Animals and plants are forced to adapt to many factors, and these adaptations are developed over a certain period of time, often in the process of evolution and natural selection, being fixed at the genetic level.

Adaptation(from lat. adapto - I adapt) - adaptations of the structure and functions of organisms to environmental conditions in the process of evolution.

When analyzing the organization of any animal and plant, a striking correspondence of the form and functions of the organism to environmental conditions is always found. Yes, among marine mammals dolphins have the most advanced adaptations for rapid movement in aquatic environment: torpedo-shaped shape, a special structure of the skin and subcutaneous tissue, which increases the streamlining of the body, and consequently, the speed of sliding in the water.

There are three main forms of manifestation of adaptations: anatomical-morphological, physiological and behavioral.

Anatomical and morphological adaptations are some kind of external and internal features in the structure of certain organs of plants and animals, allowing them to live in a certain environment with a certain combination of environmental factors. In animals, they are often associated with lifestyle, the nature of nutrition. Examples:

· hard shell turtles, providing protection from predatory animals

Woodpecker - chisel-shaped beak, hard tail, characteristic arrangement of fingers.

Physiological adaptations consist in the ability of organisms to change some of their physiological processes during critical periods in their life

· The smell of the flower can serve to attract insects and thereby promote pollination of the plant.

· Deep dormancy in many plants growing in the middle latitudes of the northern hemisphere, falling into a stupor or hibernation in some animals with the onset of a cold period).

· Biological antifreezes that increase the viscosity of internal media and prevent the formation of ice crystals that would destroy cells (up to 10% in ants, up to 30% in wasps).

In the dark, the sensitivity of the eye to light increases many thousands of times within an hour, which is associated both with the restoration of sight, pigments, and with changes in nerve elements and nerve cells cerebral cortex.

An example of physiological adaptations are also the features of the enzymatic set in digestive tract animals, determined by the set and composition of food. Thus, desert dwellers are able to provide their need for moisture by biochemical oxidation of fats.

Behavioral(ethological) adaptations are forms of adaptive behavior of animals. Examples:

· To ensure normal heat exchange with the environment: the creation of shelters, daily and seasonal migration of animals in order to select the optimal temperature conditions.



Hummingbird Oreotrochis estella, living in the high Andes, builds nests on the rocks, and on the side facing the East. During the night, the stones give off the heat accumulated during the day, thereby providing a comfortable temperature until the morning.

In areas with harsh climates, but snowy winters the temperature under the snow can be 15-18ºС higher than outside. It is estimated that the white partridge, spending the night in a snowy hole, saves up to 45% of energy.

Many animals use group roosting: pikas of the genus Certhia(birds) gather in cold weather groups up to 20 individuals. A similar phenomenon has been described in rodents.

· Adaptive behavior can appear in predators in the process of tracking and chasing prey.

Most adaptations is a combination of the above types. For example, bloodsucking in mosquitoes is provided by a complex combination of adaptations such as the development of specialized parts oral apparatus adapted to sucking, the formation of search behavior to find the prey animal, as well as the development salivary glands special secrets that prevent clotting of sucked blood.

One of the fundamental properties of living nature is the cyclicity of most of the processes occurring in it, which ensures the adaptation of plants and animals during their development with the main periodic factors. Let us dwell on such a phenomenon in wildlife as photoperiodism.

Photoperiodism - response of organisms to seasonal changes in day length. Opened by V. Garner and N. Allard in 1920 during selection work with tobacco.

Light has a leading influence on the manifestation of daily and seasonal activity of organisms. This is an important factor, since it is the change in illumination that causes the alternation of a period of rest and intensive life activity, many biological phenomena in plants and animals (that is, it affects the biorhythm of organisms).

For example, 43% of the sun's rays reach the Earth's surface. Plants are able to capture from 0.1 to 1.3%. They absorb the yellow-green spectrum.

And a signal of the approach of winter for plants and animals is a decrease in the length of the day. Plants undergo a gradual physiological restructuring, the accumulation of a supply of energy substances before winter dormancy. By photoperiodic reaction plant organisms are divided into two groups:

Short-day organisms - flowering and fruiting occurs at 8-12 hours of light (buckwheat, millet, hemp, sunflower).

· Organisms long day. For flowering and fruiting in long-day plants, it is necessary to lengthen the day to 16-20 hours (plants of temperate latitudes), for which a decrease in day length to 10-12 hours is a signal of the approach of an unfavorable autumn-winter period. These are potatoes, wheat, spinach.

· Neutral to length for the plant. Flowering occurs at any length of the day. These are dandelion, mustard and tomato.

The same is found in animals. During the day, the activity of each organism falls on certain hours. The mechanisms that allow organisms to change their state cyclically are called "biological clocks".

Bibliographic list for the section

1. Galperin, M.V. General ecology: [proc. for avg. prof. education] / M.V. Galperin. - M. : Forum: Infra-M, 2006. - 336 p.

2. Korobkin, V.I. Ecology [Text] / V.I. Korobkin, L.V. Peredelsky. - Rostov-on-Don: Phoenix, 2005. - 575 p.

3. Mirkin, B.M. Fundamentals of general ecology [Text]: textbook. allowance for university students studying natural sciences. specialties / B.M. Mirkin, L.G. Naumov; [ed. G.S. Rosenberg]. - M. : Univ. book, 2005. - 239 p.

4. Stepanovskikh, A.S. General ecology: [proc. for universities on ecol. specialties] / A.S. Stepanovsky. - 2nd ed., add. and reworked. - M. : UNITI, 2005. - 687 p.

5. Furyaev, V.V. General ecology and biology: textbook. allowance for students of the specialty 320800 pts. forms of education / V.V. Furyaev, A.V. Furyaev; Feder. education agency, Sib. state technol. un-t, Institute of Forests named after. V. N. Sukacheva. - Krasnoyarsk: SibGTU, 2006. - 100 p.

6. Golubev, A.V. General ecology and environmental protection: [proc. manual for all specialties] / A.V. Golubev, N.G. Nikolaevskaya, T.V. Sharapa; [ed. ed.] ; State. educate. institution of higher prof. Education "Moscow. state. un-t forest". - M. : MGUL, 2005. - 162 p.

7. Korobkin, V.I. Ecology in questions and answers [Text]: textbook. allowance for university students / V.I. Korobkin, L.V. Peredelsky. - 2nd ed., revised. and additional - Rostov n / a: Phoenix, 2005. - 379 p. : schemes. - Bibliography: p. 366-368. - 103.72 rubles

Control questions to section 3

1. The concept of habitat, its types.

2. What are environmental factors, how are they classified?

3. The concept of a limiting factor, examples.

4. The law of optimum-pessimum (figure). Examples.

5. Law of interaction of environmental factors. Examples.

6. The law of tolerance (Shelford). Examples.

7. Environmental rules: D. Allen, K. Bergman, K. Gloger.

8. Adaptations of living organisms, their ways and forms. Examples.

9. Photoperiodism, biological rhythms: concept, examples.


SECTION 4: POPULATION ECOLOGY

The grandiose inventions of the human mind never cease to amaze, there is no limit to fantasy. But what nature has been creating for many centuries surpasses the most creative ideas and designs. Nature has created more than one and a half million species of living individuals, each of which is individual and unique in its forms, physiology, adaptability to life. Examples of adaptation of organisms to the ever-changing conditions of life on the planet are examples of the wisdom of the creator and a constant source of problems for biologists to solve.

Adaptation means adaptability or habituation. This is a process of gradual rebirth of the physiological, morphological or psychological functions of a creature in a changed environment. Both individual individuals and entire populations undergo changes.

A striking example of direct and indirect adaptation is the survival of flora and fauna in the zone of increased radiation around Chernobyl nuclear power plant. Direct adaptability is characteristic of those individuals who managed to survive, get used to it and begin to reproduce, some did not stand the test and died (indirect adaptation).

Since the conditions of existence on Earth are constantly changing, the processes of evolution and fitness in living nature are also a continuous process.

A recent example of adaptation is changing the habitat of a colony of green Mexican arating parrots. Recently, they have changed their habitual habitat and settled in the very mouth of the Masaya volcano, in an environment constantly saturated with high concentration sulfuric gas. Scientists have not yet given an explanation for this phenomenon.

Types of adaptation

A change in the whole form of an organism's existence is a functional adaptation. An example of adaptation, when changing conditions lead to mutual adaptation of living organisms to each other, is a correlative adaptation or co-adaptation.

Adaptation can be passive, when the functions or structure of the subject occur without his participation, or active, when he consciously changes his habits to match the environment (examples of people adapting to natural conditions or society). There are cases when the subject adapts the environment to his needs - this is an objective adaptation.

Biologists divide the types of adaptation according to three criteria:

  • Morphological.
  • Physiological.
  • behavioral or psychological.

Examples of adaptation of animals or plants in their pure form are rare, most cases of adaptation to new conditions occur in mixed forms.

Morphological adaptations: examples

Morphological changes are changes in the shape of the body, individual organs or the entire structure of a living organism that have occurred in the process of evolution.

The following are morphological adaptations, examples from the animal and plant world, which we take for granted:

  • The transformation of leaves into spines in cacti and other plants of arid regions.
  • Turtle shell.
  • Streamlined body shapes of inhabitants of reservoirs.

Physiological adaptations: examples

Physiological adaptation is a change in a number of chemical processes occurring inside the body.

  • The release of a strong scent by flowers to attract insects contributes to dusting.
  • The state of anabiosis, which the simplest organisms are able to enter, allows them to maintain their vital activity after many years. The oldest bacterium capable of reproduction is 250 years old.
  • The accumulation of subcutaneous fat, which is converted into water, in camels.

Behavioral (psychological) adaptations

Examples of human adaptation are more associated with the psychological factor. Behavioral characteristics characteristic of flora and fauna. So, in the process of evolution, change temperature regime causes some animals to hibernate, birds to fly south to return in spring, trees to shed their leaves and slow down the flow of juices. The instinct to choose the most suitable partner for procreation drives the behavior of animals during the mating season. Some northern frogs and turtles freeze completely for the winter and thaw, reviving with the onset of heat.

Factors causing the need for change

Any adaptation processes are a response to environmental factors that lead to a change in the environment. Such factors are divided into biotic, abiotic and anthropogenic.

Biotic factors are the influence of living organisms on each other, when, for example, one species disappears, which serves as food for another.

Abiotic factors are changes in the environment inanimate nature when the climate changes, soil composition, water supply, cycles of solar activity. Physiological adaptations, examples of influence abiotic factors- equatorial fish that can breathe both in water and on land. They are well adapted to the conditions when the drying up of rivers is a frequent occurrence.

Anthropogenic factors - influence human activity that changes the environment.

Habitat adaptations

  • illumination. In plants, this individual groups, which differ in the need for sunlight. Light-loving heliophytes live well in open spaces. In contrast, they are sciophytes: plants of forest thickets feel good in shaded places. Among the animals there are also individuals whose active image life at night or underground.
  • Air temperature. On average, for all living things, including humans, the optimal temperature environment is considered to be the range from 0 to 50 ° C. However, life exists in almost all climatic regions of the Earth.

Opposite examples of adaptation to abnormal temperatures are described below.

Arctic fish do not freeze due to the production of a unique anti-freeze protein in the blood, which prevents the blood from freezing.

The simplest microorganisms are found in hydrothermal springs, the water temperature in which exceeds the boiling point.

Hydrophyte plants, that is, those that live in or near water, die even with a slight loss of moisture. Xerophytes, on the contrary, are adapted to live in arid regions, and die in high humidity. Among animals, nature has also worked on adapting to aquatic and non-aquatic environments.

Human adaptation

Man's ability to adapt is truly enormous. The secrets of human thinking are far from being fully revealed, and the secrets of the adaptive ability of people will remain for a long time to come. mysterious theme for scientists. The superiority of Homo sapiens over other living beings is in the ability to consciously change their behavior to the requirements of the environment or, conversely, the world according to your needs.

The flexibility of human behavior is manifested daily. If you give the task: "give examples of people's adaptation", the majority begins to recall exceptional cases of survival in these rare cases, and in new circumstances it is typical for a person every day. We try on a new environment at the moment of birth into the world, in kindergarten, school, in a team, when moving to another country. It is this state of accepting new sensations by the body that is called stress. Stress is a psychological factor, but nevertheless, many physiological functions change under its influence. In the case when a person accepts a new environment as positive for himself, the new state becomes habitual, otherwise stress threatens to become protracted and lead to a number of serious diseases.

Human adaptation mechanisms

There are three types of human adaptation:

  • Physiological. Most simple examples- acclimatization and adaptability to change of time zones or daily mode of operation. In the course of evolution, Various types people, depending on where they live. Arctic, alpine, continental, desert, equatorial types differ significantly in physiological parameters.
  • Psychological adaptation. This is the ability of a person to find moments of understanding with people of different psychotypes, in a country with a different level of mentality. It is common for a reasonable person to change his established stereotypes under the influence of new information, special occasions, stress.
  • Social adaptation. A type of addiction that is unique to humans.

All adaptive types are closely related to each other, as a rule, any change in habitual existence causes a need in a person for social and psychological adaptation. Under their influence, the mechanisms of physiological changes come into action, which also adapt to new conditions.

Such a mobilization of all body reactions is called an adaptation syndrome. New body reactions appear in response to drastic changes environment. At the first stage - anxiety - there is a change in physiological functions, changes in the work of metabolism and systems. Further, protective functions and organs (including the brain) are connected, they begin to turn on their protective functions and hidden capabilities. The third stage of adaptation depends on individual characteristics: a person either joins a new life and enters the usual course (in medicine, recovery occurs during this period), or the body does not accept stress, and the consequences are already taking a negative form.

Phenomena of the human body

In man, nature has a huge margin of safety, which is used in Everyday life only to a small extent. It manifests itself in extreme situations and is perceived as a miracle. In fact, the miracle is inherent in ourselves. An example of adaptation: the ability of people to adapt to a normal life after the removal of a significant part of the internal organs.

Natural innate immunity throughout life can be strengthened by a number of factors or, conversely, weakened by an incorrect lifestyle. Unfortunately, passion bad habits This is also the difference between humans and other living organisms.

The textbook complies with the Federal State Educational Standard for Secondary (Complete) General Education, is recommended by the Ministry of Education and Science of the Russian Federation and is included in the Federal List of Textbooks.

The textbook is addressed to students in grade 11 and is designed to teach the subject 1 or 2 hours per week.

Modern design, multi-level questions and tasks, Additional Information and the possibility of parallel work with an electronic application contribute to the effective assimilation of educational material.


Rice. 33. Winter coloring of a hare

So, as a result of the action of the driving forces of evolution, organisms develop and improve adaptations to environmental conditions. Anchoring in isolated populations various adaptations may eventually lead to the formation of new species.

Review questions and assignments

1. Give examples of the adaptability of organisms to the conditions of existence.

2. Why do some animals have a bright, unmasking color, while others, on the contrary, are patronizing?

3. What is the essence of mimicry?

4. Does the action of natural selection extend to the behavior of animals? Give examples.

5. What are the biological mechanisms for the emergence of adaptive (concealing and warning) coloration in animals?

6. Are physiological adaptations factors that determine the level of adaptability of the organism as a whole?

7. What is the essence of the relativity of any adaptation to living conditions? Give examples.

Think! Execute!

1. Why is there no absolute adaptation to living conditions? Give examples proving the relative nature of any device.

2. Boar cubs have a characteristic striped coloration that disappears with age. Give similar examples of color changes in adults compared to offspring. Can this pattern be considered common to the entire animal kingdom? If not, for which animals and why is it typical?

3. Gather information about warning color animals in your area. Explain why knowledge of this material is important for everyone. Make an information stand about these animals. Give a presentation on this topic in front of elementary school students.

Work with computer

Refer to the electronic application. Study the material and complete the assignments.

Repeat and remember!

Human

Behavioral adaptations are innate unconditioned reflex behavior. Innate abilities exist in all animals, including humans. A newborn baby can suck, swallow and digest food, blink and sneeze, react to light, sound and pain. These are examples unconditioned reflexes. Such forms of behavior arose in the process of evolution as a result of adaptation to certain, relatively constant conditions environment. Unconditioned reflexes are inherited, so all animals are born with a ready-made complex of such reflexes.

Each unconditioned reflex occurs to a strictly defined stimulus (reinforcement): some to food, others to pain, others to the appearance of new information, etc. The reflex arcs of unconditioned reflexes are constant and pass through the spinal cord or brain stem.

One of the most complete classifications unconditioned reflexes is a classification proposed by Academician P. V. Simonov. The scientist proposed to separate everything unconditioned reflexes into three groups, differing in the characteristics of the interaction of individuals with each other and with the environment. Vital reflexes(from lat. vita - life) are aimed at preserving the life of the individual. Failure to comply with them leads to the death of the individual, and the implementation does not require the participation of another individual of the same species. This group includes food and drink reflexes, homeostatic reflexes (maintaining a constant body temperature, optimal breathing rate, heart rate, etc.), defensive ones, which, in turn, are divided into passive-defensive (runaway, hiding) and active defensive (attack on a threatening object) and some others.

TO zoosocial, or role-playing reflexes include those variants of innate behavior that arise when interacting with other individuals of their species. These are sexual, parent-child, territorial, hierarchical reflexes.

The third group is reflexes of self-development. They are not connected with adaptation to a specific situation, but, as it were, turned to the future. Among them are exploratory, imitative and playful behavior.

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Adaptations (devices)

Biology and genetics

The relative nature of adaptation: according to a specific habitat, adaptations lose their significance when it changes; hare hare during a delay in winter or during a thaw in early spring noticeable against the background of arable land and trees; aquatic plants die when water bodies dry up, etc. Examples of adaptation Type of adaptation Characteristics of adaptation Examples Special shape and structure of the body Streamlined body shape gills fins Pinniped fish Protective coloration Sometimes continuous and dissecting; is formed in organisms living openly and makes them invisible ...

Adaptations (devices)

Adaptation (or adaptation) is a complex of morphological, physiological, behavioral and other features of an individual, population or species that ensures success in competition with other individuals, populations or species and resistance to environmental factors.

■ Adaptation is the result of the factors of evolution.

The relative nature of adaptation: corresponding to a specific habitat, adaptations lose their significance when it changes (the white hare during a delay in winter or during a thaw, in early spring it is noticeable against the background of arable land and trees; aquatic plants die when water bodies dry up, etc.).

Adaptation examples

Type of adaptation

Adaptation characteristic

Examples

The special shape and structure of the body

Streamlined body shape, gills, fins

Fish, pinnipeds

Protective coloration

It happens continuous and dismembering; is formed in organisms living openly, and makes them invisible against the background of the environment

Gray and white partridges; seasonal change in the color of the fur of a hare

Warning coloration

Bright, noticeable against the background of the environment; develops in species with protective means

Poisonous amphibians, stinging and poisonous insects, inedible and burning plants

Mimicry

Less protected organisms of one species are similar in color to protected poisonous ones of another species.

Some non-venomous snakes similar in color to poisonous

Disguise

The shape and color of the body makes the body look like objects of the environment.

Butterfly caterpillars are similar in color and shape to the knots of the trees where they live.

Functional fixtures

Warm-blooded, active metabolism

Allow to live in different climatic conditions

Passive Defense

Structures and features that determine the greater likelihood of life saving

Turtle shells, mollusk shells, hedgehog quills, etc.

instincts

Swarming in bees when a second queen appears, caring for offspring, searching for food

habits

Behavior changes in moments of danger

The cobra puffs out its hood, the scorpion lifts its tail

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Such an observation is interesting. In animals of the northern populations, all elongated parts of the body - limbs, tail, ears - are covered with a dense layer of wool and look relatively shorter than in representatives of the same species, but living in a hot climate.

This pattern, known as the Alain rule, applies to both wild and domestic animals.

There is a noticeable difference in the body structure of the northern fox and the fennec fox in the south, the northern wild boar and the wild boar in the Caucasus. Mongrel domestic dogs in Krasnodar Territory, large cattle local selection are distinguished by a lower live weight compared to representatives of these species, say, Arkhangelsk.

Often animals from the southern populations of long-legged and long-eared. Large ears, unacceptable at low temperatures, arose as an adaptation to life in a hot zone.

And the animals of the tropics have just huge ears (elephants, rabbits, ungulates). The ears of the African elephant are indicative, the area of ​​\u200b\u200bwhich is 1/6 of the surface of the entire body of the animal. They have abundant innervation and vascularity. IN hot weather in an elephant, approximately 1/3 of the entire circulating blood passes through the circulatory system of the ear shells. As a result of increased blood flow in external environment excess heat is given off.

The desert hare Lapus alleni is even more impressive with its adaptive abilities to high temperatures. In this rodent, 25% of the entire body surface falls on bare auricles. It is not clear what the main biological task of such ears is: to detect the approach of danger in time or to participate in thermoregulation. Both the first and the second task are solved by the animal very effectively. The rodent has a keen ear. The developed circulatory system of the auricles with a unique vasomotor ability serves only thermoregulation. By increasing and limiting blood flow through the auricles, the animal changes heat transfer by 200-300%. Its hearing organs perform the function of maintaining thermal homeostasis and saving water.

Due to the saturation of the auricles with thermosensitive nerve endings and rapid vasomotor reactions from the surface of the auricles, a large number of excess thermal energy in the elephant, and especially in the lepus.

The structure of the body of a relative of modern elephants, the mammoth, fits well into the context of the problem under discussion. This northern analogue of the elephant, judging by the preserved remains found in the tundra, was much larger than its southern relative. But the ears of the mammoth had a smaller relative area and, moreover, were covered with thick hair. The mammoth had relatively short limbs and a short trunk.

Long limbs are unfavorable at low temperatures, since too much thermal energy is lost from their surface. But in hot climates, long limbs are a useful adaptation. In desert conditions, camels, goats, horses of local selection, as well as sheep, cats, as a rule, have long legs.

According to H. Hensen, as a result of adaptation to low temperatures in animals, the properties of subcutaneous fat and bone marrow change. In arctic animals, bone fat from the phalanx of the fingers has a low melting point and does not freeze even in severe frosts. However, bone fat from bones that do not come into contact with a cold surface, such as the femur, has the usual physicochemical characteristics. Liquid fat in the bones of the lower extremities provides thermal insulation and joint mobility.

The accumulation of fat is noted not only in northern animals, for which it serves as a thermal insulation and a source of energy during a period when food is not available due to severe bad weather. Fat accumulate and animals living in hot climates. But the quality, quantity and distribution of body fat in northern and southern animals is different. In wild arctic animals, fat is distributed evenly throughout the body in the subcutaneous tissue. In this case, the animal forms a kind of heat-insulating capsule.

Animals temperate zone fat as a heat insulator accumulates only in species with a poorly developed coat. In most cases, stored fat serves as a source of energy during the hungry winter (or summer) period.

In hot climates, subcutaneous fat deposits carry a different physiological burden. The distribution of body fat throughout the body of animals is characterized by great unevenness. Fat is localized in the upper and back parts of the body. For example, in ungulates African savannas the fatty subcutaneous layer is localized along the spine. It protects the animal from the scorching sun. The belly is completely free of fat. It also makes a lot of sense. Ground, grass or water, which is colder than air, ensures efficient heat removal through the abdominal wall in the absence of fat. Small fat deposits and in animals in a hot climate are a source of energy for a period of drought and the associated hungry existence of herbivores.

The internal fat of animals in a hot and arid climate performs another extremely useful function. In conditions of lack or total absence water internal fat serves as a source of water. Special studies show that the oxidation of 1000 g of fat is accompanied by the formation of 1100 g of water.

An example of unpretentiousness in the arid conditions of the desert are camels, fat-tailed and fat-tailed sheep, and zebu-like cattle. The mass of fat accumulated in the humps of a camel and the fat tail of a sheep is 20% of their live weight. Calculations show that a 50-kilogram fat-tailed sheep has a water supply of about 10 liters, and a camel even more - about 100 liters. The last examples illustrate the morphophysiological and biochemical adaptations of animals to extreme temperatures. Morphological adaptations spread to many organs. In northern animals, there is a large volume of the gastrointestinal tract and a large relative length of the intestine, they deposit more internal fat in omentums and perirenal capsule.

Animals of the arid zone have a number of morphological and functional features of the system of urination and excretion. As early as the beginning of the 20th century. morphologists have discovered differences in the structure of the kidneys of desert animals and animals temperate climate. In hot climate animals, the medulla is more developed due to an increase in the rectal tubular part of the nephron.

For example, at African lion the thickness of the renal medulla is 34 mm, while in the domestic pig it is only 6.5 mm. The ability of the kidneys to concentrate urine is positively correlated with the length of the loop of Hendle.

In addition to structural features in animals of the arid zone, functional features urinary system. So, for a kangaroo rat, a pronounced ability is normal Bladder reabsorb water from secondary urine. In the ascending and descending channels of the loop of Hendle, urea is filtered - a process common to the nodule part of the nephron.

The adaptive functioning of the urinary system is based on neurohumoral regulation with a pronounced hormonal component. In kangaroo rats, the concentration of the hormone vasopressin is increased. So, in the urine of a kangaroo rat, the concentration of this hormone is 50 U / ml, in a laboratory rat - only 5-7 U / ml. In the pituitary tissue of a kangaroo rat, the content of vasopressin is 0.9 U/mg, in a laboratory rat it is three times less (0.3 U/mg). Under water deprivation, differences between animals persist, although the secretory activity of the neurohypophysis increases in both one and the other animal.

The loss of live weight during water deprivation in arid animals is lower. If a camel loses 2-3% of its live weight during a working day, receiving only low-quality hay, then a horse and a donkey under the same conditions will lose 6-8% of their live weight due to dehydration.

The temperature of the habitat has a significant impact on the structure of the skin of animals. In cold climates, the skin is thicker, the coat is thicker, and there are downs. All this helps to reduce the thermal conductivity of the body surface. In animals of a hot climate, the opposite is true: thin skin, sparse hair, low heat-insulating properties of the skin as a whole.

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