Mammals that live in the aquatic environment. Lifestyle of some mammals. The most dangerous animals of the oceans

COMMUNICATION OF AQUATIC MAMMALS

Sounds are like signals. have ears consisting of an external opening, a middle ear with three auditory ossicles and an inner ear connected by the auditory nerve to the brain. Marine mammals have excellent hearing, which is also helped by the high sound conductivity of water.

Seals are among the noisiest aquatic mammals. During the breeding season, females and young seals howl and moo, and these sounds are often drowned out by the barks and roars of males. Males roar primarily to mark territory, in which they each gather a harem of 10–100 females. Vocal communication in females is not so intense and is associated primarily with mating and caring for offspring.

Whales constantly make sounds such as clicking, creaking, low-pitched sighs, as well as something like the creaking of rusty hinges and muffled thuds. It is believed that many of these sounds are nothing more than echolocation, used to detect food and navigate underwater. They can also be a means of maintaining group integrity.

Among aquatic mammals, the undisputed champion in emitting sound signals is the bottlenose dolphin (Tursiops truncatus). The sounds made by dolphins are described as moaning, squeaking, whining, whistling, barking, squealing, meowing, creaking, clicking, chirping, grunting, shrill screams, as well as resembling the noise of a motor boat, the creaking of rusty hinges, etc. These sounds consist of a continuous series of vibrations at frequencies ranging from 3,000 to more than 200,000 hertz. They are produced by blowing air through the nasal passage and two valve-like structures inside the blowhole. Sounds are modified by increasing and decreasing tension in the nasal valves and by the movement of "reeds" or "plugs" located within the airways and blowhole. The sound produced by dolphins, similar to the creaking of rusty hinges, is “sonar,” a kind of echolocation mechanism. By constantly sending these sounds and receiving their reflections from underwater rocks, fish and other objects, dolphins can easily move even in complete darkness and find fish.

Dolphins undoubtedly communicate with each other. When a dolphin makes a short, sad whistle, followed by a high-pitched, melodic whistle, it is a distress signal, and other dolphins will immediately swim to the rescue. The cub always responds to the mother's whistle addressed to him. When angry, dolphins "bark" and the yapping sound, made only by males, is believed to attract females.

Visual signals. Visual signals are not essential in the communication of aquatic mammals. In general, their vision is not sharp and is also hampered by the low transparency of ocean water. One example of visual communication worth mentioning is that the hooded seal has an inflating muscular pouch above its head and snout. When threatened, the seal quickly inflates the pouch, which turns bright red. This is accompanied by a deafening roar, and the trespasser (if it is not a person) usually retreats.

Some aquatic mammals, especially those that spend part of their time on land, perform demonstrative actions related to the defense of territory and reproduction. With these few exceptions, visual communication is poorly used.

Olfactory and tactile signals. Olfactory signals probably do not play a major role in the communication of aquatic mammals, serving only for mutual recognition of parents and young in those species that spend a significant part of their lives on rookeries, for example, seals. Whales and dolphins appear to have a keen sense of taste, which helps them determine whether a fish they catch is worth eating.

In aquatic mammals, tactile organs are distributed throughout the skin, and the sense of touch, especially important during periods of courtship and caring for offspring, is well developed. Thus, during the mating season, a pair of sea lions often sits facing each other, intertwining their necks and caressing each other for hours.

Thanks to their warm-blooded nature and high level of organization, mammals have spread across the Earth from the tropics to high latitudes. Depending on the habitat animals are divided into several ecological groups:

• land animals,
• underground mammals,
• aquatic Mammals,
• flying mammals.

Each group includes small groups. So, among there are groups of terrestrial mammals that lead:

• typically terrestrial
• woody,
• tree climbing or other way of life.

Land animals - the most numerous group in terms of the number of species, which is divided into two subgroups:

• forest animals,
• animals of open spaces.

For animals inhabiting the forest and leading a terrestrial lifestyle (elk, deer, roe deer, wolverine, brown bear), is characteristic limited vision, well-developed hearing and sense of smell. They get all their food on the ground. Babies are born on the forest floor (elk, roe deer), in burrows (badger), in dens (brown bear).

Arboreal mammals(squirrels, flying squirrels, some species of martens, most monkeys) spend most of their lives in trees, where they get food, make nests, and hide from enemies. They are characterized elongated slender body and very mobile limbs. There are often special adaptations for climbing trees:

• sharp curved claws,
• hapal type paws with well-developed toes,
• prehensile tail, etc.

Animals leading a terrestrial lifestyle (sable, chipmunk) feed mainly on the ground, and make nests under the roots of trees, in hollows located not high from the ground, in fallen trees.

TO land animals open spaces include ungulates, lagomorphs, some carnivores, etc. They are characterized by:

• slim body,
• ability to run fast,
• protective body coloring,
• well developed vision,
• have hooves or thick, blunt claws.

In large herbivorous animals (antelope, camels, horses), newborn babies immediately get to their feet and move behind their parents. Small animals (gophers, marmots, hamsters), although they spend a significant part of their time on the surface of the earth, where they find food, live in burrows, serve as a place of rest, feeding their offspring, and summer and winter hibernation. They have flattened body, short legs with large but blunt claws; the fur is short and rough.

Terrestrial animals that are common in various habitats. Some species of animals, for example, the wolf and the fox, live both in forests and in steppes, deserts, and mountains. The nature of their food, methods of obtaining, and breeding conditions are different and associated with specific places of residence. So, wolves that live in forests give birth to babies in dens, and sometimes dig holes in the desert and tundra.

Underground Beasts (moles, mole rats, blind men, armadillos) spend their entire life (or most of it) in the soil, finding shelter and food there. Their body is flattened; the neck is weakly defined, thick, legs and tail are short. The hairline is short, often without lint. The eyes are reduced to one degree or another. There are no auricles. Some dig the ground with their forelimbs, others loosen with their incisors.

Aquatic mammals They spend their entire life (or most of it) in an aquatic environment. Cetaceans and sirenians lead an exclusively aquatic lifestyle. Their hair completely disappears, and the layer of subcutaneous fat is well developed. There are no hind limbs. The organ of movement is the caudal fin. Pinnipeds lead a predominantly aquatic lifestyle - only reproduction and molting occur outside the water. The hair cover of pinnipeds is reduced to one degree or another and the function of thermal insulation is performed by a layer of subcutaneous fat. With the help of their hind limbs (flippers), moved far back, they swim and dive.

Half aquatic Mammals live both in water and on land (otter, nutria, beaver, muskrat, muskrat). Their limbs are short, there is a swimming membrane between the toes of the hind legs; the tail of some is flat, covered with scales and is used as a rudder when swimming; the auricles are shortened or completely reduced, the ear openings and nostrils are closed with valves when animals are immersed in water; the hair is thick, slightly wetted by water.

Flying animals are a highly specialized group, whose representatives have adapted to flight (the Chiroptera series). In connection with the flight they developed keel, as well as muscles that move the wings; the bones of the skull have fused, the chest has become stronger.

The streamlined, often torpedo-shaped body gives them an external resemblance to fish. However, cetaceans are warm-blooded, breathe atmospheric air, bear a fetus in the uterus, give birth to a fully developed calf capable of independent existence, which the mother feeds with milk, and the remains of hair are visible on their body. According to these and some other characteristics, they are similar to other mammals, and the general plan of their structure also indicates that they belong to this class animals .

The body of cetaceans, round in cross-section, tapers towards the end and ends with a pair of wide caudal fins, flattened in the horizontal plane. These fins, although devoid of a bony skeleton (there is cartilaginous supporting tissue inside them), serve as the main organ that ensures the animal’s forward movement. The pectoral fins, or flippers, correspond to the forelimbs of land mammals; their carpal parts are not dissected externally, and sometimes are fused internally, forming spade-shaped structures. They serve as stabilizers, “depth rudders,” and also provide turning and braking. There are no hind limbs, although rudiments of pelvic bones have been found in some species. The neck is very short, since the seven cervical vertebrae common to mammals are greatly shortened and fused into one or more plates, the total length of which does not exceed 15 cm.

The body of cetaceans is covered with smooth, shiny skin, which makes it easier to glide in the water. Under the skin there is a layer of adipose tissue (blubum) ranging from 2.5 to 30 cm thick. Fat protects the body from hypothermia and helps retain water in the body that would otherwise diffuse into the environment; body temperature is maintained at approximately 35? C. Animals do not need fur since the fat provides sufficient thermal insulation, but sparse hair can be found on the snout during embryonic stages and in adults.

The head is very large and wide. The neck is so shortened that outwardly the boundary between the head and the body is not noticeable. There are no external ears, but there is an auditory canal, which opens through a small hole in the skin and leads to the eardrum. The eyes are very small, adapted to life in the sea. They are able to withstand high pressure when the animal is immersed to great depths; large, fatty tears are released from the tear ducts, which help to see more clearly in the water and protect the eyes from the effects of salt. Nostrils - one (in toothed whales) or two (in baleen whales) - are located in the upper part of the head and form the so-called. blowhole. In cetaceans, unlike other mammals, the lungs are not connected to the oral cavity.

The animal inhales air, rising to the surface of the water. Its blood is capable of absorbing more oxygen than that of land mammals. Before diving into the water, the lungs are filled with air, which, while the whale remains under water, is heated and saturated with moisture. When the animal floats to the surface, the air it exhales forcefully, in contact with the cold outside, forms a column of condensed steam - the so-called. fountain. Thus, whale fountains are not columns of water at all. In different species they are not the same in shape and height; for example, the fountain at the top of the southern right whale splits into two. The exhaled air is forced through the blowhole under such strong pressure that it produces a loud trumpeting sound, which in calm weather can be heard from a great distance. The blowhole is equipped with valves that close tightly when the animal is immersed in water and open when it ascends to the surface.

The cetacean order is divided into two suborders: toothed whales (Odontoceti) and baleen whales (Mysticeti). The former are considered less specialized; These include, in particular, beaked whales, sperm whales, killer whales, as well as smaller forms - dolphins and porpoises. Sperm whales reach a length of 18 m and a mass of 60 tons; the length of their lower jaw reaches 5-6 m.

The teeth of baleen whales are replaced by long, fringed horny plates (baleen) that hang from the upper jaw and form a filter for straining small crustaceans and fish from the water. This suborder includes minke whales, as well as blue, humpback, dwarf, smooth, bowhead and other whales. Some blue whales reach a length of 30 m. This animal is larger than even giant dinosaurs. It can weigh as much as 150 bulls or 25 elephants.

Fossils of primitive whales, zeuglodonts ("jugular-toothed"), have been found in marine sediments of Africa, Europe, New Zealand, Antarctica and North America. Some of them were giants more than 20 m long.

A whale can reach enormous sizes, since its limbs do not have to support its body weight: in the water it is as if weightless. A large whale swimming at a speed of 20 knots (37 km/h) “generates” energy of 520 hp. With.

Whales swallow food whole and consume up to a ton of food per day. The sperm whale's pharynx is very wide, so that it can easily swallow a person, but in baleen whales it is much narrower and only allows small fish to pass through. The sperm whale feeds mainly on squid and often feeds at depths of more than 1.5 km, where pressure exceeds 100 kg/cm2. The killer whale is the only representative of the order that regularly eats not only fish and invertebrates, but also warm-blooded animals - birds, seals and whales. Cetaceans have a very long intestine and a complex multi-chambered stomach, consisting, for example, of 14 sections in beaked whales, and 4 in right whales.

The female gives birth to one baby underwater. It comes out of her body tail first. The cub is fully developed and is almost immediately able to follow the herd. It suckles for approximately 6 months and grows rapidly, reaching sexual maturity by age three, although increasing in size continues until age 12. Most large whales breed once every two years. Despite their enormous size, these animals are not very durable. Science knows very few specimens of right whales older than 20 years.

Herds of whales can commit something akin to mass suicide. Sometimes a hundred or more of their individuals wash ashore at the same time. Even if the suffocating animals are towed back to sea, they return to land. The reasons for this behavior have not yet been determined.

Whales provide humans with many useful products. People have been hunting them since ancient times, and whaling existed before the 10th century. In addition to meat, whale oil (blub), which is used to make soap and cosmetic creams, is of great value.

Ambergris is extracted from the intestines of sperm whales; this grayish substance is secreted there as a result of irritation of the mucous membrane caused by the horny jaws of swallowed squids. Pieces of ambergris weigh up to 13 kg, and the mass of its largest “nugget” is 122 kg. It contains sodium chloride, calcium phosphate, alkaloids, acids and the so-called ambrine; this substance is lighter than fresh and salt water, softens in the hands, melts at a temperature below 100? , and with stronger heating it evaporates. Ambergris was once highly valued as a perfume fixative. Currently, whaling is almost universally prohibited, since as a result of irrational mining, the whale population has greatly decreased and some of their species have found themselves on the brink of extinction. extinction. International agreements allow the capture and slaughter of individual specimens for scientific research. In addition, some peoples, such as the Eskimos, for whom whale hunting is one of the most important traditional activities, are allowed to continue it on a limited scale.

Mammals are not the most numerous class of animals, but they are our closest relatives on the planet. Man also belongs to the class of mammals. Mammals are distinguished by high intelligence, complex behavior, and the ability to learn.

The living nature of the Earth is divided into five kingdoms: bacteria, protozoa, fungi, plants and animals.

What all mammals have in common is that they feed their young with milk. The class of mammals is divided into subclasses: oviparous and viviparous.

Despite all the diversity of forms, mammals have a number of common characteristics. All mammals are dioecious, that is, there are male and female individuals: males and females.

After the male fertilizes the saka, the female becomes pregnant. The period ranges from 12 days to more than 600 days. Newborns depend on their mother for quite a long time and need her milk.

Most mammals take care of their offspring and teach their young all the intricacies of independent life. The lifespan of mammals ranges from 1 year to 70 years.

The first mammals appeared on Earth about 200 million years ago, separating from animal-like reptiles. The historical path of development of the animal world is called evolution. During evolution, natural selection occurred - only those animals survived that were able to adapt to environmental conditions. Mammals have evolved in different directions, forming many species. It happened that animals that had a common ancestor at some stage began to live in different conditions and acquired different skills in the struggle for survival.

Most mammals are characterized by a constant body temperature, independent of the environment (except for the period of hibernation). Mammals can be divided into herbivores - eating vegetation, carnivores - eating the meat of other animals and insects, and omnivores - consuming a wide variety of foods.

The ability to adapt to a wide variety of living conditions has allowed mammals to spread throughout the globe and occupy a variety of habitats.

All mammals are warm-blooded animals. They have a relatively large brain, sweat glands in the skin and hair or fur. Most mammals are four-legged.

Mammals usually have well-developed senses of vision, hearing, smell, taste and touch. This helps them get food, avoid encounters with predators, and find a mate. The sense organs are most often located in the head, near the brain.

Mammals are terrestrial and arboreal, underground and aquatic. Some species have even adapted to flight.

Nevertheless, each species of animal occupies a certain part of the earth's surface, within which it undergoes its full development cycle. This territory is called the range.

Animals - big and small, those we consider useful to us, and those we call pests - they all have the right to live on our planet. More than one animal species has disappeared from the face of the Earth through human veins. Our duty is to preserve what remains.

By planting trees, feeding birds in winter, releasing a caught butterfly or beetle, we contribute to the great cause of nature conservation.

The platypus spends most of the day in a hole that it digs not far from the river. At dawn and dusk he goes outside. The platypus scrapes mud with its sensitive beak and searches for insects, worms, larvae, crustaceans and frogs. Its beak is actually the animal's muzzle, covered with skin rich in nerve endings. Platypuses and echidnas are venom-bearing mammals. They have a bone spur on their hind legs, along which poisonous liquid flows.

The echidna's body is covered with spines to protect itself from enemies. When threatened with attack, it curls up into a ball or quickly buries itself in the ground. Only its needles remain outside. This way it protects the soft belly and muzzle not covered with needles. The echidna lives on the ground and feeds on insects, mainly ants and termites. At the age of 50 days, the small echidna already leaves the pouch, but lives in the hole for about 5 months.

BALL BOARDERS

Ball armadillos are one of the rarest and are listed in the Red Book. These amazing animals can curl up into an unusually dense ball, tightly protected on all sides by armor. Neither a fox nor a wolf can break through such reliable protection. Armadillos can have from 8 to 100 teeth, which grow throughout their lives. Moreover, even two individuals of the same species can have a completely different number of teeth.

The GIANT PANDA is perhaps the most adorable of all bears and one of the rarest animals on Earth. Giant pandas live in China, in mountain forests, at an altitude of 2000 - 3000 m, where bamboo thickets form undergrowth. Bamboo is a low-nutrient food, so pandas eat it in large quantities, spending 15 hours a day on food, eating up to 20 kg of bamboo. The soles and base of each panda toe have well-developed hairless pads that help hold the smooth stem of the bamboo. Unfortunately, there are currently only about 1,000 giant pandas left in the wild. Pandas, although they live alone, are quite sociable. If two animals meet by chance, there will be no fight. During the mating season, males and females look for each other, creating married couples. But married life does not last for two days. After this, the bears disperse and the female herself raises the only cub, which is born in less than six months. The baby is almost 1000 times smaller than the mother and requires constant care and attention.

The smallest bird in the world is the BEE HUMMINGBIRD. The male reaches a length of only 5 cm, including beak and tail. The female is about 0.5 cm longer. In the air, hummingbirds are more mobile than birds of any other order. They feed by hovering near flowers. The flapping of their wings is so fast that they are almost invisible to the naked eye. These birds can fly up, sideways, forward and even backward. Hummingbirds live only in the warmest areas of North, Central and South America. Their sizes vary from 5 to approximately 20 cm, with the tail feathers making up almost half the length of the bird. Hummingbirds have colorful, shiny plumage, beautiful crests on their heads and long tail feathers. Females, as a rule, are not as brightly colored as males. The main food of hummingbirds is the sweet nectar contained inside flowers. Many hummingbirds have long beaks, which they plunge into the depths of the flower to obtain nectar.

BIRDS OF PARADISE - the most spectacular of all birds, got their name because of their beautiful plumage. Some are predominantly black with bright, sparkling iridescent feathers, while others are brilliant blue, red and yellow. Many birds of paradise have long, unusually shaped feathers on their tails and heads. There are more than 40 different species of these birds ranging in size from 13 to 107 cm. Most of them live in the rainforests of New Guinea, but several species inhabit the nearby Maluku Islands and the forests of north-eastern Australia. The main food of birds of paradise is fruit, although they also catch insects, spiders, and sometimes frogs and lizards. Multi-colored colors and “decorating” feathers are found only in males. Females look completely different, their plumage is mostly brownish. To attract the attention of females, the male hangs upside down. At the same time, the long tail feathers form a graceful arch above the cascade of its delightful blue feathers. The male sways back and forth, making creaking sounds. Most birds of paradise migrate alone. At the height of mating, birds of paradise emit piercing screams.

OEDIPUS TAMARINS.

The smallest and most beautiful monkeys are toys. These little animals, no larger than a rat, look very bizarre. The main decoration of marmosets is fur. Steller's and common marmosets have ears decorated with a fluff of long hair resembling flowers. The head of the Oedipal tamarin is crowned with a crown of long white hair. Their small size, bizarre coat color and additional decorations in the form of mustaches or crowns make these animals look like outlandish toys. A married couple at the head of a pack, sometimes uniting up to 15 individuals, keeps their subordinates strict. Marmosets can have offspring at any time of the year. Usually two babies are born. The mother takes the babies from the father only when it is time to feed. The cubs live with their parents for more than a year, but the older offspring are often expelled from the pack, and they form their own family groups.

SAKI MONKEYS are the “hairiest” among all prehensile-tailed monkeys. The long hair on the heads of these monkeys falls from the center in all directions, completely covering the ears and part of the face, forming a thick but neatly combed mop. The same long and thick “fur coat” covers the entire body of the saki, including a thick tail, which, by the way, is not prehensile, which distinguishes the saki from most of its prehensile-tailed relatives.

TIGER is the most beautiful animal on Earth. Currently, only 5 subspecies of tigers remain in the wild: Chinese, Indochinese, Bengal, Turin and Amur. Three species of tigers have gone extinct in the past 100 years. The Amur tiger is the largest - the weight of an adult male reaches 400 kg. Tigers, like lions, are terrestrial animals and hardly know how to climb trees, but unlike the latter they love water very much. Tigers are solitary animals, and an accidental collision between two males can lead to a brutal fight. Mother does not part with tigers until she is 2 years old. Females and young tigers hunt together and rest together. A tigress has an average of three cubs, but there are cases where eight sisters and brothers were born at once. Only Amur tigers give birth to babies in the spring or early summer so that they have time to grow and get stronger before the cold weather. Males do not take part in raising their offspring; this is the job of tigresses. The Amur tiger is not just a large cat, but the largest cat. The length of its body - from nose to tip of tail - is 3.5 meters. It lives in cold, snowy regions of eastern Asia. This is a very rare species of cat, there are less than 200 of them on Earth. They hunt, usually at night, for large mammals and sometimes travel up to 20 km in search of food.

CHEETAH is the fastest land mammal, capable of reaching speeds of up to 96 km/h from a standstill in just 3 seconds. It is not very hardy, so it tries to get closer to its prey and, instantly gaining enormous speed, catch it. If the first attempt fails, he does not pursue his victim. The cheetah is a unique creature. This is how a cheetah hunts. First, he watches a herd of gazelles, choosing a victim. In the sparse and short grass, gazelles would have long ago noticed a large lion, and the flexible cheetah can literally crawl along the ground, which allows it to sneak up as close as possible to its prey. Before the jump, the cheetah tenses, and then abruptly, like a spring, takes off from its place and with one blow knocks the gazelle off its feet. The mother carefully cares for her offspring - 4 kittens, protects them from predators.

BLUE WHALE is the largest animal on our planet. The record body length of this whale was 33.58 m, and the record weight was 190 tons. The weight of a newborn blue whale is 2 - 3 tons, and its length is up to 8 m. The baby drinks 200 liters of mother's milk per day. An adult blue whale eats 2–3 tons of plankton and small fish at one time. The height of the fountains thrown out by blue whales when exiting reaches 12 m. Blue whales live 35 - 40 years. Blue whales have up to 860 baleen plates, each about a meter long. The giant feeds on krill; in summer, it eats up to 4 tons every day. Today, there are only a few thousand blue whales left in the World Ocean. They are in danger of complete extinction. The blue whale opens its mouth wide, taking in a huge volume of water. He then strains it through rows of fringed baleen plates. At the same time, small animals remain in his mouth - krill, which this giant feeds on.

Life is at risk.

It is estimated that before the appearance of humans on Earth, one living species disappeared on average every thousand years, from 1850 to 1950 - one species per ten years (i.e. 100 times faster!), after 1950 - one year . And now every day (daily!!!) one species of plant, animal or mushroom disappears.

Some of the most famous animals destroyed by humans include the sea cow, the tarpan wild horse, the quagga zebra, the passenger pigeon, the dodo, and the great auk.

One of the most important tasks of humanity today is the preservation of biological diversity, that is, the diversity of species of organisms and natural communities. This is stated in a special international document - the “Convention on Biological Diversity” (adopted in 1992).

What do people do to save wildlife? Scientists are seeking the introduction of a ban on any destruction (gathering, hunting, catching) of creatures in need of protection. The destruction of all species listed in the International Red Book and the Red Book of Russia is prohibited. To breed certain species, special nurseries, reserves, and national parks are created, where not only individual species, but also entire natural communities are subject to protection.

Surprisingly many mammals can swim . Cetaceans and sirenians can reach quite high speeds and remain underwater for a very long time.
Mammals that live in water.
If necessary, almost all mammals can swim, but there are only two groups of these animals that spend their entire lives in the water and never go onto land - cetaceans and sirenians. Whales and dolphins are best adapted to the aquatic environment - they have lost body hair and live in water. Pinnipeds also spend most of their lives in water, and yet they come to land during the breeding season and during molting. This group includes true seals, eared seals and walruses. In addition, many four-legged, often furry animals are known to live on land, but spend a lot of time in the water. They descend into the water, both small animals - water beavers, otters, muskrats, and quite large animals, for example, a polar bear and a hippopotamus.

Way to travel
Over time, the limbs of some mammals turned into fins. Whales and manatees have a single horizontal fin instead of hind limbs.
In manatees it resembles a shovel; in whales the tail is forked like a fish. The upward movement of the tail is ensured by very strong special muscles, and the downward movement is controlled by weak muscles. The caudal fin moves only vertically. With the help of pectoral fins, animals change the direction of movement and maintain balance. In some species, the dorsal fin plays a very important role in maintaining balance. The streamlined body shape of waterfowl provides minimal resistance to water, and their smooth skin is elastic, which further reduces friction. To reduce friction, the skin of whales is covered with droplets of fat. The fastest and largest of the whales is the fin whale. Pinnipeds swim thanks to the movements of their front and hind limbs; they can easily change the direction of movement. It is interesting that real seals are quite clumsy on land, but their relatives, the eared seals, have excellent feeling both in water and on land. Each land animal, having adapted to life in water, expands its habitat and increases its opportunities for obtaining food. Animals also escape from enemies in water. Aquatic mammals sleep, feed and mate here.
locations
Visibility in the water is quite poor, and already at a depth of 200 m it is completely dark, so whales, dolphins and seals have a developed location system.
Animals use it to get the most complete picture of what surrounds them, with its help they communicate and look for food. Mammals make sounds whose duration does not exceed a thousandth of a second. When sound encounters an obstacle, it is reflected from it. By catching the reflected signal, the animal receives an accurate image of the object.
SWIMMING TECHNIQUE
Walruses, true and eared seals in the water in the movement of the front flippers. If animals want to increase their speed, they also use their rear flippers. Mammals that lead a semi-aquatic - semi-terrestrial lifestyle also use a similar style and work with all four limbs. Animals with long tails, such as otters and beavers, use them as rudder. The otter shrew in water keeps its limbs pressed to its body and moves due to wave-like movements of the body and tail. Its paws and tail are perfectly adapted for underwater hunting. Stiff bristles grow on the paws and underside of the tail. The Pyrenees muskrat has a swim membrane covered with coarse hairs between its toes and a long, flat tail. The muzzle of the Russian desman is adapted for air circulation. The beaver "rows" with its hind legs, using its wide and flat tail as a rudder. The polar bear spends a lot of time in the water and is one of the best swimmers among land mammals.
Diving
Whales have to rise to the surface to breathe, but one breath is enough for them to stay under water for even an hour. Some cetaceans dive to depths of about a kilometer, but records have been recorded that exceed this result. Seals exhale air before diving, and whales fill their lungs with as much oxygen as possible. Water pressure already at a depth of 100 m could rupture air-filled lungs, so whales “store” oxygen in their blood and muscles. Their circulatory system is very capacious, and the blood of these animals contains a lot of hemoglobin, which binds oxygen. During a dive to a significant depth, blood circulation slows down, which ensures the delivery of an adequate amount of oxygen to the brain. High concentrations of carbon dioxide in the blood do not harm whales. When a person breathes, nitrogen is released into the blood quite quickly. In whales, nitrogen exceeds the oil foam in the trachea and is immediately released upon reaching the surface.

Thermoregulation.

Mammals have developed two ways of protecting themselves from hypothermia in water. The fur of many animals, such as the beaver, muskrat and otter, consists of two layers of hair - a layer of long guard hairs protects against getting wet and covers a thick and warm undercoat. Having gotten wet, the guard hair creates a conduit - the shtovhuvalny layer. Between it and the undercoat there is a layer of air. This way the animal's undercoat always remains dry. The animal comes out of the water, shakes itself off, and its fur is dry again. The kutori does not have long guard hairs, but its velvety coat retains air bubbles. In the hole, the shrew presses against the walls to displace water from the wool. Mammals that spend their entire lives in water do not have hair. They are covered with smooth skin and have a thick layer of subcutaneous fat. In some whales it reaches a thickness of 30 cm. The whale can voluntarily regulate its body temperature by constricting or expanding its blood vessels. If you are interested in the children's club "PM 13 Kids Club", come in.