Order Carnivorous mammals: classification, distribution, characteristics and significance. Squad Predatory. Structural features, biology and practical significance Brief ecological and faunal characteristics of the research area

1.1.1. Anatomical features skeletal structure

Predatory fur-bearing animals have a flat and elongated skull, a small cranium. The jaw is rigidly attached to the jaw joint by roller-shaped articular processes. Shifting it to the side, moving forward and backward is impossible, which determines a reliable grip with jaw pincers. The upper jaw is slightly pushed forward, due to which the teeth of the upper jaw slide over the teeth during closure lower jaw and cut the meat like scissors. Nutria have a small skull with a developed facial skull. The gnawing teeth are large, orange in color, and strongly pushed forward. Fur-bearing animals (except nutria) are characterized by the replacement of milk teeth with permanent ones.

The spinal column in fur-bearing animals, as in domestic animals, is divided into: cervical, thoracic, lumbar, sacral and caudal sections. All animals have 7 cervical vertebrae; in arctic foxes, foxes and nutria – 13; minks, ferrets (furo, fretka, thorefretka or thorzofretka) and sables have 14 thoracic vertebrae.

The lumbar region is represented by 6...7 vertebrae, the sacrum is formed by three fused bones (iliac, ischial and pubic).

In the caudal region of foxes, arctic foxes, ferrets and minks there are 20...23 vertebrae; in sables – 15...16; Nutria have 25 vertebrae.

The chest of arctic foxes and foxes is formed by 13 pairs of ribs (of which 5 pairs are false); in minks, ferrets and sables - 14 pairs (5 pairs of false); in nutria - 13 pairs (6 pairs of false ribs).

The skeleton of the limbs of the shoulder girdle is formed by the scapula, humerus, bones of the forearm (radius and ulna), wrist, metacarpus and phalanges of the fingers. Nutria also have a collarbone, connected on one side to the scapula, and on the other to the first rib.

The pelvic girdle consists of the sacrum, femur, shin bones (tibia and fibula), tarsus, metatarsus and phalanges.

The fore and hind limbs of predatory animals are approximately the same length (in nutria, the hind limbs are longer than the front). The limbs of arctic foxes are longer than those of foxes.

Minks, ferrets and sables each have 5 toes; foxes and arctic foxes have 5 fingers on their forelimbs, and 4 fingers on their hind limbs; Nutria have five-fingered limbs, with 4 fingers of the hind limbs connected by a swimming membrane.

1.1.2. Features of digestion in fur-bearing animals

In natural habitats, fur-bearing animals of the order of carnivores feed mainly on animal feed, which left its mark on the structure of the skull, teeth and various parts of the digestive tract.

The chewing apparatus of carnivores is poorly adapted to chewing food. They have fewer molars than herbivores, which are used for grinding food. Molars have sharp, jagged edges and are used to grab food and tear it into pieces. In the canine family, the raccoon dog is an exception. It is omnivorous, has small canines, underdeveloped upper teeth, and the surface of the lower molars is smoothed.

The dental system of rodents - nutria, muskrats, chinchillas - are herbivorous animals. Their incisors are rootless and grow continuously throughout their lives. There is only one pair of incisors in the upper jaw, there are no fangs, and the molars are adapted for grinding food. The articular head of the lower jaw is elongated in the longitudinal direction, due to which the jaw can move back and forth, grinding coarse plant food. Behind the incisors, nutria can close their lips tightly, which allows them to gnaw plants underwater.

The oral cavity of carnivores has a relatively small capacity, as a result of which food is almost not chewed, but is immediately swallowed.

The stomach of these animals is simple with thin elastic walls and underdeveloped muscles; it does not participate in softening and grinding food. Nutria have a stomach of a simple digestive type, the cecum reaches 40...45 cm.

The intestines of carnivores are much shorter than those of herbivores. The short intestinal length of carnivores determines the rapid passage of food through the gastrointestinal tract. Food is completely digested in minks and ferrets - after 15...20 hours; in arctic foxes, foxes and sables - after 24...30 hours. Due to the small length and capacity of the large intestine, the very underdeveloped cecum in foxes and arctic foxes (length 5...8 cm), and its complete absence in minks, ferrets and sables, bacterial digestion of food does not occur. This also explains the poor digestibility of plant foods, especially by minks and ferrets, which causes a constant deficiency of B vitamins.

Of the nutrients, carbohydrates are digested worse than protein and fat (in minks and ferrets this digestibility is somewhat lower than in arctic foxes and foxes, and in the latter it is lower than in rodents). Fur-bearing animals practically do not digest fiber from plant foods, but they need it in small doses to loosen food and improve intestinal motility.

Nutria and chinchillas feed mainly on plant foods. Chinchillas and marmots raised in captivity eagerly eat various parts of many species of herbaceous, shrubby, woody plants, their seeds and fruits.

The intestines of fur-bearing animals contain lymphoid tissue (lymphoid plaques), which prevents the penetration of foreign substances through the intestinal wall, regulate the proliferation of microorganisms, and are directly involved in digestion.

1.1.3. Features of growth and development of fur-bearing animals

Fur-bearing animals have some characteristics that distinguish them from farm animals. In predatory fur-bearing animals, the seasonality of biological cycles is much more pronounced than in other farm animals:

– limited breeding season;

– molt occurs at certain times hairline;

– seasonal changes in metabolism are observed.

Important biological feature fur-bearing animals is characterized by their high growth rate in the first months of life. In the growth of young animals, certain stages are observed that have big influence on the development of the body and the formation of productive qualities. An example is the influence of inhibition of growth rate during the suckling period on the final size of animals, underfeeding or insufficiency of certain nutritional factors in the autumn period on the formation of reproductive qualities of animals. Puppies of predatory fur-bearing animals are born helpless. They are blind, with a closed ear canal, no teeth, with very short, sparse hair, but they develop quickly.

The weight of minks and ferrets at birth is 9...15 grams, 20 days after birth it increases 10 times, at 2 months of age their weight is 40%, and at 4 months - 80% of the weight of an adult animal. Mink and ferret puppies erupt their teeth at 16–20 days of age. The transition of puppies to an independent type of feeding after weaning is accompanied by a sharp decrease in the growth rate, but after 10 days the growth rate increases again. At the age of 7...8 months, the increase in body weight of minks and ferrets stops, only seasonal fluctuations are noted.

Fox and arctic fox puppies grow somewhat slower (at birth they weigh 80...100 grams). By the age of 20 days, the weight of arctic foxes increases 7.5 times; by the time of depositing, they accumulate almost a fifth, and by 4 months of age - 80% of the mass of adult animals. In the first days of life, their limbs grow most rapidly, then the head and, finally, the torso. By 5...6 months of age, Arctic fox and fox puppies acquire the body proportions of adult animals. The replacement of baby teeth with permanent ones in fox and arctic fox puppies ends at the age of 3.5 months.

Nutria puppies are born well developed (weigh 150...200 grams), pubescent, can swim, and after two days they begin to eat food. Nutria grow slowly, but develop quickly. They reach sexual maturity at 3...4 months, but continue to grow up to one and a half years. Nutria reproduce throughout the year.

The weight of newborn caged chinchilla puppies reaches 35...50 grams, the lactation period lasts two months, but the puppies begin to eat food already 5...7 days after birth.

In caged sables, a parabolic type of growth is observed (intensive growth occurs until 3 months of age). The linear growth of sables almost stops by the age of 6 months, and body weight continues to increase. The increase in these indicators in males is more intense than in females, up to 180 days of age. By the end of the first month, teeth erupt - on the 28th...30th day.

The auditory canals of minks, ferrets and sables open in the last week of the first month of life. The growth of young animals is most intense in the first months of life, so feeding conditions should not hinder the potential development of animals. Stunted growth is often not compensated for, which is reflected in the reproduction rates of animals and the size of their skins.

1.1.4. Seasonal changes in metabolism

The intensity of metabolism and energy in animals varies in different seasons of the year. Despite domestication, they retained the adaptive reactions that developed during the process of evolutionary development to seasonally changing natural food conditions. There is a certain connection between seasonal fluctuations in energy metabolism in predatory animals and feeding conditions. Thus, a decrease in metabolic rate in autumn months with the abundance of food in nature, it ensured the accumulation of reserve fat and other nutrients in the body for use in winter and best development winter pubescence. Further decrease in metabolism in winter months when feeding conditions worsened, it was determined by the need to reduce the body’s nutritional needs at that time. Organizing feeding in accordance with these established fluctuations in metabolism - increasing the fatness of animals in the fall, and reducing their live weight in the winter months - is, as practice has shown, important for ensuring normal reproduction and obtaining good quality skins. IN summer months metabolism is most intense, it decreases in the fall, is lowest in the winter, and rises again in the spring. In accordance with changes in metabolism, the live weight of animals also changes. In summer it is the smallest, and in November–December it is the greatest. Seasonal changes in fat deposition reflect the characteristics of thermoregulation in fur-bearing animals. Their accumulation of fat by winter allows them to reduce heat transfer, and therefore energy consumption during the cold season; a decrease in the amount of fat in summer and less hair during this period cause increased heat transfer.

In minks, seasonal changes in metabolism are clearly expressed, in sables there is no such clear seasonal metabolism, and in nutrias, the metabolism of the seasons hardly changes (with the same feeding, their live weight in summer is about 10% higher than in winter, i.e. in Their metabolism retains the characteristics of animals of the southern hemisphere - the homeland of nutria is South America).

1.1.5. Shedding hair in animals

Animals shed hair twice a year - in the spring the winter hair falls out and the summer hair grows, in the fall the summer hair is again replaced by winter hair. Winter hair falls out and is replaced by short dark hair; in July, short hair covers the animal completely. In the second half of summer it begins to fall out, and this molt ends in October. By this time, the coat consists of short, fast-growing winter hairs. The seasonality of changes is most governed by the duration daylight hours– the most constant of external stimuli. By artificially changing the length of daylight hours, it is possible to slightly shift the natural timing of maturation of the reproductive system and the duration of pregnancy.

Such external conditions, such as: the composition and amount of feed, temperature, etc., also affect the course of life processes, but they are not constant.

The order Carnivora unites representatives of the class Mammals, who consume mostly animal food. The wolf and the fox, the tiger and the lion, the marten and the badger are known to everyone. This is not surprising, because Carnivores have adapted to living on all continents except the coldest - Antarctica. Let us briefly consider what information biology has collected to date about these animals.

Squad Predatory

First of all, they are united by the nature of the food. It is not just of animal origin. All representatives of the Predatory squad themselves attack their victims, killing them. Some of them feed on carrion, thereby clearing their habitats of rotting organic remains.

The main characteristic of the Carnivora order is associated precisely with the structural features that allow them to hunt. Therefore, they all have a developed brain, a strong trained body, and well-developed differentiated teeth. The fangs with which they grab and tear apart prey are especially prominent. On each side, one molar is modified into the so-called carnivores. With their help, it is even possible to crush large bones and tear powerful tendons - it is so sharp.

Carnivores are also distinguished from other mammals by their highly developed nervous system, especially the brain. This causes complex forms of behavior of these animals.

Carnivores are quite diverse and number about 240 species. Therefore, a number of other families are distinguished in this order.

Wolf family

When characterizing the order Carnivores (mammals), they first of all mention the family, which received its name thanks to the tireless forest orderly. It's about about the wolf and its relatives: fox, jackal, arctic fox, raccoon and domestic dogs.

All of them are medium in size and have fairly long limbs. The structure of the musculoskeletal system and muscular system allows them to pursue their future prey for a long time and tirelessly.

The strongest and most agile among the representatives of this group is the wolf. Animals prefer to live in large flocks, the number of individuals in which reaches forty. Wolves are not only excellent hunters, but also dangerous predators which can even attack humans. They are rightfully considered to eat large amounts of carrion.

But the fox can eat not only animal food. Her favorite treat is sweet and juicy fruits forest plants. Foxes live in pairs or entire families. People especially appreciate the beautiful, warm and fluffy fur of these animals.

Cat family

We continue to study the Carnivora order using the example of... a domestic cat. What kind of predator is this? The real one! Its ancestor is the forest wild cat. And modern pets are the result of their domestication.

Basically, representatives are united by large body sizes with elongated limbs, which end in retractable sharp claws. Has everyone seen how a cat hunts a mouse? She does not catch up, but lies in wait for her prey. The same behavior is typical for larger cats: tiger, lynx, lion.

Most representatives of this family live in the tropical and subtropical climate zones of our planet. And here is the owner of the taiga Far East. This is one of the most large predators, second only to the polar bear in mass. Within the boundaries of its range, it always occupies a dominant position. This also applies to links food chains, since tigers also hunt other predators, such as wolves.

Miracles of selection

Since the lion and tiger are the most prominent representatives all over the planet, genetic scientists have tried to create their hybrids. This experiment ended quite successfully, since the crossing resulted in viable individuals with new properties compared to the original forms. Thus, a liger is a hybrid of a lion and a tigress, capable of unlimited growth. In nature, this trait is characteristic of plants and fungi. The liger grows throughout its life, sometimes reaching a length of up to 3 meters.

Typically, interspecific hybrids are not capable of producing fertile offspring. Tiger Lion is an exception to this rule. This is practically the only case in selection. Females obtained by crossing a tiger and a lioness are capable of procreation.

Family Kunya

We continue to consider the order Carnivorous mammals using the example of a family that unites individuals with valuable fur. Otter, marten, ermine, mink, ferret - this is far from full list representatives of the Kunya family. Many of them are excellent tree climbers, and otters are excellent swimmers. Another representative of the mustelids is the badger. He especially values ​​meat, which is eaten, and fat, which has healing properties.

Bear family

The Predatory squad has mastered everything climatic zones. Its representatives can be found even in the cold expanses of the Arctic. It is there that the largest representative of predatory mammals lives - the polar bear, whose weight can reach 750 kg. It swims well, hunting fish and pinnipeds.

But in the forests, the Predatory squad is represented by another animal - the brown bear. It can feed on both plant and animal foods, attacking deer or wild boars. In winter, this one hibernates, and in summer it leads an active lifestyle. It is hunted for its valuable meat and skin.

The order Carnivora unites a number of families of the class Mammals, whose diet is dominated by animal food. These animals have well-developed sharp teeth for hunting. Many species are valued by humans for their valuable fur, meat and fat. Therefore, at present, many species of predatory mammals are in need of protection.

Ecological groups of amphibians. Morphophysiological features.

Evolution of methods of reproduction in vertebrates.

In the evolution of vertebrates - from fish to warm-blooded animals - there is a tendency towards a decrease in the number of offspring and an increase in their survival.

Sexual reproduction occurs with the participation of germ cells (gametes), after the fusion of which a fertilized egg is formed. A special type of reproduction is parthenogenesis, when a new organism develops from an unfertilized egg. Some animals have alternating generations. In its life cycle, each animal organism goes through stages of individual development (ontogenesis), namely:

embryonic development;

immature (from birth to puberty);

sexually mature;

aging.

Embryonic development begins with fertilization of the egg, its further fragmentation with the formation of a blastula (consists of one row of cells), which, as it develops, forms the germ layers - gastrula, from germ layers tissues and organs are formed adult. The process of tissue formation is called histogenesis, and the process of organ formation is called organogenesis. Embryonic development ends with the formation of an embryo. In many animals, embryonic development ends with the formation of a larva, which differs from adults not only in structure, but also in its way of life. This method of development (from larva to adult) is called metamorphosis or indirect. Development, when young individuals are born similar to adults, is called direct.

Each type of organism is characterized only by its life cycle - the totality and sequence of development of individual phases. It can be simple (with direct development) and complex, which is associated with metamorphosis, alternation of generations, etc.

Animals are characterized by a process such as regeneration - the renewal of lost or damaged organs, as well as the renewal of a whole organism from its part. For example, in a hydra the body can be renewed from 1/200 of its part, in a planaria - from 1/100, in a lizard the tail can be renewed, etc. With an increase in the level of organization of animals, the ability to regenerate decreases.

Terrestrial-arboreal animals;

Animals of open spaces;

Burrowing animals;

Aquatic and semi-aquatic mammals;

Flying mammals;

Typical terrestrial mammals:

1. They have a short body and weak legs.

2. They have a proportionally built body and a developed neck.

3. More often these are animals from the order of Rodents.

4. Represented mainly by predators.

2. Subterranean mammals:

1. They have a short body, ridged, short fur, thick, without lint, growth direction.

2. The ears and vision are well developed.

3. Representatives are foxes, hares, badgers.

3. Aquatic mammals have:

1. Fish-shaped body, without a cervical region, horizontal caudal fin.

2. Small ears, short, very thick fur, developed subcutaneous fat.

3. Limbs that have turned into fins.

4. The group includes otters, sharks, dolphins, seals, and walruses.

14.2.1 Skin

The skin of mammals has the following functions:

Confinement and protection of the body from the surface;

Participation in thermoregulation;

Involvement in the expression of sexual dimorphism;

Participation in respiration and excretion.

Mammalian skin consists of the epidermis, which is on the outside, and the cutis, which is on the inside.

The epidermis contains two layers: deep (germinal) and superficial (horny). In the deep layer, the cells are cylindrical or cubic in shape. In the stratum corneum, the cells are flat and contain keratohyalin. These cells slough off as they die. The epidermis gives rise to all derivatives of the skin - horns, hooves, hair, claws, scales, and various glands.

The cutis, or skin itself, consists of fibrous connective tissue, contains blood vessels, the bases of hair follicles and sweat glands. Fat is deposited in the lower part of the cutis, which is loosely fibrous. The subcutaneous fat layer is well developed in seals, whales, ground squirrels, marmots and badgers.

Species living in cold countries have lush hair and thin skin.

Thin skin in a hare, so a predator can miss it by tearing off a piece of skin.

Not all animals have hair. Dolphins and whales do not have it. Pinnipeds have reduced hair.

The structure of hair is as follows. Hair consists of a trunk and a root. The trunk protrudes above the skin, and the root sits in the skin. The trunk has a core, a cortical layer and a skin. The core is a porous fabric that provides low thermal conductivity of the hair. The cortex layer is dense and gives the hair strength. The skin is thin and protects hair from mechanical and chemical influences. The upper part of the root is cylindrical in shape, and the lower part expands into a bulb enclosing the hair papilla. The papilla contains blood vessels. The lower part of the hair sits in the hair follicle, where the ducts of the sebaceous glands open.

The hairline consists of different types hair: 1) downy hair, or fluff; 2) guard hairs, or awn; 3) sensory hairs, or vibrissae.

In most species, the basis of the coat is thick, low down (undercoat). Underground animals (mole, mole rat) do not have guard hairs. In adult deer, wild boars, and seals, the undercoat is reduced (the coat consists mainly of awns).

Hair change (molting) occurs in some species twice a year - in spring and autumn (squirrel, fox, arctic fox, mole). Other species shed once a year: the old fur falls out in the spring, develops in the summer and creates new fur by the fall (ground squirrel).

Vibrissae are very long, coarse hairs that perform a tactile function. They sit on the head, on the lower part of the neck, on the chest, and in some climbing arboreal forms, on the belly (squirrel). At the base of the hair follicle and in its walls there are nerve receptors that perceive the contact of the vibrissa rod with foreign objects.

Bristles and needles are modifications of hair. Other horny derivatives of the epidermis are represented by horny scales, nails, claws, hooves, hollow horns, and a horny beak. Scales in development and structure are similar to those of reptiles. Found on the paws of many mouse-like rodents and on the tail of many marsupials, rodents and insectivores.

Nails, claws, hooves are horny appendages on the terminal phalanges of the fingers. Climbing mammals have sharp, curved claws. In burrowers, the claws are flattened and widened. Large mammals that run fast have hooves. At the same time, species that walk through swamps have wider and flatter hooves. Steppe and mountain species (antelope, sheep and goats) have small and narrow hooves.

The horns of bulls, antelopes, goats and rams develop from the epidermis and sit on bone rods - independent bones fused with the frontal bones. Deer antlers are of a different nature: they consist of bone material and develop from the cutis.

There are 4 types of skin glands. Sweat - open on the surface of the skin, release sweat (water, urea, salts) and serve to cool the body by evaporating water, i.e. perform thermoregulatory and excretory functions. They are absent in whales and lizards; Rodents have them only on their paws, groin and lips. Dogs and cats have very few sweat glands. The sebaceous glands open into the funnel of the hair follicle. Their secretion - lard - lubricates the hair and epidermis of the skin. Odorous glands are modified sweat or sebaceous glands, and sometimes a combination of both. The anal glands of mustelids have a very pungent odor, especially those of skunks, or American stink bugs. It is assumed that these glands are important during the rut, because stimulate sexual arousal. Lacteals are modified sweat glands. In the echidna, the glandular field is located in the pouch for gestation of the egg and the young; in the platypus, the glandular field is located directly on the belly; in marsupials and placentals, the ducts of the mammary glands open on the nipples.

In mammals, the skin and its derivatives provide mechanisms of physical thermoregulation by regulating heat transfer. When skin vessels dilate, heat transfer increases sharply, and when they narrow, it decreases. Cooling of the body also occurs when water secreted by the sweat glands evaporates from the surface of the skin.

The density and height of hair in northern species varies significantly with the seasons. Animals living in the tropics have more sweat glands than, for example, those living in England (zebu and shorthorn).

The skin is involved in chemical signaling. The secretions of the skin glands, like other odorous secretions, are an important means of intraspecific communication. The signal is transmitted over long distances and persists for a long time. Families of animals often mark their territory, and they also leave a mark on the cubs, so they can be easily found and distinguished.

Odor signaling is critical for the development of mammalian behavior.

14.2.2 Mammalian muscular system

Contains many diversely located muscles. Characterized by the presence of a thoraco-abdominal barrier - the dome-shaped muscle of the diaphragm, which has great importance to carry out the act of breathing. The subcutaneous muscles that move the skin are well developed. In hedgehogs, it provides the ability to curl up into a ball. “Bristling” (for example, when frightened) is also associated with this muscle. On the face, such muscles are represented by facial muscles (well developed in primates).

3. Mammal skeleton

Character traits in the structure of the skeleton of mammals are as follows. The vertebrae are platicelous (they have flat articular surfaces). Between the vertebrae are cartilage discs (menisci).

The spine is divided into cervical, thoracic, lumbar, sacral and caudal sections. The number of cervical vertebrae is constant - 7, the 1st and 2nd cervical vertebrae are well defined - atlas And epistrophy. Only the manatee has 6 cervical vertebrae, and some species of sloths have 6-10 cervical vertebrae. There are 12-15 vertebrae in the thoracic region (one of the armadillos and bottlenose whales has 9, and some sloths have 24).

The sternum has a body, a xiphoid process and a manubrium. U bats and in burrowing animals the sternum bears a keel for attaching the pectoral muscles (as in birds). In the lumbar region there are 2-9 vertebrae, they bear rudimentary ribs. There are 4 fused vertebrae in the sacrum (2 are truly sacral, 2 are caudal vertebrae fused to the sacrum). Carnivores have 3 sacral vertebrae, the platypus has 2 (like reptiles).

The skull has a fairly large braincase, and it is quite well developed in comparison with the facial part of the skull. The number of individual bones in the skull is less than in lower groups of vertebrates, because the bones grow together into complexes (for example, the ear bones grow together into a single petrous bone. The sutures between the bone complexes heal quite late, which contributes to an increase in the volume of the brain as the animal grows. In the occipital region, there is a single occipital bone with two condyles for connection with the atlas. In the facial region in the skull section, the zygomatic arch characteristic of mammals is formed from the zygomatic processes and zygomatic bones.The development of the secondary bony palate is characteristic (from the palatine processes of the premaxillary and maxillary bones and palatine bones), so the choanae open behind the palatine bones, and breathing is not interrupted at the moment of chewing the food bolus. There are 3 auditory ossicles in the inner ear: the malleus, the incus and the stapes.

The shoulder girdle contains a scapula and a rudimentary coracoid at its base. The clavicle is present only in mammals whose forelimbs perform a variety of complex movements (monkeys).

The pelvic girdle consists of 3 paired bones: iliac, ischial and pubic. In many species these bones are fused into a single innominate bone.

The skeleton of paired limbs retains all the basic structural features of a typical five-fingered limb. At the same time, in terrestrial forms the proximal sections are elongated: the femur and tibia. In aquatic animals, these sections are shortened, and the distal ones (metacarpus, metatarsus, phalanges of the fingers) are elongated. In fast runners, the tarsus, metatarsus, carpus and metacarpus are located almost vertically (dog); in the most advanced runners (ungulates), the first toe atrophies, and the third toe (odd-toed ungulates) or the 3rd and 4th toes (artiodactyls) receive predominant development.

3. Digestive organs of mammals

The digestive tract of mammals is longer, better differentiated, and has more developed digestive glands. The alimentary tract consists of the following sections:

1) oral cavity,

2) pharynx,

3) esophagus,

4) stomach,

5) intestines.

In front of the oral cavity is preoral cavity(vestibule of the mouth), which is limited by the fleshy lips, cheeks and jaws. The vestibule of the mouth serves to temporarily reserve food. Monotremes and cetaceans do not have fleshy lips. There are 4 pairs of salivary glands in the oral cavity; here food is mechanically crushed and chemically processed. The salivary glands are especially developed in ruminants (a cow secretes up to 56 liters of saliva per day).

Mammals are heterodonts; they have teeth: incisors, canines, premolars (false molars) and molars. The number of teeth, their shape and function are different. The teeth are thecodont (sit in the cells of the jaws), the dental system is diphyodont (teeth change once in a lifetime). The tongue is muscular, used for grasping food, lapping water, and turning food in the mouth.

The pharynx lies behind the oral cavity. The entire upper part of the internal nostrils and Eustachian tubes open. On the lower surface of the pharynx there is a gap leading to the larynx.

The esophagus is well defined, contains smooth muscle, and in ruminants it is also striated, and this allows food to be regurgitated.

The stomach is in the form of a simple sac in monotremes; in most mammals the stomach is divided into sections. Complex stomach in ungulates. It consists of 4 sections: 1) scar; 2) grids; 3) books; 4) rennet. In the Rumen, feed masses ferment under the influence of saliva and bacteria. From the rumen, food goes into the mesh, and from there it is regurgitated back into the oral cavity. Here the food is crushed by the teeth and abundantly moistened with saliva. The resulting semi-liquid mass flows through a narrow channel from the esophagus into the book, and from there into the abomasum (glandular stomach).

The intestine is divided into thin, thick and straight sections. In species that eat rough plant food, at the border of the thin and thick sections there is a long and wide cecum (in some animals - hares, prosimians - it ends in a vermiform appendix). Plant food ferments in the cecum. In carnivores it is poorly developed or absent. Herbivorous species have longer intestines than omnivores and carnivores.

Many species of predators and ungulates go to water. Others have enough water in juicy foods. There are those who never drink and eat very dry food (desert rodents). They are supplied with metabolic water. When used in 1 day 1 kg. 1 liter of fat is formed. water, 1 kg. starch – 0.5 l, 1 kg. proteins – 0.4 l.

Under the diaphragm in mammals lies the liver, the bile duct of which flows into the first loop small intestines. The pancreatic duct, which lies in the fold of the peritoneum, also flows here.

3. Respiratory organs of mammals

The main respiratory organ in mammals is the lungs. The role of the skin in gas exchange is insignificant.

The upper larynx is complicated; at its base lies the cricoid cartilage, and the walls are formed by the thyroid cartilage, which is characteristic only of mammals. Above the cricoid cartilage there are paired arytenoid cartilages; the epiglottis is adjacent to the anterior edge of the thyroid cartilage. Between the cricoid and thyroid cartilages there are small sac-like cavities - the ventricles of the larynx. Between the thyroid and arytenoid cartilages lie the vocal cords.

The trachea and bronchi are well developed. The smallest branches of the bronchi - bronchioles - end in alveoli. Blood vessels branch in the alveoli. The huge number of alveoli forms a large surface for gas exchange. The exchange of air in the lungs is caused by a change in the volume of the chest, resulting from the movement of the ribs and a special muscle - the diaphragm. The NPV depends on the size of the animal (the smaller it is, the greater the NPV). Ventilation of the lungs not only determines gas exchange, but is also important for thermoregulation (especially for species with underdeveloped sweat glands. They cool the body with the help of polyps, when water vapor is exhaled with air.

14.2.6 Circulatory system mammals

There is only one aortic arch (like in birds), but the left one. It originates from the left ventricle. The innominate artery arises from the aorta, which divides into the right subclavian, right carotid and left carotid arteries. The left subclavian artery departs from the aortic arch independently. The dorsal aorta lies under the spine and gives off a series of branches to the viscera and muscles. The venous system is characterized by the absence of portal circulation in the kidneys. The left anterior vena cava usually merges with the right one, which flows into the right atrium.

Cardiac index (relative heart mass expressed as a percentage of total mass body) in the sperm whale is 0.3, and in the common shrew - 1.4. This index depends on physical activity. The more mobile the animal, the higher it is. In domestic animals, the relative size of the heart is 3 times smaller than in wild animals (rabbit and hare).

Blood pressure in mammals is as high as in birds. In a rat it is 130/90 mmHg, in a dog it is 112/56.

Total Mammals have more blood than vertebrates of lower groups, and the oxygen capacity of the blood is higher, because it contains quite a lot of hemoglobin (10-15 g per 100 cm 3). In aquatic and semi-aquatic mammals, when immersed in water, the heart rate decreases, which slows blood flow, and blood oxygen is used more fully. In animals immersed in water for a long time, peripheral blood circulation is switched off, but the blood supply to the brain and heart remains at a constant level.

14.2.7 Mammalian nervous system

In mammals, the volume of the cerebral hemispheres and cerebellum is increased (due to the growth of the roof of the forebrain). Because Mammals have a developed cerebral cortex, with gray matter located on top of white matter. The centers of higher nervous activity are located in the cerebral cortex. Associated with the progressive development of the cerebral cortex challenging behavior animals. The cerebral cortex is connected by a commissure of white nerve fibers- corpus callosum. The cerebral cortex of most mammals is powerful and consists of 7 layers, covered with grooves and convolutions. The diencephalon is covered from above by the cerebral hemispheres. The pineal gland, pituitary gland and hypothalamus are small, but perform very important functions. The midbrain is divided into 4 tubercles. The cerebellum is large and divided into several sections (this is due to the very complex nature of movements in animals). The medulla oblongata contains the nuclei of the centers of respiration, blood circulation, digestion and other important reflexes.

14.2.8 Mammalian sensory organs

The olfactory organs are very well developed in mammals, because they recognize each other and enemies, find food by smell - several hundred meters away. Fully aquatic (whales) have a reduced sense of smell, but seals have a very acute sense of smell. In mammals, a system of olfactory shells was formed, and the volume of the olfactory capsule increased. Some animals (marsupials, rodents, ungulates) have a special olfactory organ - the Jacobson's organ, which opens independently into the palato-nasal canal, being a separate section of the olfactory capsule. The Jacobson organ recognizes the smell of food when it is in the mouth.

The animals' hearing organs are also very well developed. If the lower classes have developed the inner and middle ear, then in mammals two more new sections have been developed: the external auditory canal and the auricle. . The auricle significantly enhances the subtlety of hearing; it is especially well developed in nocturnal animals, forest ungulates, and desert dogs. Aquatic and underground animals (whales, most pinnipeds, mole rats) do not have an auricle. The ear canal is separated from the middle ear by the eardrum. The middle ear has 3 auditory ossicles (not 1, like in amphibians, reptiles and birds). The malleus, incus and stapes are movably connected, the stapes rests against the oval window of the membranous labyrinth of the inner ear. This ensures more perfect transmission of the sound wave. In the inner ear, the cochlea is highly developed and there is the organ of Corti (the organ of hearing, consisting of the finest fibers stretched in the canal of the cochlea).

Many mammals are capable of echolocation - bats, cetaceans (dolphins), pinnipeds (seals), shrews. When locating, dolphins make sounds with a frequency of 120-200 kHz. And they can locate schools of fish from a distance of up to 3 km.

The organs of vision are not as important in the life of mammals as they are in the life of birds. Animals pay little attention to stationary objects. Forest animals have less acute vision than animals of open landscapes and nocturnal animals. Accommodation in mammals occurs only by changing the shape of the lens under the action of the ciliary muscle. Color vision in mammals is poorly developed compared to birds. Almost the entire spectrum is distinguished only by the great apes of the Eastern Hemisphere. And in the forest polecat, for example, color vision was not detected at all.

Feature organs of touch in mammals - the presence of vibrissae (tactile hairs).

14.2.9 Excretory system mammals

The kidneys in mammals are pelvic - metanephric. The trunk buds are formed embryonically, but are later reduced. The kidneys of animals are bean-shaped or lobular in shape, with a smooth or tuberous surface; in some species they are divided by interceptions into lobes. Outer layer kidneys - cortical - contains convoluted tubules, starting with Bowman's capsules, inside which are Malpighian corpuscles (tangles of blood vessels). Filtration occurs in the glomeruli, and blood plasma is filtered into the renal tubules (this is how primary urine is formed). In the collecting ducts of the inner layer - the medulla - reabsorption from primary urine, water, sugar and amino acids occurs. This is how secondary or final urine is formed. The smaller the animal, the larger the size of the kidneys in relation to the total body weight.

The main end product of protein metabolism in mammals, as in fish and amphibians (unlike reptiles and birds), is not uric acid, but urea. This type of protein metabolism in mammals is associated with the presence of the placenta, through which the developing embryo can receive unlimited amounts of water from the mother’s blood. Toxic products of protein metabolism can be excreted from the embryo through the placenta indefinitely. Urea is much more toxic than uric acid, but this type of exchange requires a very large consumption of water to excrete urine. This is also evidence of the closeness of mammals to amphibians.

In the medulla of the kidneys there are straight collecting tubules, which are collected in pyramids and open at the ends of the papillae, protruding into the renal pelvis. The ureter departs from the renal pelvis, it flows into the bladder, and from there urine is excreted through the urethra.

The excretory function is partially performed by the sweat glands, through which solutions of salts and urea are excreted. About 3% of the nitrogenous products of protein metabolism are excreted this way.

14.2.10 Mammalian reproductive system

The male gonads are called testes and are oval in shape. In most animals (except monotremes, some insectivores, edentates, elephants, cetaceans) they are initially located in the body cavity, and as puberty they descend. Through the inguinal canals into the scrotum. Adjacent to the testis is the appendage - a ball of convoluted seminiferous tubules of the testis. The appendage is homologous to the anterior part of the trunk kidney. The vas deferens extends from the epididymis, flowing into the urogenital canal at the root of the penis. The vas deferens is homologous to the Wolffian canal. The vas deferens, before flowing into the urogenital canal, form paired compact bodies with a ribbed surface - seminal vesicles. They secrete a secretion that enters the liquid part of the sperm, and also prevents sperm from leaking out of the female’s genital tract, because has a sticky consistency.

At the base of the penis lies a paired prostate gland, the ducts of which flow into the initial part of the genitourinary canal. The secret is simple - this is the main liquid part of the sperm. Thus, sperm, or ejaculate, is the fluid secreted by the prostate, seminal vesicles, and the sperm themselves.

The urogenital canal runs on the underside of the copulatory organ. Up and to the sides of it lie cavernous bodies that have cavities. During sexual arousal, these cavities are filled with blood, which results in an enlarged penis. Many animals have a long bone between the corpora cavernosa, which provides strength to the penis.

In male females, the ovaries always lie in the body cavity. Paired oviducts, homologous to the Müllerian canal, open with their anterior ends into the body cavity. Here the oviducts form wide funnels. The upper part of the oviduct is convoluted - the fallopian tube. Next comes the expanded section of the uterus, which opens into the vagina (in most animals it is unpaired). The vagina passes into a short urogenital canal, where the urethra opens. On the ventral side of the urogenital canal there is a small outgrowth - the clitoris, similar to the male penis. Some species have a bone in the clitoris.

U different groups animals have different structures of the female reproductive tract. For example, in monotremes, the oviducts are paired and are divided only into the fallopian tubes and uterine horns, which open into the urogenital sinus with independent openings. In marsupials, the vagina is separate, but part of it remains paired. In placentals, the vagina is always unpaired, and the upper parts of the oviducts are paired. Rodents and some edentates have a double uterus (paired; its left and right sections open into the vagina with independent openings). In some rodents, bats, and predators, the uterus is bipartite, when its horns are connected only in the lower section. In carnivores, cetaceans, and ungulates, there is a two-horned uterus, when significant parts of the left and right horns of the uterus merge. In primates, prosimians and some bats, the uterus is simple - unpaired, and only the upper parts of the oviducts - the fallopian tubes - remain paired.

During embryogenesis, a baby's place (placenta) is formed in the uterus of mammals. In monotremes it is absent, in marsupials it is rudimentary. The placenta arises from the fusion of the outer wall of the allantois with the serosa. As a result, the chorion (spongy formation) is formed. The chorion forms outgrowths - villi. They grow together with loosened areas of the uterine epithelium. In these places, the blood vessels of the mother and fetus intertwine (without merging!). This creates a connection between the bloodstreams of the female and the embryo. This ensures gas exchange, nutrition, and removal of decay products from the embryo. In marsupials, the placenta is primitive; villi are not formed in the chorion (“yolk placenta”). In higher animals, the chorion always has villi. There are 3 types of placenta:

1) diffuse - villi are evenly distributed throughout the chorion (cetaceans, many ungulates, prosimians);

2) lobular - villi are collected in groups distributed over the entire surface of the chorion (ruminant);

3) discoidal - the villi are located on the disc-shaped portion of the chorion (insectivores, rodents, monkeys).

The total number of living mammals is more than 4000 species. In the class Mammals there are subclasses: Primal Beasts and Real Beasts.

Squad Predatory. Structural features, biology and practical significance.

The order unites terrestrial and semi-aquatic mammals, more or less adapted to feeding on animal food, some of them are omnivores (bear, badger). The main common feature is the structure of the dental system. The teeth are clearly differentiated into incisors, canines and molars. The incisors are small. The fangs are always well developed, large, conical, sharp. The molars are sharply tuberculate. There are so-called carnassial teeth - the last false root tooth of the upper jaw and the first true root tooth of the lower jaw. They are distinguished by their large size and strongly cutting edges. The collarbones are vestigial or absent. The forebrain is well developed, its cortex forms convolutions and grooves. Distributed throughout the land globe, excluding Antarctica. Lifestyle - single and family, mostly monogamous. They are active mainly at dusk and at night.

The canine family includes domestic dogs, wolves, jackals, foxes, and arctic foxes. These are medium-sized animals with long legs bearing non-retractable claws. All species are digitigrade, their limbs are adapted for long and fast running. The tail is long, usually densely pubescent. They lead (except during breeding times) a wandering lifestyle. They breed once a year - in spring. Many species are burrowers, others are denrs.

The cat family, in addition to the domestic cat, includes lions, tigers, leopards, lynxes, and various types of wild cats. Felines are medium and large animals with long digitally walking limbs armed with retractable claws. These are the most specialized predators for preying on live animals. They hunt, in most cases lying in wait and suddenly grabbing prey. The carnassial teeth are very developed. Distributed across all continents except Australia. The largest number of species is distributed in the tropics.

The mustelid family includes a large number of species: sables, martens, ermines, weasels, ferrets, minks, otters, badgers, etc. These are small and medium-sized predators with short plantigrade or semi-plantigrade limbs. The claws are not retractable, but sharp. Most are true predators, feeding mainly on mouse-like rodents, but there are also omnivorous species (badger). They have highly developed scent glands (especially ferrets). They breed in the spring. Only the badger hibernates.

The bear family unites large plantigrade animals with a very short tail. The claws are not retractable. Distributed mainly in the Northern Hemisphere. There are three species in Russia. Brown bear inhabits the forest belt of Russia, the mountains of the Caucasus and Central Asia. The food is mixed, in many places mainly plant-based. Spends the winter in shallow hibernation. Puppies in a den in winter. Polar bear inhabits the coast and islands of the North Arctic Ocean, hunts seals. It does not hibernate, but only pregnant females go to dens during the winter. The Himalayan (white-breasted) bear is relatively small in size, with black fur and a white spot on the chest. Lives in the Ussuri region. A semi-arboreal animal that feeds primarily on plant matter. In winter it hibernates, often in the hollows of large trees.

Many beasts of prey in Russia they are valuable fur-bearing animals, the trade of which produces high-quality furs (sable, marten, mink, ermine, fox, arctic fox). Some of them (silver-black fox, blue fox, sable, mink) are bred in fur farms. A number of species of predators (ferret, weasel, stoat) are useful in exterminating harmful rodents. Some species are carriers of the rabies virus.