Lower mammals are examples. Class mammals

Scientific definition. Mammals- these are representatives of a monophyletic taxon of endothermic amniotes, which differ from reptiles in the presence of hair, three middle auditory ossicles, a mammary gland and a neocortex. The mammalian brain regulates body temperature and the cardiovascular system, including the four-chambered heart.

General information

Mammals are not the most numerous group, but they are surprisingly adaptable to conditions environment. They live in very different natural environments. The brain volume of mammals is larger than that of representatives of other classes of animals. The largest land and sea animals are mammals - elephants on land and whales in the ocean.

There are about 4,500 species of mammals, including giant whales, tiny shrews, and bats. The most large mammals in the world is, growing up to 30 meters in length and weighing up to 200 tons. The largest ungulates are the giraffe (height 5.5 meters, weight 1.5 tons) and white rhinoceros(height 1.8 meters, weight more than two tons). The smartest animals are (starting with the smartest mammal): chimpanzee, gorilla, orangutan, baboon and dolphin.

What mammals lay eggs

Platypuses And echidnas They are the only mammals that lay eggs. These amazing animals live only in Australia, more precisely in its eastern part. Platypuses live in rivers and have webbed feet and a flat, paddle-like tail adapted for swimming. The female platypus lays one or two eggs in a burrow, and feeds the hatched offspring with milk. Female echidnas bury their eggs in a hole, but carry their young in a pouch - where they grow and feed, licking milk from her fur.

Are marsupials the only animals that live in Australia?

No, some species are found in New Guinea and the Solomon Islands in the Pacific Ocean, and two species, the American opossum and the Chilean opossum, live in North and South America, respectively. Mammals that have a pouch for carrying their young are called marsupials. This order includes kangaroos, koalas, wallabies, opossums, wombats, and bandicoots.

How are mammals born?

Placental mammals(most large group mammals) give birth to live young. Inside the female's body developing embryo feeds through a special organ called the placenta. Most mammalian babies go through all stages of development (except marsupials) by the time they are born, although they still require parental care after birth.

The largest group of mammals

Surprisingly, the largest group of mammals is bats. These are the only mammals that can fly and are represented by more than 970 species. Most bats are similar in size to the common mouse. The largest among bats are fruit bats And flying foxes. Many bats are nocturnal hunters of insects, rodents and frogs. To navigate well in space at night, bats use echolocation. They produce high-frequency squeaks that echo off nearby objects.

What animals are called carnivores?

For most animals, the most important activity is searching for food. Unlike plants, which have enough sunlight In order to produce their own food, animals have to constantly look for food. Otherwise they simply will not survive. Different animals need various types food. Herbivores eat plants carnivores- other animals, and omnivores- both plants and animal meat.

Seals, dolphins and whales - marine mammals, whose ancestors lived on land millions of years ago. Their apron limbs turned into pectoral fins, and the rear ones - in a tail with two horizontal blades. Seals and sea ​​lions can move on land; whales and dolphins are only sea animals.

Leopards usually hunt at night. They drag their prey up a tree - away from other animals that feed on carrion, such as hyenas.

A baby kangaroo grows inside its mother's pouch. She protects him from danger until the bag becomes too small for the cub.

Many bats have large ears, which help them catch echoes. The bat pinpoints the location of its prey, such as a moth. Bats roost for the night, hanging upside down and holding onto support with tenacious claws on their paws.

Mammals are the most highly organized class of animals, especially with regard to the nervous system and sensory organs. Currently, about 5,000 species of them live on Earth. However, during the evolution of the class, about 20,000 species arose, most of which became extinct.

Mammals became warm-blooded animals and adapted to different habitats and feeding methods. All this gave rise to a variety of their forms. However, they all have many similarities.

Covers of mammals

The body of mammals has hair, which primarily performs the function of thermoregulation. Among the hairs there are longer and harder ones (awn) and shorter and softer ones (underfur). In some (mainly aquatic) species, hair loss has occurred.

The skin develops many sweat and sebaceous glands. The mammary glands are modified sweat glands. In the vast majority of species, their ducts open on the nipples. All mammals feed their young with milk.

Mammal skeleton

The skeleton of mammals has a number of differences from that of reptiles. In animals, the cervical spine consists of seven vertebrae. The first vertebra is connected to the skull by two condyles, not one. Mammals descended from beast-toothed lizards, which separated from the main branch of reptiles at the beginning of their appearance. Thus, the animal-toothed animals retained a number of amphibian features, including the method of connecting the skull to the vertebrae.

The thoracic vertebrae have ribs, most of which are connected to the sternum. Next come the vertebrae of the lumbar, sacral and caudal sections. The sacral vertebrae are fused.

Most mammals lack caracoids in the shoulder girdle. Many do not have collarbones (usually good runners), which limits the mobility of the limbs to one plane. The limbs of mammals are located under the body, and not on its sides, like in reptiles.

The skull has fewer bones and the brain section is quite large.

Digestive system of mammals

The digestive system of mammals is more differentiated.

The teeth are located in special recesses in the jaw; in most, they are differentiated into incisors, canines, molars, etc. Mammals not only capture and hold prey, but also grind food with their teeth. The salivary glands open into the oral cavity, the secretion of which contains a number of enzymes that digest carbohydrates.

Most have a single-chamber stomach. Only in ruminant artiodactyls does it consist of four sections. The ducts of the liver, gallbladder, and pancreas flow into the duodenum. The intestines are long, especially in herbivores. At the border of the small and large intestines there is a cecum. In the vast majority of mammalian species, the intestine ends in the rectum, which opens to the outside with a separate anus. However, monotremes retain a cloaca.

Mammalian circulatory system

IN circulatory system In mammals, there is a complete separation of the venous and arterial blood flow. To do this, the ventricle of their heart is completely divided by a septum into the left (arterial) and right (venous) halves. Thus, the heart becomes four-chambered. In addition, only one (left) aortic arch remains, which also eliminates mixing of blood. The same thing happened in birds in the process of evolution. However, they preserved the right aortic arch. Birds evolved from another group of ancient reptiles.

Arterial blood is pushed from the left ventricle into the aorta, from which the carotid arteries and the dorsal aorta originate. Smaller arteries branch off from them. Venous blood from the body's organs collects in the anterior and posterior vena cava, which drain into the right atrium. This is a large circle of blood circulation.

The pulmonary circulation begins in the right ventricle, from which the pulmonary artery emerges, carrying venous blood to the lungs. It is divided into two branches. From the lungs, arterial blood collects in the pulmonary vein, which drains into the left atrium.

Mammalian red blood cells do not contain nuclei, which allows for more efficient oxygen transport.

Respiratory system of mammals

All mammals, including those that have switched to an aquatic lifestyle, breathe through their lungs. The lungs have an alveolar structure, when the bronchi entering them branch into smaller and smaller ones, ending in alveolar vesicles, in which gas exchange occurs.

Inhalation and exhalation in mammals is carried out due to the movement of the intercostal muscles and the diaphragm. The diaphragm is a muscular septum separating the chest and abdominal cavities.

The accessory organs of the mammalian respiratory system are the trachea and bronchi. The trachea begins in the pharynx. The beginning of the trachea is called the larynx, it contains vocal cords.

Mammalian excretory system

In mammals, pelvic kidneys develop, from which ureters extend into the common bladder. The bladder opens to the outside with an independent opening (with the exception of monotremes).

The mammalian kidney consists of a superficial cortex and an inner medulla. Filtration of decay products and excess water from the blood occurs in the cortex, consisting of thin tubes ending in Bowman's capsules. The medulla consists of collecting ducts.

The main excretion product is urea.

Nervous system and sensory organs

In mammals, the forebrain cortex is well developed in the brain; most have convolutions that increase its surface. The behavior is complex, for many conditioned reflexes easy to form. The cerebellum, which is responsible for the complexity of movements, is also well developed.

The senses of smell and hearing play an important role in the life of mammals. The outer ear appears, consisting of the auricle and auditory canal. The middle ear is separated from it by the eardrum.

Vision in mammals is developed, but worse than in birds. This is especially true for color perception.

Many animals have long, coarse hairs (whiskers) on their faces - vibrissae. These are the organs of touch.

Dolphins and bats are capable of echolocation. They make sounds that are reflected from surrounding objects and return to the animal, which, having caught them, determines the distance to objects in conditions of poor visibility.

Mammal Reproduction

Mammals, like all land vertebrates, are characterized by internal fertilization. In most species, females have a uterus in which the embryo develops and a placenta is formed, through which the embryo is nourished. Pregnancy is quite long (this does not apply to marsupials and oviparous animals).

Characterized by care for the offspring, a long period of individual development (usually correlated with the size of the animal and the complexity of behavior - the larger or more complex, the longer the childhood period). All mammals feed their young with milk.

Mammal taxonomy

Previously, the class Mammals was divided into three subclasses, representatives of which live in our time. These are Oviparous (aka Monotremes), Marsupials and Placentals.

Oviparous species include the platypus and echidnas, which live in Australia and its surrounding islands. These animals do not have viviparity. Instead, they lay eggs (but by the time the egg is laid, the embryo in the egg is already quite mature). They have a cloaca, caracoids, and a less constant body temperature. Thus, oviparous animals combine the characteristics of mammals and reptiles.

Marsupials are common in Australia, South and partly North America. In Australia, due to its isolation, in the process of evolution many species of marsupials (marsupial predators, rodents, herbivores) similar to placentals appeared. A typical representative is a kangaroo. Marsupials do not form a complete placenta. The baby is born very premature and is carried to term in the pouch (a special fold of skin on the abdomen), attached to the nipple.

Placental mammals are the most diverse. Their taxonomy is quite complex and has recently been somewhat changed. Thus, pinniped seals and walruses, which were previously classified as a separate order, are today assigned to the order Predatory.

In total, there are about 25 orders of mammals, whose representatives live in our time. The most numerous order is Rodents (more than 2 thousand species). Its representatives are distributed everywhere. Other orders: Lagomorphs, Chiroptera, Insectivores, Carnivores, Proboscideans, Artiodactyls and Odd-toed ungulates, Primates, Cetaceans, etc.

The most successful group in the animal kingdom are mammals. In this article we will briefly talk about the characteristics of these animals, clarify which orders belong to mammals, and determine their habitats.

Features of mammals

This class of vertebrates belongs to the superclass of tetrapods, in which there are about 5.5 thousand species, including Homo sapiens. The main feature of the representatives of the “Mammals” group is feeding their young with milk.
In addition, there are the following signs:

• warm-blooded;
• live birth;
• the body is covered with hair, sweat and sebaceous glands, and horny formations are developed;
• the skull has a zygomatic arch;
• the spine is clearly divided into five sections;
• vertebrae of platycelial type;
• subcutaneous muscles are highly developed, there is a diaphragm;
• highly developed nervous system, which allows you to quickly respond to stimuli from external environment;
• special structure of the hearing organ;
• the lungs have an alveolar structure;
• the heart is four chambered, the blood circulation is divided into two circles;
• unique structure of jaws and teeth.

The physiology of mammals is not particularly different from other four-legged representatives, but due to the high development of certain organ systems, this class is considered the highest highly organized among animals.

The Latin name of this class is Mammalia, which is derived from the Latin “mamma” – breast, udder. Russian word“mammals” means milk-feeding.

Spreading

Representatives of the class can be found everywhere. The only places where there are no mammals are the deep ocean and Antarctica, although seals and whales can be found off its coast.

Many subtypes are limited in distribution due to their attachment to environmental conditions. For many animals, temperature, soil and orographic conditions, as well as the availability of food are important.

The separate class “Mammals” was first described by Carl Linnaeus in 1758. At that time, there were 184 species; in modern times, all species are divided into 26-29 orders, which consist of 153 families, divided into 1229 genera.

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According to the traditional classification, this class of vertebrates is divided into the subclasses “Primal Beasts” (Prototheria) and “Beasts” (Theria). The latter, in turn, are divided into two infraclasses: Marsupials and Placentals.

Rice. 1. Classification.

Description of orders of mammals

All representatives of the class are quite diverse in appearance. The traditional body structure, which consists of a head, neck, torso, two pairs of limbs and a tail, varies in the ratio of shapes and sizes. So, a shining example Such variations may include the long neck of a giraffe, and the absence of a neck in whales.

Rice. 2. External structure.

The order Chiroptera is very different from other mammals due to the transformation of the forelimbs into wings. Due to this, in the popular classification, bats were classified as birds.

The record holders for size and body weight are: the dwarf shrew (weight up to 1.7 g, length up to 4.5 cm), savannah elephant (weight up to 5 tons, shoulder height up to 4 m), blue whale(length - 33 m, weight - up to 1.5 tons).

The list of mammals in Russia includes about 300 species. You can see their list in the following table:

Squad	Family	Genus	Representatives
			Common flying squirrel
			Common squirrel
		Chipmunks	Asian chipmunk
			Long-tailed ground squirrel, Caucasian ground squirrel
			Steppe, Kamchatka, Altai marmot
		Hazel, forest, garden dormouse
		Sleepyheads	Sonya the Regiment
	Beavers		Canadian beaver, river beaver
	Mousebirds		Forest mouse, steppe mouse, Caucasian mouse, etc.
	Jerboa	Jerboas	Large and small jerboas
	Mole rats		Common mole rat, Ural
	Hamsters		Common hamster
		Mole voles	Mole voles
			Forest, Siberian, Promethean voles
		Oriental, forest, house mice	Field, small, forest, house mice
			Gray and black rats
Lagomorpha	Zaitsevy		Brown hare, mountain hare, bush hare
			Wild rabbit
			Altai, northern, small pika
Insectivores		Common hedgehogs	European hedgehog
		Eared hedgehogs	long eared hedgehog
	Moles	Common moles
		Muskrat	Russian muskrat
	Shrews	Shrews	Siberian, long-tailed shrew
		Shrews	Far Eastern, giant, and average shrews
Chiroptera	Horseshoe-nosed	Horseshoe bats	Southern, great horseshoe bat
	Smooth-nosed		Long-eared, Amur bat
		Vechernitsy	Red-haired, oriental noctule
			Desert leather, leather jackets
	Raccoons		Raccoon
		Raccoon dogs	Raccoon dog
		Wolves and dogs	Jackal, wolf
			Fox, corsac dog
	Bearish		White, brown bear
	Marten		Kharza, sable, martens
		Caresses and hori	Weasel, ermine
			Forest, steppe cat
Odd-toed ungulates	Equine		wild horse
Artiodactyls			Wild boar
		Deer, roe deer, moose	Reindeer, European roe deer, elk
	Bovids	Mountain goats, sheep	Siberian goat, mountain sheep
Cetaceans	Dolphinidae	Common dolphins, killer whales, whales	Dolphins, killer whales, whales

Rice. 3. Diversity of mammals.

What have we learned?

The most highly developed group of animals are mammals. Representatives of this class can be found everywhere. They gained a leading position due to a number of their physiological and external features. Their main characteristics are feeding their offspring with milk, as well as being warm-blooded.

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Mammals are warm-blooded vertebrates. Their heart is four-chambered. Skin with a large number iron Hair development. The cubs are fed with milk, which is produced in the mammary glands of the female. The central nervous system is highly developed. Mammals inhabit land, seas and fresh waters. All of them descended from land-based ancestors. More than 4000 species are known.

Most mammals are four-legged animals. The body of these animals is raised high above the ground. The limbs have the same sections as the limbs of amphibians and reptiles, but are located not on the sides of the body, but under it. Such structural features contribute to more advanced movement on land. Mammals have a well-defined neck. The tail is usually small in size and... sharply separated from the body. The body is covered with hair. The hair on the body is not uniform. There is an undercoat (protects the body from cooling) and a guard (prevents the undercoat from matting and protects it from contamination). Shedding, which is inherent in mammals, is expressed in the loss of old hair and its replacement with new ones. Most animals have two molts during the year - in spring and autumn. Hair consists of horny substance. Horny formations are nails, claws, and hooves. The skin of mammals is elastic and contains sebaceous, sweat, mammary and other glands. The secretions of the sebaceous glands lubricate the skin and hair, making them elastic and resistant to wetness. Sweat glands secrete sweat, the evaporation of which from the surface of the body protects the body from overheating. Mammary glands are present only in females and function during the period of feeding the young.

Most mammals have five-fingered limbs. However, due to adaptation to movement in different environments changes in their structure are observed. For example, in whales and dolphins, the forelimbs have changed into flippers, in bats - into wings, and in moles they have the appearance of spatulas.

The mouth of mammals is surrounded by fleshy lips. The teeth located in the mouth serve not only to hold prey, but also to grind food, and therefore they are differentiated into incisors, canines and molars. The teeth have roots with which they are strengthened in the sockets of the jaws. Above the mouth there is a nose with a pair of external nasal openings - nostrils. The eyes have well-developed eyelids. The nictitating membrane (third eyelid) is underdeveloped in mammals. Of all animals, only mammals have an external ear - the auricle.

The skeleton of mammals is similar to that of reptiles and consists of the same sections. However, there are some differences. For example, the skull of mammals is larger than that of reptiles, which is associated with the larger size of the brain. Mammals are characterized by the presence of seven cervical vertebrae (38). The thoracic vertebrae (usually 12-15) together with the ribs and sternum form a strong rib cage. The massive vertebrae of the lumbar region are movably articulated with each other. The number of lumbar vertebrae can be from 2 to 9. The sacral section (3-4 vertebrae) fuses with the pelvic bones. The number of vertebrae in the caudal region varies significantly and can be from 3 to 49. The girdle of the forelimbs of mammals consists of two shoulder blades with crow bones attached to them and two clavicles. The girdle of the hind limbs - the pelvis - is formed by three pairs of usually fused pelvic bones. The skeletons of the limbs of mammals are similar to those of reptiles. Most mammals have well-developed muscles of the back, limbs and their girdles.

Digestive system.

Almost all mammals bite off food with their teeth and chew it. In this case, the food mass is abundantly moistened with saliva secreted into the oral cavity by the salivary glands. Here, along with grinding, food digestion begins. The stomach of most mammals is single-chambered. In its walls there are glands that secrete gastric juice. The intestine is divided into small, large and rectal intestines. In the intestines of mammals, as well as in reptiles, the food mass is exposed to the action of digestive juices secreted by the intestinal glands, liver and pancreas. Remains of undigested food are removed from the rectum through the anus.

In all animals, the chest cavity is separated from the abdominal cavity by a muscular septum - the diaphragm. It protrudes into the chest cavity with a wide dome and is adjacent to the lungs.

Breath.

Mammals breathe atmospheric air. Respiratory system consists of the nasal cavity, larynx, trachea, lungs, characterized by a large branching of the bronchi, which end in numerous alveoli (pulmonary vesicles), intertwined with a network of capillaries. Inhalation and exhalation are carried out by contracting and relaxing the intercostal muscles and the diaphragm.

Circulatory system. Like birds, the mammalian heart consists of four chambers: two atria and two ventricles. Arterial blood does not mix with venous blood. Blood flows through the body in two circulatory circles. The mammalian heart provides intense blood flow and supply of body tissues with oxygen and nutrients, as well as the release of tissue cells from waste products.

The excretory organs of mammals are the kidneys and skin. A pair of bean-shaped kidneys are located in the abdominal cavity on the sides of the lumbar vertebrae. The resulting urine enters the bladder through two ureters, and from there it is periodically discharged through the urethra. Sweat released from the sweat glands of the skin also removes large number salts from the body.

Metabolism. The more advanced structure of the digestive organs, lungs, heart and others ensures a high level of metabolism in animals. Due to this, the body temperature of mammals is constant and high (37-38°C).

Nervous system has a structure characteristic of all vertebrates. Mammals have a well-developed cerebral cortex. Its surface increases significantly due to the formation of a large number of folds - convolutions. In addition to the forebrain, the cerebellum is well developed in mammals.

Sense organs. Mammals have well-developed senses: olfactory, auditory, visual, tactile and gustatory. The organs of vision are better developed in animals living in open areas. Animals living in the forest have better developed senses of smell and hearing. The organs of touch - tactile hairs - are located on the upper lip, cheeks, and above the eyes.

Reproduction and development of mammals. Mammals are dioecious animals. In the reproductive organs of the female - the ovaries - eggs develop, in the reproductive organs of the male - testes - sperm. Fertilization in mammals is internal. Mature cells enter the paired oviduct, where fertilization occurs. Both oviducts open into a special organ of the female reproductive system - the uterus, which is found only in mammals. The uterus is a muscular sac, the walls of which can stretch greatly. The egg that has begun to divide attaches to the wall of the uterus, and all further development of the fetus occurs in this organ. In the uterus, the membrane of the embryo is in close contact with its wall. At the point of contact, a baby's place, or placenta, is formed. The embryo is connected to the placenta by the umbilical cord, inside which its blood vessels pass. In the placenta, through the walls of blood vessels, nutrients and oxygen enter the blood of the fetus from the mother’s blood, and carbon dioxide and other waste products harmful to the fetus are removed. The duration of development of the embryo in the uterus varies among different mammals (from several days to 1.5 years). At a certain stage, the mammalian embryo has the rudiments of gills and is similar in many other characteristics to the embryos of amphibians and reptiles.

Mammals have a well-developed instinct to care for their offspring. Female mothers feed their cubs with milk, warm them with their bodies, protect them from enemies, and teach them to look for food. Caring for offspring is especially highly developed in mammals whose young are born helpless (for example, a dog, a cat).

Origin of mammals.

The similarity of modern mammals to reptiles, especially in the early stages of embryonic development, indicates the close relationship of these groups of animals and suggests that mammals evolved from ancient reptiles (39). In addition, even now in Australia and on the adjacent islands there live oviparous mammals, which, in their structure and reproductive characteristics, occupy an intermediate position between reptiles and mammals. These include representatives of the oviparous order, or primal beast - platypus and echidna.

When they reproduce, they lay eggs covered with a durable shell that protects the contents of the egg from drying out. The female platypus lays 1 - 2 eggs in a burrow, which she then incubates. The echidna carries a single egg in a special pouch, which is a fold of skin on the ventral side of the body. The oviparous cubs that emerge from the egg are fed with milk.

Order Marsupials. These include kangaroos, marsupial wolves, marsupial bear koala, marsupial anteaters. In marsupials, unlike primitive animals, the development of the embryo occurs in the mother’s body, in the uterus. But the baby's place, or placenta, is absent, and therefore the baby does not stay in the mother's body for long (for example, in a kangaroo). The baby is born underdeveloped. Further development it occurs in a special fold of skin on the mother’s abdomen - the bursa. Primordial animals and marsupials are an ancient group of mammals, widespread in the past.

The importance of mammals and the protection of beneficial animals.

The significance of mammals for humans is very diverse. Undoubtedly harmful include many rodents that harm crops and destroy food supplies. These animals can also spread dangerous human diseases. Known harm The human economy is harmed by some predatory mammals (in our country, the wolf) that attack livestock.

The benefit of wild mammals is to obtain valuable meat, skin and fur from them, and also fat from sea animals. In the USSR, the main game animals are squirrel, sable, muskrat, fox, arctic fox, and mole.

In order to enrich the fauna (fauna is called species composition fauna of any country or region) in our country, measures are constantly being taken for acclimatization (introduction from other areas or countries) and resettlement of useful animals.

In the USSR, many species of mammals are protected by law, the hunting of which is completely prohibited.

The main orders of placental mammals:

Units	Characteristic features of units	Representatives
Insectivores	The teeth are of the same type, sharply tuberculate. The anterior end of the head is extended into a proboscis. The cerebral cortex is devoid of convolutions	Mole, hedgehog, muskrat
Chiroptera	The forelimbs are transformed into wings (formed by leathery membranes). Bones are thin and light (adaptation for flight)	Ushan, red-headed noctule
	The incisors are strongly developed, there are no fangs. They reproduce very quickly	Squirrel, beaver, mouse, chipmunk
Lagomorpha	The structure of the teeth is similar to rodents. In contrast, they have two pairs of incisors, one of which is located behind the other	Hares, rabbit
	They feed mainly on live food. The fangs are highly developed and there are carnassial teeth	Wolf, fox, bear
Pinnipeds	They spend most of their life in water. Both pairs of limbs are converted into flippers	Walrus, seal, cat
Cetaceans	They live in water. The forelimbs are transformed into flippers, the hind limbs are reduced

Mammals are the most highly organized and youngest class of animals, which are characterized by the following characteristics:

• hairline
• skin glands
• warm-blooded
• constant body temperature
• developed cerebral cortex
• live birth
• caring for offspring
• difficult behavior.

All this allowed mammals to gain a dominant position in the animal world. They live in all environments: on land, in soil, in water, in the air, on trees, in all natural areas.

Ecological types of mammals ( life forms) are determined by their habitat: aquatic and semi-aquatic have a streamlined fish-like body shape, flippers or webbed feet; Ungulates living in open areas have high slender legs, a dense body, and a long, mobile neck. Therefore, among representatives of different subclasses, orders, families, there may be similar life forms due to the same living conditions. This natural phenomenon is called convergence, and signs of similarity are called homologous.

A highly developed nervous system allows mammals to better adapt to environmental conditions and make fuller use of natural resources when obtaining food, when protecting themselves from enemies, and when constructing burrows and shelters.

The transfer of experience, training of young animals, foreseeing the course of many events made it possible for animals to better preserve their offspring and occupy new territories.

Their population structure is different: some consist of those living on permanent place alone or in families, others roam in a herd or flock. A rather complex system of subordination plays an important role when selection for the best organization of a herd or flock takes place.

In food chains, mammals also occupy different positions: some are primary consumers of plant food (consumers of the first order), others are carnivorous, peaceful (insect- and planktivorous - consumers of the second order), others are predatory (attacking large active prey - consumers of the second and third orders). III order). Mixed nutrition is characteristic of primates, carnivores and rodents. There is a very close relationship between animals and plants, which, on the one hand, are objects of consumption (in this case, fruits and seeds are often distributed), and on the other hand, they protect themselves from them with the help of thorns, thorns, an unpleasant odor, and a bitter taste.

Of the entire animal world, humans are closely related to mammals: 15 species are domestic animals, in addition, 20 species are fur-bearing animals bred in cages, as well as laboratory animals (mice, rats, guinea pigs, etc.). Domestication continues to this day: new breeds are bred and old ones are improved through hybridization with wild animals.

Hunting and sea fishing and the acclimatization of animals from other continents play a major role in the human economy.

At the same time, there are harmful animals that attack humans and domestic animals, carriers of diseases, pests of crops, gardens, and food supplies. To reduce the negative impact of these animals on nature and the human economy, we study the structure of their populations, population dynamics, food resources - all this data is entered into a computer, as a result of which they receive a forecast for the future, develop recommendations that determine ways and means of influencing the population in order to limit its harmfulness.

The number of mammal species under the influence of human activity is constantly decreasing as a result of hunting, the destruction of predators, destruction of the habitat of wild animals, protection of agricultural plants from rodents (treating fields with pesticides), forest and steppe fires, etc.

The Red Book of the USSR (1984) lists 54 species and 40 subspecies of animals. To protect them, nature reserves, wildlife sanctuaries, and national parks have been organized, their breeding has been organized, and hunting and fishing are prohibited. Thanks to these events, the bison, kulan, Bukhara deer, tiger, eastern leopard, and goral were saved from extinction; The numbers of saiga, sable, and beaver have been restored.

In the modern fauna there are 4000-4500 species of mammals, including 359 species within Russia and 101 in Ukraine. Mammals are distributed on all continents, with the exception of Antarctica, in terrestrial, marine and freshwater biocenoses. Some species actively fly in the air, others live in the soil. Most species live in various terrestrial biocenoses. Due to adaptation to life in different conditions appearance These animals are very different, but they differ sharply from all others in the features of their internal and external structure.

Class characteristics

Mammals, or animals, represent the highest class of vertebrates, whose organs, especially the forebrain cortex, are modern stage development have reached the highest differentiation.

Thanks to the progressive development of the central nervous system, warm-bloodedness, the presence of hair, bearing young in the mother’s body and feeding them with milk, mammals won the competition with reptiles and other vertebrates and firmly conquered not only land, but also other habitats.

Coverings of the body. Like all vertebrates, mammalian skin consists of a multilayered epidermis and corium. The outside of the body is covered with epidermis, the upper stratum corneum of which constantly falls off in the form of individual dead cells. Renewal of the epidermis occurs due to cell division of the Malpighian layer. Corium is constructed from fibrous connective tissue, the deep layers of which (the so-called subcutaneous tissue) contain fat cells. In addition, mammalian skin is rich in sweat glands, and many species have scent glands.

All mammals are characterized by the presence of mammary glands, which are modified sweat glands. The ducts of the mammary glands open in certain areas of the skin of the abdominal side. With the exception of monotremes, all mammalian mammary glands are equipped with nipples. Their number varies from 1 to 14 pairs. The mammary glands secrete milk, which is fed to newborns (hence the name of the class).

Of the horny formations of the skin (hair, nails, claws, hooves), hair is the most typical for mammals. Most animals have hair developed over the entire surface of the body (absent on the lips, and in some, on the soles). Mammalian hair is heterogeneous. Large, long, hard, sticking hairs are called vibrissae; they are located at the end of the muzzle, belly, limbs, serve as organs of touch, their bases are connected to nerve endings.

Hair consists of a trunk and a root. The trunk is built of a heart-shaped substance covered with a cortical layer and a skin on the outside. There is air in the hair cavity. The hair root ends in a bulb, the base of which includes the hair papilla. It is rich in blood vessels and serves to nourish the hair. The hair papilla is located in the hair follicle, into which the ducts of the sebaceous glands open, secreting a fatty substance that lubricates the hair. The skin of mammals is rich in sebaceous and sweat glands. The latter produce sweat, due to which thermoregulation is carried out. In temperate and northern latitudes, most species change their hair coat twice a year, molting occurs in autumn and spring.

Mammals, like birds, are warm-blooded animals. Their body temperature is constant (in different species it ranges from 37 to 40 °C), only in oviparous animals the body temperature largely depends on the external temperature and ranges from 25-36 °C. Perfect thermoregulation of most mammals is ensured by the presence of sweat glands, hair, subcutaneous fat, and breathing also takes part in thermoregulation.

Skeleton. The skeleton consists of the skull, spine, limb girdles and bones of paired limbs. The mammalian skull is distinguished by a large volume of the cranium, or braincase. Its bones fuse at the sutures quite late, so as the animal grows, the brain can increase in volume. The lower jaw consists of only one (dentary) bone and is attached to the paired temporal bone. The other two jaw bones became auditory ossicles - the malleus and the incus. Thus, mammals have three auditory ossicles - the stapes, the malleus and the incus, while amphibians, reptiles and birds have only one - the stapes (see Table 18).

In the skeleton of mammals, there is a clear division of the spine into five sections: cervical, thoracic, lumbar, sacral and caudal. Characteristically, there is a constant number of cervical vertebrae (7). On the front side of one of the two cervical vertebrae - the atlas - there are two articular surfaces, like in amphibians. The ribs are attached to the vertebrae of the thoracic region; with their cartilaginous part they are connected to the chest bone, or sternum, forming the rib cage. The sacral vertebrae are fused together and connected to the bones of the pelvic girdle. The number of caudal vertebrae ranges from 3 (in the gibbon) to 49 (in the long-tailed lizard). The degree of mobility of individual vertebrae varies. The vertebrae are the most mobile in small running and climbing animals, so their body can bend in different directions, curl up into a ball, etc. The mobility of the vertebrae is due to the articulation of their flat surfaces with the cartilage discs (menisci) located between the vertebrae.

The girdle of the forelimbs consists of paired shoulder blades and clavicles (the latter are not developed in many species). The forelimb includes the shoulder, two bones of the forearm (ulna and radius) and the hand with phalanges of the fingers.

The hind limb girdle consists of three paired large bones, which in most mammals are fused with the sacral vertebrae. The hind limb includes the femur, two tibia bones (large and small) and a foot with phalanges. As a result of adaptation to different types of movement, the skeleton of the limbs in different mammals has changed greatly. In bats, very long phalanges of fingers support the tense membrane-plane of the wing, the single-toed legs of a horse are adapted for fast running, the flippers of cetaceans are adapted for swimming, the hind legs of kangaroos and jerboas are adapted for jumping, etc.

Muscular system. In mammals it is extremely developed, complex and contains several hundred individual specialized muscles. The chewing and facial muscles are highly developed, especially in monkeys and humans, as well as the subcutaneous muscles. A typical muscular formation of mammals is the thoraco-abdominal barrier, or diaphragm (a muscular partition separating the chest cavity from the abdominal cavity). The diaphragm plays a big role in breathing. When the diaphragm lowers and rises, the volume of the chest changes and intensive ventilation of the lungs occurs.

Digestive system. The digestive organs begin with the preoral cavity, located between the fleshy lips (they are developed only in mammals) and the jaws. On the upper and lower jaws there are teeth differentiated into certain groups depending on the type of nutrition. There are incisors, canines and molars. These groups of teeth perform various functions: biting and grinding food, capturing and killing prey, etc. The structure of the teeth is associated with the animal’s lifestyle. A tooth consists of 1-2 roots and a crown. Teeth are made of dentin, cement and enamel, located in the sockets of the jaw bones. The echidna, anteater and some cetaceans lack teeth. During the development of an animal, two changes of teeth occur - milk and permanent.

The tongue is located at the bottom of the oral cavity and is involved in chewing and swallowing food. The surface of the tongue is covered with numerous taste buds. The ducts of three pairs of large ones open into the oral cavity salivary glands. Saliva not only moisturizes food - it contains enzymes that, already during chewing of food, break down starch into glucose. Thus, food processing begins in the oral cavity.

Next, the food enters the pharynx, esophagus, and from there into the stomach. The structure of the stomach, consisting of the cardiac and pyloric sections, is varied, which is associated with the nature of the food. There are many glands in the walls of the stomach. The gastric juice secreted by the glands contains hydrochloric acid and enzymes (pepsin, lipase, etc.). In the stomach, the digestion process continues. Especially complex structure has the stomach of ruminant ungulates, which eat large amounts of hard-to-digest rough plant food. Digestion of food continues in the duodenum, where the ducts of the liver and pancreas flow. In the small intestines, the breakdown of proteins, fats and carbohydrates ends and the absorption of essential nutrients occurs. At the border between the small and large intestines in some mammals there is a cecum and a vermiform appendix. Undigested food remains enter the large intestine and are removed through the rectum.

Respiratory system. The respiratory organs of all mammals begin with the nasal cavity, which has respiratory and olfactory sections. When breathing, air from the nasal cavity enters the larynx, which is supported by several laryngeal cartilages formed by the second and third gill arches. The vocal cords are stretched between the thyroid and arytenoid cartilages. From the larynx, air enters the trachea, which divides into two bronchi. Each of the bronchi enters one of the lungs and branches there, forming a dense network. The smallest pulmonary passages - bronchioles - open into dilated pulmonary vesicles, or alveoli. In the walls of the alveoli, the thinnest blood vessels branch - capillaries, in which gas exchange occurs. The lungs have a complex cellular structure, their respiratory surface is 50-100 times greater than the surface of the body. Contractions of the diaphragm and intercostal muscles increase the volume of the thoracic cavity, air is forced into the lungs, and inhalation occurs. When the muscles relax, the volume of the thoracic cavity decreases and exhalation occurs.

Excretory system. It is characteristic of the excretory organs that the bladder opens not into the cloaca, but into the urethra. Paired ureters open into the bladder, originating from paired bean-shaped secondary kidneys located in the lumbar region under the spine.

Circulatory system mammals are close to the circulatory system of birds: the heart is four-chambered, the large and small circles of blood circulation are completely separated, but there is not a right, but a left aortic arch (in birds - a right aortic arch). Red blood cells in their formed state lack nuclei.

Nervous system and sensory organs. The nervous system has the same sections as in other vertebrates (forebrain, interstitial, midbrain, cerebellum and medulla oblongata), but its level of development is much higher. The forebrain, which covers the midbrain and cerebellum, reaches its greatest size and complexity. The surface of the cerebral cortex increases due to convolutions and grooves, the number of which is especially large in higher mammals. The cerebral cortex contains centers of higher nervous activity that coordinate the work of other parts of the brain and determine the complex behavior of mammals. The cerebellum, which is associated with maintaining muscle tone, balance and proportionality of movements.

The level of development of sensory organs depends on the lifestyle of animals and obtaining food. For inhabitants of open spaces, vision is of the utmost importance, for nocturnal and twilight animals, inhabitants of forests and thickets of bushes, ponds and burrows - smell and hearing.

The sense of smell in mammals is more developed than in other groups of terrestrial vertebrates. In the upper posterior part of the nasal cavity, a complex system of olfactory conchae is developed, their surface is covered with a mucous membrane of the olfactory epithelium. The complexity of the structure of the olfactory shells corresponds to the acuteness of smell. The organs of taste are the taste buds in the mucous membrane of the mouth and tongue.

The hearing organs are well developed in the vast majority of mammals. The hearing organ consists of three sections: the outer, middle and inner ear. The outer ear (pinna) and external auditory canal represent a kind of antenna-filter that amplifies sounds that are important for the animal and attenuates constant noise. In aquatic mammals and soil dwellers, the auricle is reduced. There are three auditory ossicles in the middle ear, which ensure perfect transmission of sound waves to the inner ear. The inner ear consists of the auditory and vestibular sections.

In the auditory department, the spirally twisted cochlea with several thousand of the finest fibers, resonating when perceiving sound, is very developed. The vestibular section includes three semicircular canals and an oval sac; it serves as an organ of balance and perception of the spatial position of the body. The hearing range of mammals is much wider than that of birds and reptiles; the auditory cochlea allows mammals to distinguish the highest frequencies.

The eye of mammals is covered with fibrous tissue - the sclera, which in front turns into a transparent cornea. Under the sclera there is a choroid with blood vessels supplying the eye; in front it thickens and forms the iris. The iris is located directly in front of the lens, plays the role of a diaphragm, and regulates the illumination of the retina by changing the size of the pupil. The lens is lens-shaped and is enlarged in nocturnal and crepuscular animals. Accommodation is achieved only as a result of changing the shape of the lens. Adjacent to the inner side of the choroid is the retina, a light-sensitive layer consisting of receptors (rods and cones) and several types of neurons. Many mammals have the ability to distinguish colors; Color vision is well developed in humans and higher primates. Horses, for example, recognize four colors. Nocturnal animals have well-developed vision, in particular cats can distinguish six primary colors and 25 shades gray. In animals that lead an underground lifestyle, vision is reduced (some moles, mole rats, etc.).

Reproduction. The reproductive organs in the male are represented by paired testes, in the female - by paired ovaries. Fertilization is internal. The fertilized egg begins to divide and descends through the oviduct into the uterus, where intrauterine development of the embryo occurs. In most mammals, during the development of the embryo, the placenta is formed in the uterus, through which gas exchange, nutrition of the embryo and excretion of metabolic products occur. In oviparous mammals the placenta is absent; in marsupials it is rudimentary. The vast majority of mammals are characterized by viviparity and only oviparous mammals lay large, yolk-rich eggs. All mammals feed their young with milk. They are distinguished by a high degree of care for their offspring. Most mammals build special nests, and even after finishing milk feeding, they take long and diligent care of the young and train them.

Taxonomy. According to the characteristics of reproduction and organization, modern mammals are divided into three subclasses: cloacal (Monotremata), marsupials (Marsupialia) and placentals (Placentalia) (Table 20).

Table 20. Division of mammals according to characteristics of reproduction and organization
Subclass	Number of types)	Spreading	Characteristic signs	Lifestyle
Oviparous or cloacal	4 (platypus and 3 types of echidnas)	Australia, New Guinea and Tasmania	Primitive: there are coracoids in the shoulder girdle; there is a cloaca; lay eggs. Progressive: hair, mammary glands (however, there are no nipples, the ducts of the glands open on the “milky” field of the mother’s skin, the cubs lick it off). Body temperature is low (25-30 °C), largely depends on the external temperature	The platypus lives along the banks of water bodies, swims and dives well, and feeds on aquatic invertebrates (insects, crustaceans, mollusks, worms). Cubs have milk teeth, while adults have toothless, flat jaws. The paws have webs and claws. Eggs with a diameter of 15-20 mm, in a parchment-like shell, laid in a hole, incubated for 7-10 days
Marsupials	About 250	Australia, New Guinea Islands, etc.; South and North America	Primitive: the placenta is underdeveloped, the gestation period is very short, and the presence of a pouch on the abdomen is characteristic, in which the development of the cubs ends. Progressive: live birth; mammary glands with nipples, coracoids fused with the shoulder blades. Body temperature is about 36 °C. The teeth are not replaced (correspond to the milk teeth of higher mammals)	There are insectivores (marsupial mice, moles), carnivores (marsupial wolves, martens), herbivores (kangaroos, marsupial bears - koalas)
Higher, or placental	About 4000	All continents except Antarctica, as well as seas and oceans	The embryo develops in the uterus, where, due to the fusion of two amniotic membranes, the placenta is formed, forming a spongy chorion; chorionic villi fuses with the uterine epithelium; They give birth to fully formed cubs that are able to feed on mother's milk independently. There are milk and permanent teeth	There are insectivores, carnivores, herbivores; a total of 17 orders (the main ones are insectivores, chiropterans, rodents, lagomorphs, carnivores, pinnipeds, cetaceans, artiodactyls, equids, proboscis, primates)

Monotremes, or cloacals (platypus, echidna, echidna), live only in Australia. They lay fairly large eggs with a lot of nutrients. After fertilization, the egg remains in the mother’s reproductive tract for a long time (16-27 days), during which time the embryo develops in it. The period of incubation or carrying an egg to term is short and does not exceed 10 days. Monotremes have no teeth. The intestines and genitourinary organs open into the cloaca. There are no nipples. The shoulder girdle is similar to that of reptiles. Body temperature ranges from 24 to 34 °C. The paired oviducts (fallopian tubes) and the uterus pass into the urogenital sinus. The listed features indicate a significant primitiveness of the structure of cloacals and their closeness to ancestors common with reptiles.

Lower animals, or marsupials (kangaroos, marsupial wolves, marsupial moles, etc.), live in Australia and South America. They do not have a placenta (except for some species), the cubs are born underdeveloped and are born in a pouch, hanging on the nipple (for example, a giant kangaroo weighing 60-70 kg gives birth to a calf weighing only 80 g, the size of walnut, in other marsupials newborns are even smaller). Newborn marsupials independently crawl into their mother’s pouch, where they find the nipple. As soon as the baby finds the nipple, the latter swells and fills the newborn's oral cavity. The cub feeds on milk and lives in the mother's pouch from 60 days in small species to 250 days in large species. The marsupial brain is primitive. There are two uteruses and two vaginas. The teeth, except for the front molar, are not replaced. Body temperature is not strictly constant, but higher than that of monotremes.

TO higher beasts, or placental, includes the vast majority of modern mammals. Their peculiarities are that the embryo is nourished through the placenta. The baby is born more or less developed and can suckle milk. The brain is well developed. There are two changes of teeth.

Modern placentals are divided into 16 orders. The most important of them are: insectivores, chiropterans, edentates, rodents, carnivores, pinnipeds, cetaceans, ungulates, proboscis, primates. The order of insectivores, which is very ancient in origin, is characterized by the most primitive structure. One of the most highly organized orders (although retaining many primitive structural features) are primates. The characteristic features of the main orders of mammals are given in Table. 21.

There are suborders of lower primates, or prosimians (tupai, lemurs, tarsiers), and higher primates. Among the latter, a group of broad-nosed (marmosets, howler monkeys, arachnids and woolly monkeys), narrow-nosed (monkeys, macaques and baboons) and great apes (orangutans, chimpanzees, gorillas) is distinguished. All groups of modern primates are characterized high level specializations.

Apes are the most highly developed animals. They are distinguished by the complex structure of the cerebral cortex and do not have cheek pouches, a tail or ischial calluses. The vermiform appendix of the cecum is long (20-25 cm). They have four blood types, just like humans.

TO great apes This also applies to a family of people with only one modern look reasonable man (Homo sapiens). According to archaeologists, the region of human origin appears to have been Africa. Morphologically, humans are characterized by exceptional development of the brain, weak development of the jaws and teeth, developed language and chin protuberance. The hairline is reduced, the spine is straightened, the skull is located on top of the spinal column, the legs end in an arched foot, the hand is a very perfect and universal organ. A person has articulate speech and is capable of very complex mental activity. The formation of Homo sapiens was associated with labor activity.

Table 21. Characteristics of the main orders of placental mammals
Squad	Number of species		Main features	Some representatives
	in the world	in the USSR
Insectivores	About 370	38	The teeth are of the same type, sharply tuberculate. The anterior end of the head is extended into a proboscis. The olfactory department is best developed in the brain, the hemispheres are almost without convolutions	Moles, hedgehogs, muskrats, brown-toothed and common shrews
Chiroptera	About 850	39	The forelimbs are transformed into wings. A keel is developed on the sternum; muscles that move the wings are attached to it. The auricles are large and complexly arranged; The auditory subcortical centers are very well developed. Many species navigate using ultrasonic echolocation	Long-eared bats, red-headed noctule, flying dogs, flying foxes, vampires
Rodents	2000	143	Strongly developed incisors have no roots and are constantly growing. There are no fangs. Molars have a large chewing surface covered with tubercles or ridges of enamel. Usually there is a large cecum	Squirrels, jerboas, beavers, marmots, muskrats, gophers, mice, hamsters, rats
Lagomorpha	About 60	12	They have two pairs of upper incisors, one of which is located behind the other	Hares, rabbits, pikas
Predatory	240	45	The incisors are small, the canines and carnassial teeth are highly developed - the last upper premolar and the first lower molar. In most species, the fingers are armed with sharp claws. Mainly Carnivores	Wolves, foxes, bears, arctic fox, sable, martens, raccoons, ermine, weasel, ferrets
Pinnipeds	30	12	Both pairs of limbs are transformed into flippers; there is a thick leathery membrane between the fingers. There is a thick layer of fat under the skin. Streamlined body, large	Walrus, seals, fur seal, seals, sea lion
Cetaceans	80	30	The forelimbs are transformed into flippers, the hind limbs are reduced. The body shape is torpedo-shaped. No hair, no ears. There is a caudal (in some species also a dorsal) fin. Orientation using sound echolocation	Dolphins, sperm whales, whales
Artiodactyls	170	24	The feet have four toes, of which the second and third are well developed. The toes have horny hooves. There are no collarbones. The stomach in most species is complex - from several sections	Pigs, elk, cows, deer, giraffes, antelopes, goats, sheep, bison, bison, yak, saiga, chamois, roe deer
Odd-toed ungulates	16	3	One (third) toe is well developed on the feet, usually with a hoof. There are no collarbones. Simple stomach	Zebras, tapirs, rhinoceroses, donkeys, horses
Proboscis	2	-	Very large animals. The nose and upper lip form a trunk. Paired upper incisors form tusks	Indian elephant, African elephant
Primates	About 190	-	Limbs of grasping type, five-fingered, thumb mobile and for many can be opposed to others. Nails are developed on the fingers. There are teeth of all categories. The brain has a large volume and complex structure; eyes are directed forward. When walking, rest on the entire foot	Tupai, lemurs, tarsiers, marmosets, howler monkeys, marmosets, macaques, baboons, orangutans, chimpanzees, gorillas

Economic and medical importance of mammals

It is difficult to name any group of animals that would have such significance in the history of mankind and in the economics of the national economy as mammals. He domesticated them first primitive man(he received from them food, raw materials for the production of clothing, shoes and draft power). Over time, hundreds of breeds of large and small ruminants, pigs, and horses have been developed, which are of great economic importance.

Currently, there are various breeds of cows (dairy - Kholmogory, Dutch, Yaroslavl; meat and dairy - Kostroma, Simmental; meat - Kalmyk, Shorthorn) and sheep (Romanov, Karakul, Askanian and Caucasian fine wool). One of the most important industries agriculture is pig farming. A particularly valuable breed is the Ukrainian Steppe white pig, bred by the Soviet livestock breeder M.F. Ivanov. There are many breeds of domestic horses, in particular Oryol trotters, Don, Arabian, English, Vladimir, etc.

Camels, buffalos, yaks, donkeys, and deer are also used in the national economy. In the northern regions of Russia, reindeer husbandry is an important branch of the economy; reindeer. Red deer are bred in park and hunting farms to produce antlers - non-ossified antlers containing pantocrine and other medicinal substances. Far Eastern sika deer and deer are bred for the same purpose. Deer and other wild ungulates also serve as a source of meat and skins.

Whales are important commercial species. They produce margarine, lubricants, glycerin, gelatin, glue, soap, cosmetics and medicines (in particular, vitamin A from the liver). Meat, entrails and bones are used to make feed meal for domestic animals, as well as fertilizers. Sperm whale spermaceti is a valuable product. Marine whaling is regulated by international agreements, but the number of whales and sperm whales is noticeably declining. Hunting of gray and blue whales, humpback and fin whales is currently prohibited International Convention. There is limited hunting for sperm whales, sei whales, bottlenose whales, and pilot whales. Pinnipeds are valuable objects of marine hunting. The skins of seals, harp and Caspian seals are used as fur raw materials (young animals), as well as for the needs of the leather industry. Fur is especially prized fur seals, which form large rookeries in Russia on the Komandorskie and Tyuleny Islands, and in the USA - on the Pribilof Islands. Fat and meat of pinnipeds are also used.

The USSR ranks first in the world in the production of fur-bearing animals. The bulk of the fishery consists of 20 species. The main commercial species of the forest zone remain sable, squirrel, marten, ermine, foxes and hares, and in the tundra - arctic fox and mountain hare, in the steppes and deserts - foxes, hares, gophers, in river valleys - muskrat, water rat, otter, nutria (in the south). About a third of the fur is mined in the north of our country. The hunting of valuable fur-bearing animals is carefully regulated and carried out on a scientific basis, which also includes the protection and breeding of animals. Especially great success achieved in increasing the sable population and in the artificial resettlement of beaver. The artificial relocation of sable to the forests of the Tien Shan, the Far Eastern raccoon dog and sika deer to the European part of Russia was also carried out. Some fur-bearing animals have been successfully acclimatized in our country, in particular the North American muskrat, South American nutria, and American mink.

Some species of mammals (rats, mice, guinea pigs, etc.) are used as laboratory animals in biological and medical research and are bred in large quantities.

Many wild mammals are reservoirs for pathogens of a number of vector-borne diseases. Gophers, marmots, tarbagans and other rodents are a source of human infection with plague and tularemia, mouse-like rodents and rats - with toxoplasmosis, epidemic typhus, plague, tularemia, trichinosis and other diseases.

Mammals are also of great importance as consumers of harmful insects (for example, insectivores - shrews, moles, hedgehogs; bats - long-eared bats, rufous noctule, etc.); some representatives of the order of carnivores - weasel, ermine, black polecat, pine marten, badger and others - feed on harmful rodents and insects. During the day, the weasel preys on 5-6 rodents, mainly red, gray and water voles; in summer it also feeds on click beetles. The badger feeds on mouse-like rodents and the larvae of beetles, click beetles, weevils, and leaf beetles.

Some mammals cause big losses national economy. Many species of rodents (mice, voles, gophers, rats) damage agricultural and forest crops, pastures, and stocks in storage facilities. Their harmfulness is increased by the fact that voles and mice are capable of mass reproduction. Marmots, gophers, gerbils, some voles, mice and other rodents can store and spread pathogens of dangerous diseases in humans and domestic animals (plague, tularemia, foot-and-mouth disease, etc.), their blood feeds on carriers of serious diseases - ticks, fleas, lice, mosquitoes, Some carnivorous mammals and bats harbor and transmit rabies pathogens. Many of these infections constantly exist in nature, that is, they have a natural focality. People and pets can become ill if they enter a natural outbreak and come into contact with sick animals or carriers. The theory of natural focality of diseases was developed by the outstanding Soviet zoologist Academician. E. N. Pavlovsky and his students. This theory became scientific basis organizing the fight against these diseases.

Pests of agriculture and forestry are most often exterminated with the help of pesticides, but their use has negative consequences - environmental poisoning, death of many beneficial animals, etc. Currently, in Russia, the bacterial drug Bactorodencid is being produced in a semi-industrial manner to combat rodents. The drug is added to baits made from grain, chopped potatoes, and bread crumbs.

Ferrets, foxes, and jackals can cause some harm to poultry farming, but natural conditions they often feed on mouse-like rodents, and some also feed on carrion, etc. Many valuable wild and domestic animals are destroyed by wolves; in some places it is necessary to limit their numbers, as well as the numbers of some other predators, by shooting.

Fur farming

Fur farming in our country arose about 200 years ago; in the USSR, this branch of livestock farming began to rapidly develop in 1928-1929, when the first specialized fur farming state farms were created to produce fur for export. Currently, fur farming is developing in three main directions: free, or island (this is how ungulates are bred mainly - deer, sika deer, elk, which produce antlers, skin and meat), semi-free (the main herd is kept in cages, young animals are kept in a limited area ) and cellular. The latter direction is the main form of modern industrial fur farming. Large fur farms contain up to 100 thousand animals, with 85-90% total number The main herd of females consists of mink of various colors. Nutria, foxes, arctic foxes, sables, chinchillas, and river beavers are also raised. As a result of the successful use of genetic breeding techniques, more than 30 types of colored minks, several types of colored foxes and blue foxes have been bred. In total, about 20 species of animals are bred in the world.

Mammal conservation

Over the past century on globe More than 100 species of mammals have been completely destroyed; currently, about 120 species of mammals are under threat of extinction. The problem of maintaining and increasing the number has become very important polar bear, tiger, snow leopard, bison, wild spotted deer, some species of whales and seals and other animals. For this purpose, the USSR adopted the Law “On the Protection and Use of Wildlife”, in accordance with which rare and endangered animal species are included in the Red Book of the USSR and the Red Books of the Union Republics. In our country, shooting and trapping of rare and endangered species of animals is prohibited; nature reserves, sanctuaries, and micro-reserves have been created where integral natural communities of animals are preserved.