The structure of the skull and the teeth of mammals The teeth of mammals have roots with which they are strengthened in the sockets of the jaws. They are differentiated. The incisors are used to capture prey and bite off, the fangs are used to hold, pierce and kill, the molars are used to tear if the edges of the teeth are sharp (predatory teeth), and crush and grind if the bumps are blunt or the tooth is folded.

The mechanism of respiration in mammals In mammals, costal breathing (as in reptiles) is supplemented by diaphragmatic breathing. The diaphragm is a muscular partition that separates the body cavity into the chest cavity, where the heart and lungs are located, from the abdominal cavity, the location of the rest of the internal organs.

The mammalian brain The large hemispheres of the forebrain are very strongly developed, mainly due to the growth and thickening of the cortex, which in higher mammals folds. Complex voluntary behavior, memory, and rational activity are associated with the mammalian cortex.

Classification of mammals Class Mammals Subclass Atheria Ateria Subclass Theria Viviparous Infraclass Primordial Beasts Infraclass Marsupials Infraclass Placentals Order Cloacous Order Marsupials Order Insectivores and others.

First animals, or oviparous Platypus near the water Platypus egg laying The platypus lives in Australia. This animal is the size of a rabbit. On the head it has a horny protrusion that looks like a duck's beak. He lays eggs and incubates them. The cubs feed on milk, which is secreted in the milky field of the female, located on the stomach.

marsupials Cubs in marsupials are born very small. The mother bears them for a long time in a bag on her stomach, where the cub crawls on its own along the wet path licked by the mother. The pouch contains the mammary glands with nipples. The newborn hangs on the nipple, not letting it out of his mouth.

Reproduction of placental mammals The placenta is a formation in higher mammals resulting from the fusion of two embryonic membranes - allantois and serosa. In the place of fusion of these two membranes, a spongy body is formed - the chorion, which forms villi that penetrate the epithelium of the uterus. The blood vessels of the child and maternal organisms are intertwined here, as a result of which gas exchange, its nutrition and the removal of decay products are ensured in the body of the embryo.

Order Insectivorous Shrew Desman The most primitive of modern mammals. Their body temperature is not always constant. The teeth are poorly differentiated, the brain is small, the hemispheres of the forebrain are without convolutions, the muzzle is with an elongated proboscis.

Chiropteran order Capable of long-term active flight With the help of the forelimbs, which have turned into wings, which are formed by a leathery membrane stretched between the fore and hind limbs and the tail. A keel is developed on the sternum. Horseshoe bat Most bats are small insectivorous animals. They lead a nocturnal lifestyle. They have the ability to echolocate. Some of them feed on juicy fruits, others on insects, and others on fish. AT South America live the bats- vampires.

Order Rodents The largest order of mammals, numbering about 2000 species, including terrestrial, arboreal, semi-aquatic and underground animals. Flying squirrel Self-sharpening incisors are well developed (1 pair of upper and 1 pair of lower ones), fangs are absent, molars have a flat surface. Rodents have a long intestine with a highly developed caecum. Capybara or capybara - the largest rodent

Order Predatory digitigrade predatory mammals, leading mainly a terrestrial way of life. They have large fangs (incisors are small). Among the molars, 4 carnivorous teeth stand out in size. The intestine is short. Clavicles are absent. The brain is well developed, many convolutions.

Family Canine Fox Raccoon dog Predators adapted to procuring prey by stalking. They have long jaws that help them grasp and kill their prey with their teeth. Thin, capable of fast and long running legs, non-retractable claws, long fluffy tail. Very attentive and smart.

Family Cheetah Cats Predators of large and medium sizes, Most often lying in wait for their prey. They have retractable claws. Cats Use their teeth not to capture the victim, but mainly to kill it, therefore they have shortened jaws, but large teeth. The exception is the cheetah. Lynx

Mustelidae family Mostly mustelids are predators of small sizes with a long and narrow flexible body on low legs. They hunt rodents and birds. Ermine in summer and winter dress Ferret

Bear family Large animals of a massive build with a large head, an elongated muzzle and powerful five-fingered plantigrade limbs. There are 3 types of bears in our country: brown, white and white-breasted (Himalayan).

Squad Pinnipeds Large animals with a spindle-shaped body, a short neck and limbs turned into flippers. Most of the time is spent in the water. They come ashore for breeding and short rest Northern fur seal Walrus

Order Cetaceans Aquatic mammals that never come to land. They swim with the help of a tail fin and a pair of forelimbs modified into flippers. Hind limbs are absent.

Baleen whales Instead of teeth, baleen whales have a baleen - numerous elastic horny plates with fringed edges hanging from the upper jaw. They feed on small aquatic animals.

Toothed whales Have numerous identical cone-shaped teeth (some have up to 240 pieces), which serve only to capture prey.

Detachment Odd-toed ungulates Tarpan lived in the steppes of the Black Sea region. Exterminated in the 19th century. Rhinoceros with a calf Mostly odd-toed ungulates are inhabitants of open spaces, adapted to fast running. They have a well-developed third finger, the end of which is covered with a horny hoof. The remaining fingers are absent or poorly developed. Odd-toed ungulates are herbivores. They have a single chamber stomach and a highly developed caecum.

Order Artiodactyls. Ruminant artiodactyls cut grass, leaves, shoots and branches with incisors of the lower jaw and grind with molars. First, food that is lightly chewed and abundantly moistened with saliva is swallowed and enters the rumen, where, under the influence of unicellular symbionts, it undergoes fermentation. And gradually moves to the second section of the stomach - a mesh with cellular walls. From here, it burps into the mouth, mixes for a long time and thoroughly and is swallowed into a book - a section of the stomach with high folds on the walls. After that, the food slurry passes into the last section of the stomach - the abomasum, where it is exposed to the action of gastric juice.

Order Artiodactyls. Non-ruminant Animals with a large massive body, small legs, a short neck and a small tail. The stomach is unicameral. Boar Hippo in cub

The Primate order Tupaya is the most primitive primate. These are small animals that look like a rat and a squirrel at the same time. Spider Monkey - typical representative broad-nosed monkeys from the New World.

Importance of mammals l l l l Regulate the growth and development of plants. Promote the spread of fruits and seeds and the resettlement of plants. Limit the number of other animals (invertebrates, rodents, etc.) Serve as food for (birds, reptiles, mammals). Enrich the soil with organic matter. They are a source of meat and milk for humans, furs, skins and other raw materials for industry. Serve as vehicle. Destroy pests of agriculture and forestry. Destroy sick and weakened animals. They are pests of agriculture, spoil food. Destroy pets. They are carriers of human pathogens. They have aesthetic value. They are of scientific importance.

Mammal body it is subdivided into the head, neck, trunk, tail (in some representatives it is absent) and two pairs of five-fingered limbs (in cetaceans, the hind pair of legs atrophies).

The body has a hairline that protects the skin from mechanical damage, moisture and plays an important role in maintaining constant temperature body. Like all vertebrates, the skin is two-layered, rather thick and durable. Its outer layer - the epidermis - gives a number of derivatives: hair and all their varieties (vibrissae - "whiskers" in cats, bristles in a pig, needles in a hedgehog and porcupine), horny plates (armadillos), horns (rhinos, deer), claws (predators), nails (humans and primates), hooves (horses, cows, hippos). Under the epidermis is the skin itself (dermis), and under it is a layer of subcutaneous fatty tissue. The skin contains sebaceous, sweat, milk and odorous glands. The milk and odorous glands are modified sweat glands.

The axial skeleton, like that of reptiles, has 5 sections: cervical (in most cases 7 vertebrae), thoracic (from 9 to 24 vertebrae), lumbar (2-9 vertebrae), sacral (4-9 vertebrae), caudal (from 3 up to 49 vertebrae). The thoracic vertebrae articulate with the ribs. The neck of mammals is more mobile than that of reptiles, and less mobile than that of birds. Its length is different different types(e.g. mouse and camel). All mammals have a well-developed bony palate. The skull is characterized large sizes brain department and the tendency to accretion of bones. The dental system of mammals reaches perfection. The structure of the limbs is typical for terrestrial vertebrates. The development of the phalanges of the fingers depends on the lifestyle of the animal: in fast-running ones, their number is reduced (artiodactyls and equids); the structure of the hand in burrowing animals (mole) is peculiar; elongated phalanges of the fingers and leathery membranes between them are found in animals with gliding flight (flying squirrel, bats). The belt of the forelimbs is made up of the shoulder blades and collarbones. In most species, the clavicles are well developed. In ungulates and cetaceans, they are absent, which is associated with the monotonous movements of their limbs. The pelvis is well developed. Its bones in adult animals grow together.

The muscular system is more developed and complicated compared to reptiles. Particularly developed muscles associated with the limbs, numerous flexors and extensors. Degree of development muscular system depends on the lifestyle of the animal.

Digestive system characterized by differentiation of teeth (incisors, canines and molars) and parts of the digestive tube, which is directly dependent on the lifestyle and nature of food (carnivorous, herbivorous, omnivorous). For example, with monotonous food in insectivores, the teeth are poorly differentiated, incisors are developed in rodents and fangs are absent, in carnivorous mammals, fangs are strongly developed. Characterized by the change of milk teeth to permanent ones. The mouth opening is surrounded by fleshy lips. In the oral cavity, mechanical and chemical processing of food begins (enzymes of the salivary glands). The structure of the stomach also depends on the nature of nutrition. In most mammals, the stomach is divided into sections. The stomach of ruminants is the most complex. In cows, it has 4 sections: abomasum, book, mesh and scar. The intestine consists of the small, large, and rectum and ends at the anus. Between the small and large intestines is the caecum with a appendix. Digestive glands are well developed: salivary glands, glands of the stomach and small intestine, liver and pancreas.

Significantly more complicated than reptiles excretory system. Excretory organs are paired pelvic kidneys. They increased the number of vascular glomeruli and there was a significant elongation of the renal tubules. Urine passes through the ureters to the bladder, which opens to the outside with an independent opening. Part of the dissimilation products is excreted with sweat through the skin.

The circulatory system has two circles of blood circulation. The heart is four-chambered. Arterial and venous blood are completely separated. Unlike birds, mammals have a functioning left aortic arch. Thanks to intensive metabolic processes and a perfect thermoregulation system, mammals maintain a constant and heat bodies: they are homoiothermic animals.

Compared to reptiles, the respiratory system is much more complicated. Respiratory organs - lungs. They have an alveolar structure, which greatly increases their respiratory surface. The role of the skin in gas exchange is insignificant. Air enters through the nostrils into the nasal cavity, which has a complex structure, then passes through the larynx, trachea and bronchi. The branching bronchi form the bronchial tree in the lungs. At the ends of the smallest bronchi, alveoli are formed - vesicles consisting of a single layer of epithelial cells, densely braided with blood capillaries, in which gas exchange occurs. Due to the development of the hard and soft palate, the airways are separated from the oral cavity. Respiratory movements are provided by changes in the volume of the chest, in which the intercostal muscles and the diaphragm are involved - the muscular partition between the chest and abdominal cavities.

The complex behavior of mammals, which is based on instincts, provides an improved brain and sensory organs. The cerebral cortex of the forebrain has furrows and convolutions. The cortex becomes the highest department of the central nervous system, coordinating the work of other parts of the brain and the whole organism. In front of the cerebral hemispheres are large olfactory lobes. The midbrain is small and is distinguished by the presence of the quadrigemina (the anterior lobes are visual, the posterior lobes are auditory). The cerebellum is well developed, which regulates coordination of movements, balance and muscle tone.

The most important sense organ in mammals is the sense of smell (search for food, individuals of their own species, identification of enemies). The organ of hearing is represented by three departments: the inner ear (the cochlea and the organ of Corti), the middle ear (the tympanic membrane and three auditory bones - the hammer, anvil and stirrup) and the outer ear (the external auditory canal and auricle). Vision in the life of mammals is less important than for birds. Its severity depends on the living conditions and varies greatly among animals in open spaces (antelope) and underground (mole). Some mammals (horses, cats, monkeys) have developed color vision. The function of the organs of touch is performed by the hairline. Particularly sensitive are long coarse hairs - vibrissae located on the cheeks, lips, chin and eyebrows. Taste organs are also developed. Some animals (dolphins, bats) are characterized by echolocation (orientation in space using ultrasonic signals). Due to the presence of sensory organs, the animal receives information about changes in the environment.

Mammals have complex behaviors. Its features are determined by the lifestyle of the animal. So, a predator tracks down prey, lies in wait for it, kills it, eats it itself, and if there are cubs, it takes it to them. Accordingly, the prey animal behaves in such a way as to avoid meeting with a predator (camouflage coat color, entanglement of traces).

Everyone has mammals developed care for offspring. Usually, before the birth of the cubs, the female builds a nest for herself. In addition to feeding, she monitors the cleanliness of the cubs, warms them with her body, and protects them from enemies. After the cubs begin to see clearly, their parents teach them how to behave in the environment, how to get food and defend themselves from enemies. The most complex instincts for caring for offspring are observed in primates.

Mammals are dioecious. Insemination is internal. An insignificant part of the animals lays eggs (platypus, echidna), but they feed the young from the eggs with milk. In most mammals, the development of the embryo occurs in utero (in the uterus). Its nutrition and gas exchange is provided by a special organ - the placenta (children's place). All representatives of the class feed their young with milk.

Class taxonomy
The Mammals class combines two subclasses.

1. First beasts, or cesspools (echidna, platypus). These are the oldest mammals (live in Australia), which have common features with reptiles (Fig. 55). The rectum, ureters, and genital ducts empty into the cloaca. They have unstable body temperature (from +26 to +34°C). The first animals lay eggs, but the young are fed with milk. Their mammary glands do not have nipples and open with numerous holes in a special glandular field (milky field).

2. Placental, or real animals. They appeared later than other animals. They are characterized by a long intrauterine development, during which the embryo is connected with the mother by a special formation - the placenta.

Subclass Placentals is subdivided into 17 orders. The most common are the following groups.

Marsupials (kangaroo, marsupial wolf, mole, squirrel). At present, marsupials have survived only in Australia. Their cubs develop in utero, but are born underdeveloped, since the placenta in marsupials does not form. After birth, they are in a special bag on the ventral side of the body of the female. The mammary glands open into the pouch. The edges of the cub's mouth grow together with the nipples, so it does not fall out of the bag. Most marsupials are herbivores, some are carnivores or insectivores. Man uses the meat and fur of some marsupials.

Bats (bats, fruit bats, flying dogs). This is a peculiar group of mammals leading an aerial lifestyle. Their bones are thin and light, the sternum has a keel. The wings (modified forelimbs) are formed by leathery membranes that are stretched between the fingers, as well as between the fore and hind limbs and the tail. Bats are nocturnal. They navigate in flight by means of echolocation. They have large ears. American vampires attack large mammals at night, cut off pieces of skin with their incisors and lick the blood. Herbivorous flying dogs feed on fruit and damage horticulture. Many eat insects. During the day, bats sleep, hanging upside down in the hollows of trees, in basements, in attics. With the onset of cold weather, they hibernate.

Rodents (mice, rats, ground squirrels, muskrats, beavers, squirrels, hares, etc.). The richest group in representatives. Animals are small or medium in size. They live in a variety of conditions - on trees, in water, underground (in burrows). They eat plant foods. Characteristics teeth: incisors do not have roots and grow throughout life (animals must gnaw something to grind them down); no fangs; molars have a wide surface for grinding food. The intestine is long, with a strongly developed caecum. Important biological feature rodents - high fertility. Most of them quickly reach sexual maturity, have a short period of intrauterine development (20-21 days) and give up to 10 cubs several times a year. Mouse-like rodents cause great economic damage as pests of agricultural crops. They can be a source of a number of dangerous human diseases (rabies, plague, various fevers, encephalitis). Rodents serve as food for reptiles, birds, predatory mammals. Some of their species are the object of trade due to their valuable fur (beaver, squirrel, muskrat).

Predatory (bear, marten, ermine, cat, dog, etc.). Large animals, mostly carnivores, but there are also omnivores. First, they kill the victim, and then tear it apart with their teeth. Their incisors are poorly developed, fangs and carnivorous teeth are most pronounced. The molars have a tuberculate surface. The limbs are equipped with well-developed claws; in cats, the claws are retractable. Predators are varied appearance, behavior, therefore they are divided into a number of families: bear (brown, white, Himalayan bear), marten (marten, weasel, sable, ermine), feline (domestic and wild cats, lynx, tiger), canine (dog, wolf, fox). Dogs overtake prey with a rut. Felines more often lie in wait for the victim from an ambush, rush at her with a jump and kill her. Predators cause significant damage to livestock. AT natural conditions they are the regulators of the number of those animals that serve them as food, exterminate harmful rodents. Foxes in large numbers destroy mouse-like rodents. Cats and dogs are experimental animals in biological and medical research. At the same time, they pose a danger to humans, as they infect him with rabies, toxoplasmosis, and echinococcosis. Cats and dogs are of aesthetic importance, many decorative breeds of these animals have been bred (about 350 breeds of dogs). Thanks to valuable fur, many predatory animals (marten, sable, ermine, fox, lynx, otter, etc.) are the object of hunting or are bred in special fur farms.

Pinnipeds (walruses, seals, fur seals). Large animals, inhabitants of the cold polar seas, often gregarious. They are adapted to life in water and move poorly on land. They have a streamlined body shape, limbs transformed into flippers, a thick layer subcutaneous fat. Their body is covered with short thick hair without undercoat. The auricles are absent. The eyes are large, the lens is spherical (for vision in water). The structure of the teeth, like those of predatory animals. They eat fish sea ​​shellfish. For breeding and rearing the young, they come to land. All pinnipeds are the object of fishing - they use their fur (seal), fat and skin.

Cetaceans (whales, sperm whales, dolphins). The representative of this detachment is the blue whale, the largest of all animals (its body length is up to 33 m, weight is up to 120 tons). Cetaceans live only in water and do not go out on land. Their body is fish-shaped, without hair. The head is very large. The neck is unexpressed. The hind limbs are reduced, only the remains of the pelvis are preserved; the front ones are modified into flippers. The main function of movement is performed by the tail. The subcutaneous layer of fat is well developed (in some whales up to 50 cm). The auricles are absent. The organ of hearing is greatly reduced. The eyes have a flat cornea and a spherical lens - adaptations for vision in water. Lacrimal glands and lacrimal canal are absent. The brain has a complex structure. Dolphins are highly trainable. The teeth are either identical or missing. Toothed cetaceans (dolphins, sperm whales) feed on fish, swallowing it whole. Toothless cetaceans (whales) eat small animals, mainly crustaceans, filtering water through the "whalebone" (elastic horny plates up to 5 m long with fringed edges located on the upper jaw). Cetaceans are an important fishery object. Fat, whalebone and skin are used. Feed flour is prepared from meat. From the head of sperm whales, a waxy substance, spermaceti, is extracted, which is used in the medical and perfume industries.

Artiodactyls (hippos, pigs, giraffes, antelopes, horned livestock, etc.). Mostly large herbivores. They have a characteristic structure of the limbs: the first toe is absent, the second and fifth are underdeveloped, the third and fourth are covered with a horny sheath called a hoof. Clavicles are absent.

The first group - non-ruminant artiodactyls - is represented by hippos and pigs. There are no horns. Legs are short. The skin is bare or covered with bristles (strong awn). The subcutaneous fat layer is well developed. The stomach is simple. They feed on rhizomes, tubers, fruits, they can eat earthworms, mollusks, mouse-like rodents. The molars have a tuberous surface for grinding food. The wild boar uses its sharp fangs protruding outward to loosen the soil in search of food and to protect itself from enemies. The wild boar gave rise to many valuable breeds of domestic pigs. The most famous is the white Ukrainian breed, bred by M.F. Ivanov.

The second group of artiodactyls is ruminants (camels, deer, giraffes, antelopes, large and small cattle). The skin is covered with thick hair. The subcutaneous fat layer is not developed. Many of them have horns that serve as protection from enemies. The second and fifth fingers are rudimentary. The stomach of ruminants consists of 4 sections - scar, mesh, book and abomasum. Well developed molars. The incisors and fangs of the lower jaw (they are not on the upper jaw) and the tongue help the animal to pluck the grass, which is almost not chewed and enters the rumen, where it is partially decomposed by bacteria and protozoa. Then the food passes into the grid, where large masses of it accumulate while the animal is on the pasture. At rest, during rest, food is burped from the scar and mesh in small portions into oral cavity, chewed thoroughly and for a long time, after which it is swallowed again and falls into the book. In the book, the mechanical processing of food ends, and in the abomasum, under the action of enzymes, digestion occurs. The intestine is very long. The caecum is well developed. Many ruminants are domesticated and are represented by a number of valuable breeds. A person uses artiodactyls for food (meat, milk), as a raw material for industry (wool, leather), for medicines (deer antlers, endocrine glands of cattle, blood serum), as a draft force (oxen, deer , camels).

Odd-toed ungulates (tapirs, rhinos, horses, zebras, donkeys). Large herbivores. They have developed mainly the third finger of the limbs, the rest are reduced. Clavicles are absent. The most progressive group is the horse family. Przewalski's wild horse is an inhabitant of open steppe spaces. Her coat is short, yellowish-gray. It feeds on dry plants of the steppes and semi-deserts. With large incisors, the horse bites plants, with large mobile lips it holds them in the mouth, grinding them with molars. Food processing ends in the caecum. Many breeds of horses have been bred by man: the Oryol trotter, Arabian horses, Akhal-Teke horses, heavy trucks, etc. Domestic horses are used in the economy as a draft force; their meat is eaten; from the milk of mares prepare a medicinal drink koumiss.

Primates, or monkeys (monkeys, gibbons, great apes). Arboreal or terrestrial animals, of medium or small size. Representatives of the detachment are characterized by a herd way of life. Almost everyone is active in daytime. Their toes have nails. Most primates live in trees, and therefore the thumb of the front and hind limbs is opposed to the rest. The presence of clavicles in the shoulder girdle provides complex movements of the limbs. Diet varied but preferred by primates juicy fruits. All types of teeth are developed. Binocular vision (eye sockets directed forward), stereoscopic, color. The cerebral cortex has the most complex structure. Female primates have a pair of mammary nipples. The babies are born helpless. In the detachment, broad-nosed monkeys (marmosets, capuchins) and narrow-nosed monkeys (monkeys, chimpanzees, gorillas, orangutans) are distinguished. Monkeys are usually used as experimental animals to study conditioned reflexes, higher nervous activity, and behavior. This group also includes humans.

Origin of mammals

The ancestors of mammals were animal lizards. The first mammals appeared at the beginning mesozoic era and were small animals the size of a rat. They possessed a number of progressive features that provided them with dominance in the animal world from the beginning of the Cenozoic era.

The value of mammals

In nature, mammals actively participate in the circulation of substances, distribute the fruits and seeds of plants. In human life, they serve as a vehicle, provide raw materials for obtaining medicines; their fur and skin are also used. Mammals, especially domestic animals, provide valuable food. They are. serve as experimental animals, have great aesthetic value. Economic damage to the economy is caused by mouse-like rodents, as well as predators that destroy domestic animals. Mammals can be a source of pathogens for a number of dangerous human diseases.

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

• hairline
• skin glands
• warm-bloodedness
• constant body temperature
• developed cerebral cortex
• live birth
• care of offspring
• complex behavior.

All this allowed mammals to win 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.

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

A highly developed nervous system allows mammals to better adapt to conditions environment and make fuller use of natural resources in the extraction of food, in protection from enemies, in the construction of holes, shelters.

The transfer of experience, the training of young animals, and the foresight of 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 living alone or in families in a permanent place, others roam in a herd or flock. Plays a big role a complex system subordination, when there is a selection for the best organization of the herd or pack.

In food chains, mammals also occupy different positions: some are primary consumers of plant foods (consumers of the 1st order), others are carnivorous, peaceful (insect- and plankton-eating - consumers of the 2nd order), and others are predatory (attacking large active prey - consumers of the 2nd and III order). Mixed nutrition is characteristic of primates, predators and rodents. The relationship of animals with plants is very close, which, on the one hand, are an object of eating (in this case, fruits and seeds often spread), and on the other hand, they protect themselves from them with the help of thorns, thorns, an unpleasant smell, and a bitter taste.

Of the entire animal world, man is more closely associated with 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 at the present time: new breeds are bred and old ones are improved by hybridization with wild animals.

An important role in the human economy is played by hunting and sea fishing, acclimatization of animals from other continents.

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 human economy, they study the structure of their populations, population dynamics, food resources - all these data are 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 her harmfulness.

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

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

In the modern fauna there are 4000-4500 species of mammals, including within Russia - 359 species, in Ukraine - 101. Mammals are common 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. In connection with adaptation to life in different conditions, the external appearance of these animals is very different, but they differ sharply from all other features of the internal and external structure.

Class characteristic

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

Thanks to the progressive development of the central nervous system, warm-bloodedness, the presence of hair, bearing cubs 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.

body integuments. Like all vertebrates, mammalian skin consists of a multi-layered epidermis and corium. Outside, the body is covered with the epidermis, the upper stratum corneum in the form of separate dead cells constantly disappears. The renewal of the epidermis occurs due to cell division of the Malpighian layer. The corium is built 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 of mammals. In most animals, the hairline is developed on the entire surface of the body (absent on the lips, in some - on the soles). Mammalian hair is heterogeneous. Large, long, stiff, protruding hairs are called vibrissae, they are located at the end of the muzzle, belly, limbs, serve as organs of touch, their bases are connected with nerve endings.

The hair consists of a trunk and a root. The trunk is built of a heart-shaped substance, covered with a cortical layer and outside with a skin. There is air in the cavity of the hair. The hair root ends with a bulb, at the base of which the hair papilla enters. It is rich in blood vessels and serves to nourish the hair. The hair papilla is located in the hair bag, 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 secrete sweat, due to which thermoregulation is carried out. In temperate and northern latitudes, most species change their hairline 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 body temperature largely depends on temperature external environment and fluctuates between 25-36 °C. Perfect thermoregulation of most mammals is ensured by the presence of sweat glands, hairline, fatty subcutaneous tissue, and breathing also takes part in thermoregulation.

Skeleton. The skeleton consists of a skull, spine, limb girdles, and bones of paired limbs. The skull of mammals is characterized by a large volume of the cranial, or brain, box. Its bones grow together at the seams quite late, therefore, during the growth of the animal, 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 bones of the jaw became the auditory ossicles, the hammer and anvil. Thus, mammals have three auditory ossicles - the stirrup, hammer and anvil, while amphibians, reptiles and birds have only one - the stirrup (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. A constant number of cervical vertebrae (7) is characteristic. On the front side of one of the two cervical vertebrae - the atlas - there are two articular surfaces, like in amphibians. To the vertebrae thoracic the ribs are articulated, with their cartilaginous part they are connected to the sternum, or sternum, forming the chest. The sacral vertebrae fuse together and are connected to the bones of the pelvic girdle. The number of tail vertebrae ranges from 3 (in the gibbon) to 49 (in the long-tailed pangolin). The degree of mobility of individual vertebrae is different. The most mobile vertebrae are 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 cartilaginous discs (menisci) located between the vertebrae.

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

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

Muscular system. In mammals, it is exceptionally developed, complex and has several hundred individual specialized muscles. Chewing and mimic muscles, especially in monkeys and humans, as well as subcutaneous muscles, reach high development. A typical muscular formation of mammals is the abdominal obstruction, or diaphragm (the muscular septum separating the chest cavity from the abdominal cavity). The diaphragm plays a big role in breathing. When lowering and raising the diaphragm, the volume of the chest changes and intensive ventilation of the lungs is carried out.

Digestive system. The digestive organs begin with a 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 off and grinding food, capturing and killing prey, etc. The structure of the teeth is associated with the lifestyle of the animal. The tooth consists of 1-2 roots and a crown. Teeth are built from dentine, cementum and enamel, located in the sockets of the jaw bones. The echidna, anteater, and some cetaceans have no teeth. During the development of the animal, two changes of teeth occur - milk and permanent.

At the bottom of the mouth is the tongue, it 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 salivary glands open into the oral cavity. Saliva not only moisturizes food - it contains enzymes that break down starch into glucose during chewing. Thus, food processing begins already in the oral cavity.

Further, food enters the pharynx, esophagus, and from it into the stomach. The structure of the stomach, consisting of cardiac and pyloric sections, is diverse, which is associated with the nature of 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 process of digestion continues. The stomach of ruminant ungulates, which eat a large number of indigestible rough vegetable 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 is completed and the absorption of essential nutrients occurs. On the border between the small and large intestines in some mammals is the caecum and appendix. Undigested food remains enter the large intestine and are expelled through the rectum.

Respiratory system. The respiratory organs in 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, 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 the surface of the body. Contractions of the diaphragm and intercostal muscles increase the volume of the chest cavity, air is pumped into the lungs, and inhalation occurs. When the muscles relax, the volume of the chest cavity decreases, exhalation occurs.

excretory system. The excretory organs are characterized by the fact that the bladder does not open 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 is close to circulatory system 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 the formed state are devoid of nuclei.

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

The level of development of the sense organs depends on the way of life of animals and obtaining food. For the inhabitants of open spaces, vision is of paramount importance, for nocturnal and twilight animals, inhabitants of forests and thickets of shrubs, reservoirs 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 turbinates 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 sharpness of the sense of smell. Taste organs are taste buds in the mucous membrane of the mouth and tongue.

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

In the auditory region, a spirally twisted cochlea is very developed with several thousand of the finest fibers that resonate when sound is perceived. The vestibular region 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 cochlea allows mammals to distinguish the highest frequencies.

The eye of mammals is covered with a fibrous tissue - the sclera, which in front passes 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, regulates the illumination of the retina by changing the size of the pupil. The lens has a lenticular shape, it is enlarged in nocturnal and crepuscular animals. Accommodation is achieved only as a result of a change in the shape of the lens. The retina is adjacent to the inner side of the choroid - 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, distinguish four colors. Vision is well developed in nocturnal animals, in particular, cats distinguish six primary colors and 25 shades. gray color. 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 the intrauterine development of the embryo occurs. In most mammals, during the development of the embryo, the placenta is formed in the uterus, gas exchange occurs through it, the embryo is nourished and the metabolic products are excreted. At oviparous mammals the placenta is absent, in marsupials it is rudimentary. The vast majority of mammals are characterized by live birth, and only oviparous ones lay large, yolk-rich eggs. All mammals feed their young with milk. They differ a high degree care for offspring. Most mammals build special nests, even after milk feeding is completed, they take care of their young for a long time and diligently, train them.

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

Table 20. The division of mammals according to the characteristics of reproduction and organization
Subclass	Number of species)	Spreading	Characteristic features	Lifestyle
Oviparous or cloacal	4 (platypus and 3 species of echidnas)	Australia, islands New Guinea and Tasmania	Primitive: in the shoulder girdle there are coracoids; there is a cloaca; lay eggs. Progressive: hairline, 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 dependent on the ambient temperature	The platypus lives along the banks of water bodies, swims and dives well, feeds on aquatic invertebrates (insects, crustaceans, mollusks, worms). The cubs have milk teeth, in adults the jaws are toothless, flat. The paws have webs and claws. Eggs with a diameter of 15-20 mm, in a parchment-like shell, lay in a hole, incubate for 7-10 days
marsupials	About 250	Australia, New Guinea, etc.; South and North America	Primitive: the placenta is underdeveloped, the gestation period is very short, the presence of a bag on the stomach is characteristic, in which the development of the cubs ends. Progressive: live birth; mammary glands with nipples, coracoids fuse with shoulder blades. Body temperature around 36°C. Teeth are not interchangeable (corresponding to the milk teeth of higher mammals)	There are insectivores (marsupial mice, moles), carnivores (marsupials, martens), herbivores (kangaroos, marsupial bear- koala)
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 fuse with the epithelium of the uterus; give birth to well-formed cubs capable of feeding on mother's milk on their own. Have milk and permanent teeth	There are insectivores, carnivores, herbivores; 17 orders in total (the main ones are insectivores, bats, rodents, hares, carnivores, pinnipeds, cetaceans, artiodactyls, equids, proboscis, primates)

Monotremes, or cloacals (platypus, echidna, prochidna), live only in Australia. They lay rather large eggs with a lot of nutrients. After fertilization, the egg stays in the mother's genital tract for a long time (16-27 days), at which time the embryo develops in it. The period of incubation or carrying the egg is short and does not exceed 10 days. Monotremes lack teeth. The intestines and urogenital 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. Paired oviducts (fallopian tubes) and the uterus pass into the urogenital sinus. The listed features indicate a significant primitiveness of the structure of cesspools and their proximity to ancestors common with reptiles.

Lower animals, or marsupials (kangaroo, marsupial wolf, marsupial mole, 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 bag, hanging on the nipple (for example, a giant kangaroo weighing 60-70 kg gives birth to a cub weighing only 80 g the size of a walnut, other marsupials have even smaller newborns). Newborn marsupials independently crawl into the mother's pouch, where they find the nipple. As soon as the cub finds the nipple, the latter swells and fills the oral cavity of the newborn. The calf feeds on milk and lives in the mother's pouch from 60 days in small species to 250 days in large species. The brain of marsupials is primitive. There are two uteruses and two vaginas. Teeth, except for the front molar, are not replaced. Body temperature is not strictly constant, but higher than that of single passers.

The vast majority of modern mammals belong to the higher animals, or placentals. Their features are that the nutrition of the embryo occurs through the placenta. The cub is born more or less developed and can suck milk. The brain is well developed. There are two changes of teeth.

Modern placental are divided into 16 orders. The most important of them are: insectivores, bats, edentulous, rodents, carnivores, pinnipeds, cetaceans, ungulates, proboscis, primates. The order of insectivores, very ancient in origin, is distinguished by the greatest primitiveness of the structure. One of the most highly organized orders (although retaining many primitive structural features) are primates. Characteristic features of the main orders of mammals are given in table. 21.

There are suborders of lower primates, or semi-monkeys (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 anthropoid (orangutans, chimpanzees, gorillas) monkeys are distinguished. All groups of modern primates are characterized by a high level of specialization.

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

The higher primates also include the family of people with the only modern species of Homo sapiens. According to archaeologists, the region of human origin, apparently, was Africa. Morphologically, a person is characterized by an exceptional development of the brain, a weak development of the jaws and teeth, a strongly developed tongue and a chin protrusion. The hairline is reduced, the spine is straightened, the skull is on the spinal column from above, the legs end arched foot, the hand is a very perfect and versatile organ. A person owns 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
Detachment	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 region is best developed in the brain, the hemispheres are almost without convolutions	Moles, hedgehogs, desmans, brown-toothed and common shrews
Bats	About 850	39	The forelegs are modified into wings. The keel is developed on the sternum, the muscles that move the wings are attached to it. The auricles are large, complex; the auditory subcortical centers are very well developed. Many species navigate using ultrasonic echolocation	Earflaps, red evening, flying dogs, flying foxes, vampires
rodents	2000	143	Strongly developed incisors do not have roots and constantly grow. There are no fangs. The molars have a large chewing surface covered with tubercles or ridges of enamel. There is usually a large caecum	Squirrels, jerboas, beavers, marmots, muskrats, ground squirrels, mice, hamsters, rats
Lagomorphs	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 fangs and carnassials are strongly developed - the last upper premolar and the first lower molar. In most species, the fingers are armed with sharp claws. Predominantly Carnivores	Wolves, foxes, bears, arctic fox, sable, martens, raccoons, ermine, weasel, ferrets
pinnipeds	30	12	Both pairs of limbs are transformed into flippers, a thick leathery membrane is 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 hairline, ears. There is a caudal (in some species and dorsal) fin. Navigate with sound echolocation	Dolphins, sperm whales, whales
artiodactyls	170	24	There are four toes on the feet, of which the second and third are well developed. On the fingers - horny hooves. There are no keys. The stomach in most species is complex - from several departments	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 keys. simple stomach	Zebras, tapirs, rhinos, donkeys, horses
proboscis	2	-	Very large animals. nose and upper lip form a trunk. Paired upper incisors form tusks	Indian elephant, African elephant
Primates	About 190	-	Limbs of a grasping type, five-fingered, the thumb is mobile and in many can be opposed to the rest. 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, they rely on the entire foot	Tupai, lemurs, tarsiers, marmosets, howler monkeys, monkeys, 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 economy of the national economy as mammals. They were first domesticated by 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 cattle, pigs, horses were bred, 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, Askani and Caucasian fine-fleeced). One of the most important branches of agriculture is pig breeding. Especially valuable breed- steppe Ukrainian 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, buffaloes, yaks, donkeys, and deer are also used in the national economy. In the northern regions of Russia, reindeer breeding is an important branch of the economy; reindeer have long been domesticated there. Red deer are bred in park and hunting farms to obtain antlers - non-ossified horns containing pantocrine and other medicinal substances. For the same purpose, Far Eastern spotted deer and marals are bred. Deer and other wild ungulates are also a source of meat and skins.

Whales are important fish species. They produce margarine, lubricants, glycerin, gelatin, glue, soap, cosmetics and drugs (in particular, vitamin A from the liver). Meat, entrails and bones are used to make feed flour for pets, as well as fertilizers. A valuable product is sperm whale spermaceti. Marine whaling regulated international agreements, however, the number of whales and sperm whales is noticeably declining. Hunting for gray and blue whales, humpback whales and fin whales is currently prohibited. international convention. There is limited hunting for sperm whales, sei whales, bottlenose whales, pilot whales. Valuable objects of marine hunting are pinnipeds. Skins, 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 Tyuleniy Islands, in the USA - on the Pribylov 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 is made up of 20 species. The main commercial species of the forest zone are sable, squirrel, marten, ermine, foxes and hares, and the tundra - arctic fox and white hare, in the steppes and deserts - foxes, hares, ground squirrels, in river valleys - muskrat, water rat, otter, coypu (on South). About a third of furs are mined in the north of our country. Hunting for valuable fur animals is carefully regulated and carried out on a scientific basis, which also provides for the protection and breeding of animals. Particularly great successes have been achieved in increasing the number of sables and in the artificial resettlement of the beaver. The artificial resettlement of the sable to the forests of the Tien Shan, the Far Eastern raccoon dog and spotted deer to the European part of Russia has also been carried out. Some fur-bearing animals have been successfully acclimatized in our country, in particular, the North American muskrat, the South American nutria, and the 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 numbers.

Many wild mammals are reservoirs for a number of vector-borne diseases. Ground squirrels, 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 also have great importance as consumers of harmful insects (for example, insectivores - shrews, moles, hedgehogs; bats - ears, red evening, etc.); some representatives of the predatory order - weasel, ermine, black polecat, pine marten, badger and others - feed on harmful rodents and insects. During the day, weasel gets 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 larvae of beetles, click beetles, weevils, and leaf beetles.

Some mammals cause great losses national economy. Many species of rodents (mice, voles, ground squirrels, rats) damage agricultural and forest crops, pastures, stocks in storages. Their harmfulness is increased by the fact that voles and mice are capable of mass reproduction. Marmots, ground squirrels, 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.), carriers feed on their blood serious illnesses- ticks, fleas, lice, mosquitoes. Some predatory mammals and bats store and transmit rabies pathogens. Many of these infections constantly exist in nature, that is, they have a natural focality. People and pets can get sick if they enter the territory of a natural focus and come into contact with sick animals or vectors. The theory of natural focality of diseases was developed by the outstanding Soviet zoologist Acad. E. N. Pavlovsky and his students. This theory has become the scientific basis for organizing the fight against these diseases.

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

Ferrets, foxes, jackals can cause some harm to poultry farming, however, under natural conditions, they often feed on mouse-like rodents, and some also on carrion, etc. Wolves destroy many valuable wild and domestic animals, in some places it is necessary to limit their numbers, as well as the number of some others. predators, by shooting.

Fur farming

Fur farming in our country arose about 200 years ago, in the USSR this branch of animal husbandry began to develop intensively from 1928-1929, when the first specialized fur farms for the production of furs for export were created. Currently, fur farming is developing in three main areas: free, or island (this is how ungulates are bred mainly - deer, spotted deer, elk, which give antlers, skin and meat), semi-free (the main herd is kept in cages, young animals - in a limited area ) and cellular. The latter direction is the main form of modern industrial fur farming. On large fur farms they keep up to 100 thousand animals, and 85-90% of the total number of the main herd of females is mink of various colors. They also grow nutria, foxes, arctic foxes, sables, chinchillas, river beavers. 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 the globe More than 100 species of mammals have been completely destroyed; currently, about 120 species of mammals are under the threat of extinction. The problem of preserving and increasing the number of polar bears, tigers, snow leopard, bison, wild spotted deer, some species of whales and seals and other animals. For this purpose, back in the USSR, the Law "On the Protection and Use of the Wildlife" was adopted, in accordance with it, rare and endangered species of animals are entered in the Red Book of the USSR and the Red Books of the Union Republics. Shooting and trapping of rare and endangered species of animals is prohibited in our country, nature reserves, sanctuaries, and micro-reserves have been created where integral natural communities of animals are preserved.

Mammals are the highest class of vertebrates, which is characterized by a perfect development of the nervous system, a constant high body temperature and the ability to live birth.

Systematics.

Subclass Firstbeasts

Subclass Real Beasts

Infraclass lower marsupials

Infraclass Great Beasts

Currently, about 4000 species of mammals are known, which belong to 20-23 orders. The largest orders are rodents (1500 species), bats (1000 species). The smallest detachment - Single pass - 3 species.

External structure. Body sizes from 3.5 cm (baby shrew) to 35 m (whales). Most often, the head, neck and trunk are well separated, which is highly elevated on the front and hind limbs. On the head there are auricles - a characteristic feature of mammals. In some, the auricle is not developed (moles). The neck is usually of medium length, but can be relatively very long (giraffes) or short (cetaceans). The limbs are usually five-fingered. Their structure corresponds to the lifestyle of the animal. So, in cetaceans, the limbs are turned into fins, in seals - into flippers, in bats - into wings, etc. The tail is usually of medium length, but may exceed the length of the body (black rat), be very short (hares) or absent (human). The tail can perform a number of functions (beaver, muskrat, tree squirrels)

Covers. The body is covered with thick skin consisting of epidermis and cutis. Cutis has a fibrous structure and has a large number of sebaceous and sweat glands. The epidermis forms various horn formations: wool, needles (hedgehogs), scales (pangolin), shields (armadillo). On the fingers there are claws, nails; to the hoofed part of the fingers is reduced, and horny covers are formed - hooves. Horns form on the head of ungulates. The coloration of the covers is most often patronizing. At a certain time, molting occurs, which is sometimes accompanied by a change in hair color (ermine) and its structure (fox, squirrel). In mammals, there are also modified sweat glands in the skin - mammary glands. Under the skin, a number of mammals have a thick layer of fat, which performs the function of thermal insulation (seals, whales).

Skeleton mammals consists of five sections - cervical, thoracic (bearing ribs), lumbar (no ribs), sacral (4 fused vertebrae) and tail.

The skull is completely ossified. Its constituent bones are firmly connected to each other with sutures; the only moving part is the lower jaw. Teeth in mammals are most often differentiated into incisors, canines, and molars. Depending on the lifestyle, incisors (the upper jaw of cows), fangs (in rodents) may disappear. Teeth may be completely absent (some whales, pangolin, anteater). In toothed whales, numerous teeth have the same shape (differentiation is absent).

The ribs are joined by the sternum to form the ribcage. The sternum of bats carries the keel.

The skeleton of the fore and hind limbs is typical of terrestrial vertebrates. In whales, the hind limbs are reduced along with the pelvic bones. The shoulder girdle consists of the scapula and the clavicle (the latter may be absent, as, for example, in ungulates, carnivores).

muscles well differentiated. For mammals, the subcutaneous muscles are very characteristic, setting in motion certain areas of the skin and hair. In primates, mimic muscles reach a special development. Same way feature is the diaphragm - a partition between the chest and abdominal cavities, which is involved in the act of breathing.

Digestive system. The salivary glands open into the oral cavity and produce a number of enzymes. The distensible esophagus flows into the stomach, which can be simple, two-chamber (desmodes) and multi-chamber (ruminants). The length of the intestine depends on the type of nutrition of the animal. Herbivores have a well-developed caecum. The rectum opens into the anus. In some mammals (bats), the intestines are poorly differentiated.

Respiratory system. Paired or unpaired (in cetaceans) nostrils open into the nasopharynx leading to the larynx. The larynx of mammals is complex and consists of five main cartilages. The cricoid and paired arytenoid cartilages came from reptilian ancestors. In front, the larynx is covered by a large thyroid cartilage, characteristic only of mammals. Attached to this cartilage inside the larynx are the vocal cords, with which animals can make sounds over a very wide range. Another cartilage characteristic of mammals is the epiglottis, which, during swallowing, covers the entrance to the larynx and food slides down it into the esophagus. The trachea is provided with cartilaginous semirings. The lungs are placed in the chest cavity. The bronchi in the lungs branch into numerous bronchioles, ending in pulmonary vesicles - alveoli. Ventilation of the lungs is accomplished by changing the volume of the chest cavity due to the diaphragm and intercostal muscles.

Circulatory system. The heart is four-chambered. Only one aortic arch departs from the left ventricle, wrapping to the left. Red blood cells - erythrocytes - in mammals, unlike other classes of chordates, have the appearance of biconcave discs and lack nuclei.

Nervous system. The brain is highly developed. The huge hemispheres of the forebrain are covered with gray matter - the cortex. This type of fornix (roof) is called neopallium and is characteristic only of mammals. In a number of animals, the surface of the brain is covered with convolutions and furrows, which increase the area of ​​the cerebral vault. The cerebellum, which is responsible for coordinating the movements of the animal, is also highly developed. The midbrain is relatively underdeveloped. Olfactory lobes in different groups can be developed either strongly or weakly, depending on the lifestyle.

This structure of the brain provides the highest level of mental activity. It must be taken into account that the relative volume of the brain does not affect mental abilities; for example, a sheep has a relatively very large brain.

sense organs.

Organ of vision. The eyes are relatively simple. Accommodation is achieved only by changing the curvature of the lens. Many mammals have binocular vision (carnivores). In soil-dwelling animals, the eyes are very poorly developed (zokor, mole), or absent altogether (mole rats).

hearing organ It is represented by three departments: the outer ear (the ear canal), the middle ear (the tympanic membrane and three auditory bones - the stirrup, hammer and incus) and the inner ear (the cochlea and the organ of Corti). The hearing of many mammals is very sensitive. For example, bats navigate and hunt at night, relying solely on echolocation. A leather jacket, for example, can thus detect a stretched wire 0.1 mm thick at a distance of 3 meters. The organ of balance is also connected with the inner ear.

Olfactory organ located in the nasal cavity of mammals. Predators are especially good at smelling.

sense organs represented by vibrissae on the head in many mammals and outgrowths on the muzzle (in the star-nosed mole).

excretory system. Paired kidneys are located in the lumbar region. These are compact, often bean-shaped organs. Some mammals - pinnipeds, cetaceans - have multiple kidneys. The kidneys are connected by the ureters to the bladder, which opens into the urethra. This canal flows into the urogenital sinus.

reproductive system. In males, it is represented by paired testes, from which the vas deferens depart, flowing into the beginning of the urethra. This canal pierces the penis and opens outward.

In females, paired ovaries are developed, from which the oviducts (fallopian tubes) depart. The oviducts flow into the horns of the uterus, connecting into an unpaired vagina, opening into the urethra.

nutritional biology. Mammals are conventionally divided into three groups.

Carnivores. These animals are further subdivided into predatory(canine, mustelid, some whales, pinnipeds) and insectivores(hedgehogs, moles, shrews, pangolins, anteaters, bats). The first subgroup includes bats - desmods, feeding on the blood of warm-blooded, and the last - large toothless whales that feed on krill. Among carnivores, active hunters are mainly found, ambush predators are very rare.

Herbivorous - ungulates, many rodents, sloths, flying dogs.

Multi-eating that eat both animal and plant foods - primates, pigs, bears, rats.

Biology of reproduction. Among mammals, there are both monogamous and polygamous. Mating is preceded by courtship rituals, and even fights between males. After mating, the pair builds a shelter (nest). Often only the female does this. A number of species do not prepare for the appearance of offspring at all and give birth in them “on the go”. The timing of pregnancy depends on the size of the animal. For rodents - 18-20 days, for bears - 7-8 months, for whales - about a year. In some cases, latent pregnancy occurs. In ermines, for example, mating occurs in May-June, and childbirth occurs only a year later. In bats wintering in our latitudes, mating occurs in autumn, and fertilization occurs only in spring. Sometimes the male mates with newborn females (in some mustelids).

The embryo implants into the wall of the uterus, forming the placenta, and continues to develop. Thus, mammals are viviparous and only the most primitive lay eggs (echidna).

Cubs are born either blind and helpless (rodents), or sighted and able to follow their mother (ungulates). The female feeds the young with milk. Sexual maturity occurs within a period of 1 month (in small rodents) to several years (in large animals). Fertility from one cub (whales, elephants), up to 22 (rats).

Migrations. Some mammals migrate over long distances, such as whales. Northern bats are able to fly to regions with warm climate. Most mammals are either sedentary or migrate over relatively short distances.

Hibernation. A phenomenon characteristic of few mammals. Hibernation most often allows you to survive either winter cold or summer heat (gophers). Some mammals, for example, bats, fall into a very deep hibernation, finding suitable shelters for this - caves, cellars, cellars. The body temperature of the animal drops to +8..10°C (in summer - up to +40°C). Such hibernation continues in our region from the end of September to the end of May. Other mammals (bears, badgers, raccoon dogs) hibernate for the winter. Their body temperature does not drop. A high metabolic rate is provided by large reserves of fat that accumulate over the summer.

During hibernation, animals are able to periodically wake up. Some rodents store food (hamsters).

Origin. The ancestors of mammals were reptile-like animals. Among them, the most famous are cynognathus (195 million years ago) and foreigners (220 million years ago). After the extinction of the dinosaurs, mammals quickly occupied the empty ecological niches. Since then, this group has been on the rise.

Mammals are the most highly organized class of animals, especially the nervous system and sensory organs. Currently, about 5,000 of their species 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, adapted to different habitats and ways of feeding. All this gave rise to a variety of their forms. However, they all have many similarities.

Integuments of mammals

The body of mammals has a hairline, which primarily performs the function of thermoregulation. Among the hairs, there are longer and stiffer ones (awn) and shorter and softer ones (underfur). In some (mainly aquatic) species, hairline reduction 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.

mammalian 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 are descended from animal-toothed lizards, which separated from the main branch of reptiles at the beginning of their appearance. Thus, the animal-tooths retained a number of features of amphibians, including the way the skull is connected to the vertebra.

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

In the shoulder girdle, most mammals lack caracoids. Many also lack clavicles (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, as in reptiles.

There are fewer bones in the skull, 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 of them 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 secret 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. There is a caecum at the border of the small and large intestines. In the vast majority of mammalian species, the intestines end in the rectum, which opens outwards with a separate anus. However, monotremes retain a cloaca.

The circulatory system of mammals

In the circulatory system of mammals, there is a complete separation of 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 the process of evolution in birds. However, they retained the right aortic arch. Birds evolved from another group of ancient reptiles.

Arterial blood is pushed out of the left ventricle into the aorta, from which the carotid arteries originate, the dorsal aorta. Smaller arteries depart from them. Venous blood from the organs of the body is collected in the anterior and posterior vena cava, which flow 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 is collected in the pulmonary vein, which flows into the left atrium.

Mammalian erythrocytes do not contain nuclei, which results in more efficient oxygen transport.

Respiratory system of mammals

All mammals, including those who have switched to an aquatic lifestyle, breathe with their lungs. The lungs have an alveolar structure, when the bronchi included in them branch into smaller and smaller ones, ending in bubbles-alveoli, 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 thoracic and abdominal cavities.

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

excretory system of mammals

In mammals, pelvic kidneys develop, from which the ureters depart, flowing into the common bladder. Bladder opens outwards with an independent opening (except for single-pass).

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

The main excretion product is urea.

Nervous system and sense organs

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

An important role in the life of mammals is played by smell and hearing. 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 stiff hair (whiskers) on their muzzle - 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.

mammalian 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).

Caring for offspring is characteristic, a long period of individual development (usually correlates with the size of the animal and the complexity of behavior - the larger or more complex, the children's period longer). All mammals feed their young with milk.

Systematics of mammals

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

Oviparous include the platypus and echidnas that live in Australia and the islands adjacent to it. These animals do not have live birth. Instead, they lay eggs (but by the time of laying, the embryo in the egg is already well formed). They have a cesspool, caracoids, less constant body temperature. Thus, oviparous combine the characteristics of mammals and reptiles.

Marsupials are common in Australia, South and partly in North America. In Australia, due to its isolation, in the process of evolution, many species of marsupials (marsupial predators, rodents, herbivores) similar to placental ones appeared. A typical representative is a kangaroo. In marsupials, a full-fledged placenta is not formed. The cub is born severely premature and is worn in a bag (a special skin fold on the belly), attached to the nipple.

The most diverse placental mammals. Their taxonomy is quite complex and has been somewhat changed recently. Thus, the Pinniped seals and walruses, previously identified as a separate order, are now assigned to the Carnivora order.

In total, there are about 25 orders of mammals, whose representatives live in our time. The most numerous detachment is rodents (more than 2 thousand species). Its representatives are ubiquitous. Other orders: Lagomorphs, Bats, Insectivores, Carnivores, Proboscis, Artiodactyls and Odd-toeds, Primates, Cetaceans, etc.