Ecological groups of animals. Morphophysiological features. Morphophysiological and biocenotic features of the fox (vulpes vulpes L.) and corsac fox (vulpes corsac L.) and their significance in the circulation of natural focal infections and invasions in the south of Western Siberia

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 the Carnivores have adapted to living on all continents, except for the coldest - Antarctica. Let us briefly consider what information biology has collected about these animals to date.

Squad Carnivores

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

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

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

Predators are quite diverse and number about 240 species. Therefore, a number of families are distinguished in this detachment.

Wolf family

Describing the detachment Carnivores (mammals), they first of all mention the family, which got its name thanks to the tireless orderly of the forest. We are talking about the wolf and its relatives: the fox, jackal, arctic fox, raccoon and domestic dogs.

All of them are of medium size and 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 most powerful and 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 that can even attack a person. They are rightly considered to be eating a large amount of carrion.

But the fox can eat not only animal food. Her favorite delicacy is the sweet and juicy fruits of forest plants. Foxes live in pairs or whole families. A person especially appreciates the beautiful, warm and fluffy fur of these animals.

feline family

We continue to study the Carnivores order using the example of ... a domestic cat. What kind of predator is this? The real one! Its ancestor is a 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. Have you seen how a cat hunts a mouse? She does not catch up, but watches her prey. The same behavior is typical for larger cats: tiger, lynx, lion.

Most representatives of this family live in the tropical and subtropical climatic zone of our planet. And here is the owner of the taiga of the Far East. This is one of the largest 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 in the food chain, since tigers also prey on other predators, such as wolves.

Miracles of selection

Since the lion and tiger are the most prominent representatives of the entire planet, genetic scientists have tried to create their hybrids. This experiment ended quite successfully, since as a result of crossing, viable individuals were obtained, possessing new properties compared to the original forms. So, a liger is a hybrid of a lion and a tigress, capable of unlimited growth. In nature, this feature is characteristic of plants and fungi. Liger grows throughout life, sometimes reaching a length of up to 3 meters.

Usually interspecific hybrids are not able to produce fertile offspring. Tigrolev is an exception to this rule. This is practically the only case in the selection. Females obtained by crossing a tiger and a lioness are capable of procreation.

Cunya family

We continue to consider the order Predatory mammals on the example of a family that unites individuals with valuable fur. Otter, marten, ermine, mink, ferret - this is not a complete list of representatives of the Kunya family. Many of them are excellent tree climbers, and otters are excellent swimmers. Another representative of the marten is the badger. He especially appreciates meat, which is eaten, and fat, which has healing properties.

Bear family

Detachment Predatory has mastered all 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 mass can reach 750 kg. He is an excellent swimmer, hunting fish and pinnipeds.

But in the forests, the Predatory squad is represented by another beast - a brown bear. It can eat both plant and animal food, attacking deer or wild boars. In winter, this hibernates, and in summer it leads an active lifestyle. It is an object of hunting due to its valuable meat and skin.

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

Squad Predatory. Structural features, biology and practical significance.

The order unites terrestrial and semi-aquatic mammals, to some extent adapted to eating animal food, some of them are omnivorous (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. Fangs are always well developed, large, conical, sharp. The molars are sharp-tuberculate. There are so-called predatory teeth - the last false-rooted tooth of the upper jaw and the first true-rooted tooth of the lower jaw. They are distinguished by their large size and strongly cutting edges. The clavicles are rudimentary or absent. The forebrain is well developed, its cortex forms convolutions and furrows. Distributed throughout the world, excluding Antarctica. Lifestyle - single and family, mostly monogamous. They are active mainly at dusk and at night.

The dog family includes domestic dogs, wolves, jackals, foxes, 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 for the breeding season) a wandering lifestyle. They breed once a year - in spring. Many species are burrowers, others are loggerheads.

The cat family, in addition to the domestic cat, includes lions, tigers, leopards, lynxes, various types of wild cats. Cats are medium and large animals with long digitigrade limbs armed with retractable claws. These are the most specialized predators for acquiring live animals. They hunt, in most cases, stalking and suddenly grabbing prey. Predatory teeth are highly developed. Distributed on all continents except Australia. The largest number of species is distributed in the tropics.

The family of mustelids 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-stopigrade limbs. The nails are not retractable, but sharp. Most are real predators, feeding mainly on mouse-like rodents, but there are also omnivorous species (badger). They have highly developed odorous glands (especially ferrets). They breed in the spring. Only the badger hibernates.

The bear family unites large plantigrade animals with a very short tail. Claws are not retractable. They are distributed mainly in the Northern Hemisphere. There are three types in Russia. The brown bear inhabits the forest belt of Russia, the mountains of the Caucasus and Central Asia. The food is mixed, in many places mainly vegetable. Spends the winter in shallow hibernation. Puppies in the winter in a den. The polar bear inhabits the coast and islands of the Arctic Ocean, hunts seals. It does not hibernate, but only pregnant females lie in dens for the winter. The Himalayan (white-breasted) bear is relatively small in size, with a black coat color and a white spot on the chest. Lives in the Ussuri region. Semi-arboreal animal, feeding mainly on plant foods. In winter, it hibernates, often in the hollows of large trees.

Many predatory animals in Russia 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 predatory species (ferret, weasel, ermine) are useful in the extermination of harmful rodents. Some species are carriers of the rabies virus.

14.2.1 Skin

The skin of mammals has the following functions:

Limitation and protection of the body from the surface;

Participation in thermoregulation;

Participation in the expression of sexual dimorphism;

Involved in respiration and excretion.

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

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

The cutis, or skin proper, is made up of fibrous connective tissue, contains blood vessels, the bases of hair follicles, and sweat glands. In the lower part of the cutis, which is friable, fat is deposited. 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.

A hare has thin skin, so a predator can miss it by tearing off a piece of skin.

Not all animals have hair. Dolphins and whales don't have it. In pinnipeds, the hairline is reduced.

The structure of the hair is as follows. The 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 tissue that provides low thermal conductivity of the hair. The cortical layer is dense and gives strength to the hair. The skin is thin, protects the hair from mechanical and chemical influences. The upper part of the root is cylindrical, while the lower part expands into a bulb that encloses the hair papilla. The papilla contains blood vessels. The lower part of the hair sits in the hair bag, where the ducts of the sebaceous glands open.

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

In most species, the basis of the coat is dense low fluff (undercoat). Underground animals (mole, mole rat) have no guard hairs. In adult deer, wild boars, and seals, the undercoat is reduced (the cover consists mainly of the awn).

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

Vibrissae are very long, stiff 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 tree forms, on the belly (squirrel). At the base of the hair follicle and in its walls 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. Available on the paws of many mouse-like rodents, 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 expanded. Fast-running large mammals have hooves. At the same time, in species walking in swamps, the hooves are wider and flatter. Steppe and mountain species (antelopes, rams 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 substance, they develop from cutis.

Skin glands are of 4 types. Sweat - open on the surface of the skin, emit 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, lizards; rodents have only on their paws, in the groin and on the lips. There are very few sweat glands in dogs and cats. The sebaceous glands open into the funnel of the hair follicle. Their secret - lard - lubricates the hair and epidermis of the skin. Odorous - modified sweat or sebaceous glands, and sometimes a combination of them. The anal glands of mustelids have a very strong odor, especially in skunks, or American stinkers. It is believed that these glands are important during the rut, because. stimulate sexual arousal. Milky - modified sweat glands. In echidnas, the glandular field is located in the bag for carrying eggs and young, in the platypus, the glandular field is located directly on the belly, in marsupial and placental ducts of the mammary glands open on the nipples.

In mammals, the skin and its derivatives provide mechanisms for physical thermoregulation by regulating heat transfer. With the expansion of skin vessels, heat transfer increases sharply, with narrowing, it decreases. Cooling of the body also occurs when water evaporates from the surface of the skin, secreted by the sweat glands.

The density and height of the hairline 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 secret of the skin glands, like other smelling secretions, is an important means of intraspecific communication. The signal is transmitted over long distances and stored for a long time. Families of animals often mark the territory, while the mark is also left on the cubs, so they are easy to find and distinguish.

Odor signaling is crucial for the development of mammalian behaviors.

14.2.2 The muscular system of mammals

Contains many diversely located muscles. The presence of a thoracic-abdominal barrier is characteristic - the dome-shaped muscle of the diaphragm, which is of great importance for the implementation of the act of breathing. The subcutaneous musculature, which sets the skin in motion, is well developed. In hedgehogs, it provides the ability to roll into a ball. "Bristling" (for example, when frightened) is also associated with this muscle. On the face, such muscles are mimic (well developed in primates).

3. Mammalian Skeleton

The characteristic features in the structure of the skeleton of mammals are as follows. The vertebrae are platycoelous (they have flat articular surfaces). Between the vertebrae are cartilage discs (menisci).

The spine is divided into cervical, thoracic, lumbar, sacral and caudal regions. The number of cervical vertebrae is constant - 7, cervical vertebrae 1 and 2 are well expressed - 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 the bottlenose whale have 9, and some sloths have 24).

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

The skull has a fairly large braincase, and it is fairly well developed compared to the front of the skull. The number of individual bones in the skull is less than in the lower groups of vertebrates, because the bones fuse into complexes (for example, the ear bones fuse into a single stony bone. The sutures between the bone complexes overgrow rather late, which contributes to an increase in the volume of the brain as the animal grows. In the occipital region, a single occipital bone with two condyles for connection with the atlas. In the facial in the skull, the zygomatic arch characteristic of mammals is formed from the zygomatic processes and zygomatic bones.The development of a secondary bone palate (from the palatine processes of the premaxillary and maxillary bones and palatine bones) is characteristic, therefore, the choanae open behind the palatine bones, and breathing is not interrupted at the moment of chewing the food lump. In the inner ear there are 3 auditory ossicles: the hammer, anvil and stirrup.

The shoulder girdle contains a scapula and a rudimentary coracoid at its base. The clavicle is only in mammals, the forelimbs of which perform various complex movements (monkeys).

The pelvic girdle consists of 3 paired bones: ilium, ischium and pubis. In many species, these bones are fused into one innominate bone.

The skeleton of paired limbs retains all the main structural features of a typical five-fingered limb. At the same time, in terrestrial forms, the proximal sections are elongated: the thigh and lower leg. In aquatic animals, these sections are shortened, and the distal ones (metacarpus, metatarsus, phalanges of fingers) are elongated. In fast running tarsus, metatarsus, wrist and metacarpus are located almost vertically (dog); in the most advanced runners (ungulates), the first finger atrophies, and one third finger (equids) or 3rd and 4th fingers (artiodactyls) receive predominant development.

3. Digestive organs of mammals

The digestive tract in 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 as a temporary food reserve. There are no fleshy lips in monotremes and cetaceans. There are 4 pairs of salivary glands in the oral cavity, where food is mechanically crushed and chemically processed. The salivary glands in ruminants are especially developed (up to 56 liters of saliva are secreted in a cow 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. Teeth are thecodont (sitting in the cells of the jaws), the dental system is diphyodont (teeth change once in a lifetime). The tongue is muscular, serves for grasping food, lapping water, turning food over in the mouth.

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

The esophagus is well expressed, contains smooth muscles, in ruminants - and striated, and this allows you to burp food.

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

The intestine is divided into thin, thick and straight sections. In species that eat coarse plant food, on the border of the thin and thick sections, there is a long and wide caecum (in some animals - hares, semi-monkeys - it ends with a vermiform appendix). Vegetable food roams in the caecum. 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 the watering place. Others get enough water in juicy food. There are those who never drink and eat very dry food (desert rodents). They are supplied with metabolic water. When used for 1 day 1kg. 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 of the 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 are paired arytenoid cartilages, the epiglottis is adjacent to the anterior edge of the thyroid cartilage. Between the cricoid and thyroid cartilages are small saccular cavities - the ventricles of the larynx. The vocal cords lie between the thyroid and arytenoid cartilages.

The trachea and bronchi are well developed. The smallest branches of the bronchi - bronchioles - end in alveoli. Blood vessels branch in the alveoli. A huge number of alveoli forms a large surface for gas exchange. The exchange of air in the lungs is due to 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 higher the NPV). Ventilation of the lungs not only determines gas exchange, but is also important for thermoregulation (especially for species with underdeveloped sweat glands. Their body cooling occurs with the help of a polyp when water vapor is exhaled with air.

14.2.6 Mammalian circulatory system

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

The cardiac index (the relative mass of the heart, expressed as a percentage of the total body weight) in the sperm whale is 0.3, and in the common shrew it is 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 mm Hg, in a dog it is 112/56.

The total amount of blood in mammals is greater than in lower vertebrate groups, and the oxygen capacity of the blood is higher, because. it has 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 down blood flow, and blood oxygen is used more fully. In animals immersed in water for a long time, peripheral blood circulation is turned off, 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 the cerebellum is increased (due to the growth of the roof of the forebrain). Because in mammals, the cerebral cortex is developed, their gray matter is located on top of the white. The centers of higher nervous activity are located in the cerebral cortex. The complex behavior of animals is associated with the progressive development of the cerebral cortex. The cerebral cortex is connected by a commissure of white nerve fibers - the corpus callosum. The cerebral cortex in most mammals is powerful and consists of 7 layers, covered with furrows and convolutions. The diencephalon is covered from above by the cerebral hemispheres. The pineal, pituitary and hypothalamus are small, but they perform very important functions. The midbrain is subdivided into 4 tubercles. The cerebellum is large and divided into several sections (this is due to the very complex nature of movements in animals). In the medulla oblongata are the nuclei of the centers of respiration, circulation, digestion and other important reflexes.

14.2.8 Mammalian sense organs

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

The organs of hearing are also very well developed in animals. If the lower classes have developed the inner and middle ear, then mammals have developed two more new departments: the external auditory meatus and the auricle. . The auricle significantly enhances the subtlety of hearing, it is especially well developed in nocturnal animals, in forest ungulates, desert dogs. There is no auricle in water and underground animals (whales, most pinnipeds, mole rats). The ear canal is separated from the middle ear by the tympanic membrane. There are 3 auditory ossicles in the middle ear (instead of 1, as in amphibians, reptiles and birds). The hammer, anvil and stirrup are movably connected, the stirrup rests against the oval window of the membranous labyrinth of the inner ear. This ensures a 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 in the life of mammals are not as important as in the life of birds. Animals pay little attention to motionless objects. Forest animals have less sharp eyesight than open landscape animals 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 less developed than in birds. Almost the entire spectrum is distinguished only by the higher apes of the Eastern Hemisphere. And in the forest polecat, for example, color vision was not found at all.

A characteristic feature of the organs of touch in mammals is the presence of vibrissae (tactile hair).

14.2.9 Mammalian excretory system

The kidneys in mammals are pelvic - metanephric. Trunk buds are embryonic, but later reduced. The kidneys of animals are bean-shaped or lobed, with a smooth or tuberculate surface, in some species they are divided into lobes by intercepts. The outer layer of the kidney - cortical - contains convoluted tubules, beginning with Bowman's capsules, inside which are Malpighian bodies (tangles of blood vessels). Filtration occurs in the tangles, 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 occurs from the primary urine, water, sugar and amino acids. This is how secondary or final urine is formed. The smaller the animal, the greater 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 a placenta, through which the developing embryo can receive unlimited amounts of water from the mother's blood. Through the placenta, toxic products of protein metabolism can be excreted indefinitely from the embryo. Urea is much more toxic than uric acid, but this type of metabolism requires a very large amount of water to excrete urine. This is also evidence of the proximity of mammals to amphibians.

In the medulla of the kidneys there are direct 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 in this way.

14.2.10 Mammalian reproductive system

The gonads of the male are called testes and are oval in shape. In most animals (except monotremes, some insectivores, edentulous, elephants, cetaceans) they are initially located in the body cavity, and descend as they mature. Through the inguinal canals into the scrotum. An appendage is adjacent to the testis - a tangle of convoluted seminiferous tubules of the testis. The appendage is homologous to the anterior part of the trunk kidney. The vas deferens departs from the appendage, flowing at the root of the penis into the urogenital canal. The vas deferens is homologous to the Wolffian duct. The seminal ducts, before falling into the urogenital canal, form paired compact bodies with a ribbed surface - the seminal vesicles. They secrete a secret that enters the liquid part of the sperm, and also prevents the sperm from flowing out of the female genital tract, because. has a sticky texture.

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

On the underside of the copulatory organ passes the urogenital canal. Above and on the sides of it lie cavernous bodies that have cavities. These cavities fill with blood during sexual arousal, which results in an increase in the penis. Many animals have a long bone between the cavernous bodies, which provides the strength of the penis.

In male females, the ovaries always lie in the body cavity. The paired oviducts, homologous to the Müllerian canal, open with their anterior ends into the body cavity. Here the oviducts form wide funnels. The upper section 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 also 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.

Different groups of animals have a different structure of the female genital tract. For example, in monotremes, the oviducts are paired and are divided only into the fallopian tubes and uterine horns, which open with independent openings into the urogenital sinus. In marsupials, the vagina is isolated, but part of it remains paired. In placental, the vagina is always unpaired, and the upper sections of the oviducts are paired. In rodents and some edentulous ones, there is a double uterus (steam room; its left and right sections open into the vagina with independent openings). In some rodents, bats, predators, the uterus is bifid, when its horns are connected only in the lower section. Carnivores, cetaceans, and ungulates have a bicornuate uterus, when significant parts of the left and right uterine horns merge. In primates, semi-monkeys and some bats, the uterus is simple - unpaired, and only the upper sections of the oviducts - the fallopian tubes - remain paired.

During embryogenesis, a baby place (placenta) is formed in the uterus of mammals. In monotremes, it is absent, in marsupials - rudiments. The placenta arises from the fusion of the outer wall of the allantois with the serosa. As a result, a chorion (spongy formation) is formed. 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!) So there is a connection between the blood channels of the female and the embryo. This ensures gas exchange, nutrition, removal of decay products from the embryo. In marsupials, the placenta is primitive, villi are not formed in the chorion (“yolk placenta”). In higher chorions, the chorion always has villi. There are 3 types of placenta:

1) diffuse - the villi are evenly distributed over the chorion (cetaceans, many ungulates, semi-monkeys);

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

3) discoidal - the villi are located on the discoid section of the chorion (insectivores, rodents, monkeys).

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

1.1.1. Anatomical features of the structure of the skeleton

In predatory fur-bearing animals, the skull is flat and elongated in length, the cranium is small. The jaw is rigidly attached to the jaw joint by roller-shaped articular processes. Its displacement to the side, movement forward and backward is impossible, which leads to a reliable grip with jaw pliers. The upper jaw is somewhat pushed forward, due to which, during closing, the teeth of the upper jaw slide over the teeth of the lower jaw and cut meat like scissors. In nutria, the skull is small with a developed facial skull. Gnawing teeth are large, orange in color, strongly advanced forward. Fur-bearing animals (except nutria) are characterized by the change of milk teeth to permanent ones.

The spinal column in fur-bearing animals, as in domestic animals, is divided into: cervical, thoracic, lumbar, sacral and caudal. All animals have 7 cervical vertebrae; Arctic foxes, foxes and nutrias have 13; in minks, ferrets (furo, ferret, thorefrette or thorzofret) and sables - 14 thoracic vertebrae.

The lumbar region is represented by 6 ... 7 vertebrae, the sacrum is formed by three fused bones (ilium, ischium and pubis).

In the caudal region, foxes, arctic foxes, ferrets and minks have 20 ... 23 vertebrae; sables have 15...16; nutria have 25 vertebrae.

The chest in 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 false pairs); 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), carpus, metacarpus and phalanges of the fingers. Nutria also have a clavicle, connected on one side to the scapula, and on the other, to the first rib.

The pelvic girdle consists of the sacrum, femur, lower leg bones (tibia and tibia), tarsus, metatarsus and phalanges of the fingers.

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

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

1.1.2. Peculiarities of digestion in fur-bearing animals

In their natural habitat, fur-bearing animals of the order of carnivores feed mainly on animal feed, which has 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 serve to grind food. The molars have sharp, serrated edges and serve to grab food and tear it into pieces. In the canine family, the raccoon dog is an exception. It is omnivorous, has small fangs, underdeveloped upper teeth, the surface of the lower molars is smoothed.

A different structure has a dental system in rodents - nutria, muskrats, chinchillas - herbivorous animals. Their incisors are devoid of roots and grow continuously throughout their lives. Only one pair of incisors is located in the upper jaw, fangs are absent, 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 the food is almost not chewed, but 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. In nutria, the stomach is of a simple digestive type, the caecum reaches 40-45 cm.

The intestines of carnivores are much shorter than those of herbivores. The small length of the intestines in carnivores causes 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, a very underdeveloped caecum - 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 leads to a constant deficiency of B vitamins.

Of the nutrients, carbohydrates are digested worse than protein and fat (in minks and ferrets, this digestibility is slightly lower than in arctic foxes and foxes, and in the latter it is lower than in rodents). Predatory fur animals practically do not digest fiber of vegetable feed, 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 bred in captivity willingly eat a variety of 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, regulates the reproduction of microorganisms, and is directly involved in digestion.

1.1.3. Features of the growth and development of fur animals

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

– limited breeding season;

- at certain times, the molting of the hairline passes;

- there are seasonal changes in metabolism.

An important biological feature of fur-bearing animals is their high growth rate in the first months of life. In the growth of young animals, certain stages are observed that have a great influence on the development of the organism and the formation of productive qualities. An example is the effect of inhibition of the 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 the reproductive qualities of animals. Puppies of predatory fur animals are born helpless. They are blind, with a closed ear canal, without teeth, with a very short, sparse hairline, but they develop rapidly.

The mass 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 mass of an adult animal. The teeth of mink and ferret puppies erupt at 16-20 days of age. The transition of puppies to an independent type of nutrition after jigging 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 its seasonal fluctuations are noted.

Puppies of foxes and arctic foxes grow somewhat more slowly (at birth they weigh 80 ... 100 grams). By the age of 20 days, the mass of arctic foxes increases by 7.5 times; by the time of jigging, they accumulate almost a fifth, and by the age of 4 months - 80% of the mass of adult animals. In the first days of life, their limbs grow most intensively, then the head and, finally, the trunk. By the age of 5-6 months, fox puppies and foxes acquire body proportions of adult animals. The change of milk teeth to 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 until one and a half years. Nutria breed throughout the year.

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

Cage sables have a parabolic type of growth (intensive growth occurs up to 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 ear canals of minks, ferrets and sables open in the last week of the first month of life. The growth of young animals is most intensive in the first months of life, so the feeding conditions should not constrain the potential development of animals. Growth retardation is often not compensated, which affects the breeding performance of animals and the size of their skins.

1.1.4. Seasonal changes in metabolism

The intensity of metabolism and energy in animals in different seasons of the year is different. Despite domestication, they have retained the adaptive reactions that have developed in the process of evolutionary development to changing natural food conditions over the seasons. There is a certain relationship between seasonal fluctuations in energy metabolism in predatory animals with food conditions. Thus, a decrease in the intensity of metabolism in the autumn months with an abundance of food in nature ensured the accumulation of reserve fat and other nutrients in the body for use in winter and the best development of winter pubescence. A further decrease in metabolism in the winter months, when food conditions worsened, was determined by the need to reduce the body's need for nutrition at this time. The construction of feeding in accordance with these prevailing fluctuations in metabolism - increasing the fatness of animals in autumn, and reducing their live weight in the winter months - has, as practice has shown, important for ensuring normal reproduction and obtaining good quality skins. In the summer months, the metabolism is most intense, in autumn it decreases, the lowest in winter, and in the spring it rises again. 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 largest. Seasonal changes in fat deposition reflect the features of thermoregulation in fur-bearing animals. The accumulation of fat by them by winter makes it possible to reduce heat transfer, and, consequently, energy consumption in the cold season; a decrease in the amount of fat in the summer and a more rare hairline 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 nutria, the metabolism almost does not change according to the seasons of the year (with the same feeding, their live weight in summer is about 10% higher than in winter, i.e. in metabolism, they retain the characteristics of animals of the southern hemisphere - the birthplace of nutria - South America).

1.1.5. Hair shedding in animals

The molting of the hairline in animals takes place twice a year - in the spring the winter pubescence falls and the summer grows, in the fall the summer is again replaced by winter. The winter hair falls out and is replaced by a short dark one; in July, the short hair completely covers the animal. 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 to the greatest extent regulated by the duration of daylight hours, the most constant of the external stimuli. By artificially changing the length of daylight hours, it is possible to slightly shift the natural timing of the maturation of the reproductive system, the duration of pregnancy.

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

Ecological groups of amphibians. Morphophysiological features.

Evolution of methods of reproduction of vertebrates.

In the evolution of vertebrates - from fish to warm-blooded ones - there is a tendency to reduce the number of offspring and increase 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 the stages of individual development (ontogenesis), namely:

embryonic development;

asexual (from birth to puberty);

sexually mature;

aging.

Embryonic development begins with the fertilization of the egg, its further fragmentation with the formation of a blastula (consists of one row of cells), which, developing, forms the germ layers - the gastrula, tissues and organs of an adult individual are formed from the germ layers. The process of tissue formation is called histogenesis, and the process of organ formation is called organogenesis. Embryonic development ends with the formation of the 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 organisms 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 such a process as regeneration - the renewal of lost or damaged organs, as well as the renewal of the 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, a tail can be updated, 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 land mammals:

1. Have a short body, weak legs.

2. They have a proportionally folded body, a developed neck.

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

4. Represented mainly by predators.

2. Underground mammals:

1. Have a short body, valky, short fur, thick, lint-free, growth direction.

2. The auricles and vision are well developed.

3. Representatives are foxes, hares, badgers.

3. Aquatic mammals have:

1. Fish-shaped body, no neck, horizontal tail fin.

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

3. Limbs that turned into fins.

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