaves with special glands (kermek, tamariks), “keep” salts out of their tissues due to the “root barrier” impervious to salts "(wormwood). In the latter case, the plants have to be content with a small amount of water and they have the appearance of xerophytes.

For this reason, one should not be surprised that under the same conditions there are plants and animals that are different from each other, which have adapted to these conditions in different ways.

Control questions

1. What is adaptation?

2. Due to what animals and plants can adapt to adverse environmental conditions?

2. Give examples of ecological groups of plants and animals.

3. Tell us about the different adaptations of organisms to experiencing the same adverse environmental conditions.

4. What is the difference between adaptations to low temperatures in endothermic and ectothermic animals?

"How different animals eat" - Ways of feeding different animals. Herbivores are animals that need plant foods. Confusion game. Here is a shy deer at the edge, he is not too lazy to pluck the grass. What a terrible predator. All butterflies are characterized by the presence of a long movable proboscis. An exciting excursion. Crayfish. Types of teeth. Bee. We are in the meadow. Animals. Prudovik. How does a whale eat? These animals are helped to feed by teeth that bite off.

"Skin Diseases in Animals" - Endogenous factors. Ulcer. granulation barrier. Warty dermatitis. Furuncle in a dog. Clinical signs. Dermatitis of the interdigital region. Furuncles in a dog. Scar. Erythema. Seborrhea. Hydradenitis. Redness appears around the hair. The initial stage of eczema. local treatment. Significant swelling develops. Reflex eczema. Skin diseases. Eczema. Diagram of eczema formation. Bubble. folliculitis diagram.

"Trematodoses" - Helminths. pathological changes. Prevention. Trematode eggs. General form trematodes. pathogenesis and immunity. Biology of development. Pathogens. Sources of the spread of invasion. Pathogenesis. Ursovermit. Trematodoses. Paramphistomatosis. Fascioliasis. Bitionol. Common fasciola. Fallen animal. Giant fasciola. Life time diagnosis. Adolescaria. Polytrem. Niclosamide. Fasciola vulgaris. Biology of the development of paramphistomata.

"Types of protective colors" - Collective mimicry is effective. collective mimicry. transparent body. Mimicry Muller. Mimicry. Protective (cryptic) coloring. Consider animals. Eyes. Dissecting coloration. Warning coloration. Greatest effect. Threatening coloration. The relative nature of fitness. Mimesia. Types of protective colors of animals. Examples of eye camouflage. classical mimicry. Examples of warning coloration.

"Seasonal changes in animal life" - Colorado potato beetle. Migrations. Numbness. Textbook questions. Hibernation and torpor. Reindeer migrations. Signals. Butterfly. Bat. Cluster bats. Seasonal changes in animal life. Hibernation. Flights of birds. environment conditions.

Causes of imaginary death (anabiosis) in plant and animal organisms

allowing them to survive adverse winter conditions.

O.K. Smirnova, teacher of biology of the highest category of Lyceum No. 103, Rostov-on-Don.

Goals: increase the areas of knowledge of students; learn to analyze the phenomenon of temporary cessation of vital activity in living organisms, using it as a means to adapt and survive in adverse conditions.

Equipment: tables of mollusks, crustaceans, insects, fish, amphibians, reptiles, birds, mammals.

The winter season is unfavorable for many representatives of the animal and plant world, both due to low temperatures and a sharp decrease in the ability to get food. In the course of evolutionary development, many species of animals and plants have acquired peculiar adaptive mechanisms in order to survive in an unfavorable season. In some species of animals, the instinct to create food reserves has arisen and established itself; others have developed another adaptation - migration. Strikingly long flights of many species of birds, migration of some species of fish and other representatives of the animal world are known. However, in the process of evolution in many species of animals, another perfect physiological mechanism of adaptation was noticed - the ability to fall into a lifeless state at first glance, which manifests itself differently in different species of animals and has different names (anabiosis, hypothermia, etc.). Meanwhile, all these conditions are characterized by inhibition of the body's vital functions to the minimum that allows it to survive adverse winter conditions without eating. Such a state of imaginary death falls into those species of animals that are not able to provide themselves with food in winter and for them there is a danger of death from cold and hunger. And all this, developed in the process of evolution, is subject to strict natural expediency - the need to preserve the species.

Hibernation is a widespread phenomenon in nature, despite the fact that its manifestations are different in representatives of certain groups of animals, whether they are animals with unstable body temperature (poikilothermic), also called cold-blooded, in which the body temperature depends on the ambient temperature, or animals with a constant body temperature (homeothermic), also called warm-blooded.

From among animals with unstable body temperature, various types of mollusks, crustaceans, arachnids, insects, fish, amphibians and reptiles fall into a state of hibernation, and from animals with a constant body temperature, several species of birds and many species of mammals.

How do snails hibernate?

From the soft-bodied type, many types of snails fall into hibernation (for example, all land snails). Encountered garden snails hibernate in October, and it lasts until early April. After a long preparatory period, during which they accumulate the necessary nutrients in their bodies, the snails find or dig minks so that several individuals can winter together deep underground, where the temperature will be maintained at 7 - 8 ° C. Having clogged the minks well, the snails descend to the bottom and lie with the shell opening up. They then close this hole, releasing a slimy substance that soon hardens and becomes elastic (film-like). With a significant cold snap and a lack of nutrients in the body, the snails burrow even deeper into the ground and form another film, thus creating air chambers that play the role of an excellent insulator. It has been established that during a long wintering period, snails lose more than 20% of their weight, with the largest loss occurring in the first 25-30 days. This is due to the fact that all metabolic processes gradually fade in order to reach the minimum at which the animal falls almost into a state of suspended animation with barely perceptible vital functions. During hibernation, the snail does not feed, breathing almost stops. In the spring, when the first warm days come and the soil temperature reaches 8-10°C, when the vegetation begins to develop and the first rains fall, the snails come out of their winter shelters. Then begins intensive activity to restore depleted food reserves in their body; this is expressed in the absorption of a huge amount of food compared to their body.

Water snails, pond snails, also fall into a state of hibernation - most of them burrow into the silt at the bottom of the reservoir in which they live.

Where do crayfish hibernate?

Everyone knows the popular threat among the people: "I'll show you where the crayfish hibernate!". It is believed that this proverb appeared during the time of serfdom, when the landowners, punishing the guilty serfs, forced them to catch crayfish in the winter. Meanwhile, it is known that this is almost impossible, since crayfish overwinter, deeply buried in holes at the bottom of reservoirs.

From the point of view of taxonomy, the class of crustaceans is divided into two subclasses - higher and lower crustaceans.

Of the higher crustaceans, river, marsh and lake crayfish fall into a state of hibernation. Males hibernate in groups in deep pits at the bottom, and females alone in minks, and in November they glue fertilized eggs to their short legs, from which ant-sized crustaceans hatch only in June.

Of the lower crustaceans, water fleas (genus Daphnia) are of interest. They lay, depending on the conditions, two types of eggs - summer and winter. Winter eggs have a strong shell and are formed when unfavorable living conditions occur. For some species of lower crustaceans, drying out and even freezing of eggs is a necessary condition for the continuation of their development.

Diapause in insects.

By the number of species, insects surpass all other classes. Their body temperature depends on the environment, which has a strong effect on the speed of vital influences, and low temperatures greatly reduce this speed. At negative temperatures, the entire development of the insect slows down or practically stops. This anabiotic state, known as "diapause", is a reversible cessation of developmental processes and is caused by external factors. Diapause occurs when conditions are unfavorable for life and continues throughout the winter, until conditions become more favorable with the onset of spring.

The onset of the winter season finds different types of insects at different stages of their development, in which they winter - in the form of eggs, larvae, pupae or adult forms, but usually each individual species falls into diapause at a certain stage of its development. So, for example, the seven-spotted ladybug hibernates as an adult.

It is characteristic that the wintering of insects is preceded by a certain physiological preparation of their body, consisting of the accumulation of free glycerol in their tissues, which does not allow freezing. This occurs at the stage of development of the insect in which they will overwinter.

Even with the onset of the first signs of a cold snap in autumn, insects find comfortable shelters (under stones, under the bark of trees, under fallen leaves in burrows in the soil, etc.), where, after a snowfall, the temperature is moderately low and uniform.

The duration of diapause in insects is directly related to the reserves of fat in the body. Bees do not fall into a long diapause, but still at a temperature of 0 to 6 ° C they become numb and can stay in this state for 7-8 days. At lower temperatures they die.

It is also interesting how insects accurately determine the moment when they should exit the anabiotic state. Scientist N.I. Kalabukhov studied anabiosis in some species of butterflies. He found that the duration of diapause varies from species to species. For example, the peacock butterfly was in a state of suspended animation for 166 days at a temperature of 5.9 ° C, while the silkworm needed 193 days at a temperature of 8.6 ° C. According to the scientist, even differences in the geographical area affect the duration of diapause.

Do fish hibernate?

In a peculiar way, some species of a large class of fish adapt to low water temperatures in winter. Normal body temperature in fish is not constant and corresponds to the temperature of the water. With a sudden sharp drop in water temperature, the fish fall into a state of shock. It is enough, however, for the water to warm up, and they quickly “come to life”. Experiments have shown that frozen fish come to life only when their blood vessels are not frozen.

Originally adapted to low water temperatures in winter, some fish that live in Arctic waters: they change their blood composition. With a decrease in water temperature in autumn, salts accumulate in their blood in such a concentration that is characteristic of sea water, and at the same time the blood freezes with great difficulty (a kind of antifreeze).

From freshwater fish, carp, ruff, perch, catfish and others fall into hibernation in November. When the water temperature drops below 8 - 10°C, these fish move to the deeper parts of the reservoirs, burrow into the silt in large groups and remain there in a state of hibernation throughout the winter.

Some marine fish also endure extreme cold while hibernating. So, for example, herring already in autumn approach the coast of the Arctic Ocean in order to fall into a state of hibernation at the bottom of some small bay. The Black Sea anchovy also winters in the southern regions of the sea - off the coast of Georgia, at this time it is not active and does not consume food. And the Azov anchovy before the offensive winter period migrates to the Black Sea, where it gathers in groups in a relatively sedentary state.

Hibernation in fish is characterized by their extremely limited activity, complete cessation of feeding, and a sharp decrease in metabolism. At this time, their body is supported by the reserves of nutrients accumulated due to abundant nutrition in the autumn.

hibernation of amphibians

In terms of lifestyle and structure, the class of amphibians is transitional between typically aquatic vertebrates and typically terrestrial animals. It is known that various types of frogs, newts, salamanders also spend the unfavorable winter season in a state of stupor, as these are animals with unstable body temperature, which depends on the ambient temperature.

It has been established that the hibernation of frogs lasts from 130 to 230 days and its duration depends on the duration of winter.

In reservoirs, in order to overwinter, frogs gather in groups of 10-20 specimens, burrow into silt, into underwater depressions and other voids. During hibernation, frogs breathe only through their skin.

In winter, newts usually nestle under warm, rotten stumps and trunks of fallen trees. If they do not find such convenient "apartments" nearby, they are satisfied with cracks in the soil.

Reptiles hibernate too

From the class of reptiles, almost all species of our fauna fall into a state of hibernation in winter. Low winter temperatures are the main reason for this phenomenon.

Winter quarters are usually underground caverns or voids formed around large old stumps with rotten roots, crevices in rocks, and other places that are not accessible to their enemies. In such shelters, a large number of snakes gather, forming huge coils of snakes. It has been established that the temperature of snakes during hibernation almost does not differ from the ambient temperature.

Most species of lizards (meadow, striped, green, forest, spindle) also hibernate, burrowing into the soil, into burrows that are not threatened by flooding. On warm sunny days in winter, the lizards may "awake" and crawl out of their winter shelters for several hours to hunt, after which they again hide in their burrows, falling into a state of torpor.

Bog turtles spend the winter burrowing into the silt of the reservoirs in which they live, while terrestrial turtles climb to a depth of 0.5 m into the soil into some natural shelters or holes of moles, foxes, rodents, covering themselves with peat, moss and wet leaves.

Preparation for wintering begins in October, when turtles accumulate fat. In the spring, with temporary warming, they wake up, sometimes for a whole week.

Are there birds that hibernate in winter?

Most animals with unstable body temperature, which depends on the environment, fall into a state of hibernation. But surprisingly, many animals with a constant body temperature, such as birds, can also hibernate during the unfavorable seasons of the year. It is known that most birds avoid adverse winter conditions by migrating. Even Aristotle, in his multi-volume History of Animals, drew attention to the fact that “some birds fly away to spend the winter in warm countries, while others take refuge in various shelters where they hibernate.”

The great Swedish naturalist Karl Linnaeus also came to this conclusion, who in his work “The System of Nature” wrote: “In autumn, when the cold starts, swallows, not finding enough insects for food, begin to seek shelter for wintering in reed beds along the banks of lakes and rivers. ".

The torpor into which some species of birds fall is very different from the hibernation common to many mammals. First of all, the body of birds not only does not accumulate energy reserves in the form of fat, but, on the contrary, consumes a significant part of them. While mammals go into hibernation, having noticeably gained weight, birds lose a lot of weight before stupor. That is why the phenomenon of torpor in birds, according to the Soviet biologist R. Potapov, should be called not hibernation, but hypothermia.

Until now, the mechanism of hypothermia in birds is not fully understood. The fall of birds into a state of stupor under adverse living conditions is an adaptive physiological reaction that has been fixed in the process of evolution.

What mammals hibernate in winter?

As in the animals discussed earlier, so in mammals, hibernation is a biological adaptation to survive the unfavorable season of the year. Although animals with a constant body temperature usually tolerate cold climates, the lack of suitable food in winter has caused some of them to acquire and gradually consolidate in the course of evolution this peculiar instinct - to spend an unfavorable winter season in an inactive state of hibernation.

There are three types of hibernation according to the degree of torpor:

1) slight torpor, which easily stops (raccoons, badgers, bears, raccoon dogs);

2) complete stupor, accompanied by periodic awakenings only on warmer winter days (hamsters, chipmunks, bats);

3) real incessant hibernation, which is a stable, prolonged stupor (ground squirrels, hedgehogs, marmots, jerboas).

Winter hibernation of mammals is preceded by a certain physiological preparation of the organism. It consists primarily in the accumulation of fat reserves, mainly under the skin. In some winter sleepers, subcutaneous fat reaches 25% of the total body weight. For example, ground squirrels get fat at the beginning of autumn, increasing their body weight three times compared to spring-summer weight. Before hibernation, hedgehogs and brown bears, as well as all bats, get significantly fatter.

Other mammals, such as hamsters and chipmunks, do not accumulate large stores of fat, but store food in their shelter to use during their brief periods of awakening in winter.

During hibernation, all species of mammals lie motionless in their burrows, curled up into a ball. So it is best to keep warm and limit heat exchange with the environment. Zimnik apartments of many mammals are natural emptiness of stems and tree hollows.

From insectivorous mammals, the hedgehog, preparing for hibernation, collects moss, leaves, hay in a secluded place and arranges a nest for itself. But it “settles” in its new home only when the temperature is kept below 10 ° C for a long time. Before that, the hedgehog eats abundantly in order to store energy in the form of fat.

Winter hibernation of brown bears is a slight stupor. In nature, in the summer, a bear accumulates a thick layer of subcutaneous fat and, immediately before the onset of winter, settles in its lair for hibernation. Usually the lair is covered with snow, so it is much warmer inside than outside. During hibernation, the accumulated fat reserves are used by the bear's body as a source of nutrients, and also protect the animal from freezing.

From a physiological point of view, the hibernation of mammals is characterized by the weakening of all vital functions of the body to the minimum that would allow them to survive adverse winter conditions without food.