Whales are perfectly adapted to the existence in the water, and the structure of each part of the body corresponds to their lifestyle. The body shape of the whale is cigar- or torpedo-shaped, so that when the whale moves, it experiences minimal water resistance. Whales have lost the hair that their land-dwelling ancestors had, and their smooth skin glides through the water with extremely little friction. True, some whale hair is still preserved in the form of small tactile antennae - vibrissae, in general similar to vibrissae in terrestrial mammals. Such antennae, growing at the mouth, have most species of cetaceans during their embryonic development, but not a large number of hairs are preserved in adult whales - around the lips and on the lower part of the head. The function of the completely lost hairline - the preservation of heat in the body, constantly in a cold environment, is now carried out in cetaceans by a thick layer subcutaneous fat.
A swimming whale sends its body forward with powerful blows of the tail, which at the end is divided into two large horizontal blades. These lobes and the dorsal fin - not all whales have it - consist mainly of skin and dense fibrous tissue; inside they do not have a lean base, such as fish have, whose fins and tail rest on hard fin rays. The forelimbs of whales, which have turned into fins, are used mainly for maintaining balance and for changing the direction of movement; the hind limbs are completely atrophied, at least they are not visible from the outside.
Food is the first and constant need of all animals. Large whales consume the vast amount of food supplied by the sea, and do so in two main ways. Some species feed mainly on squid or fish, catching their prey one by one, as predatory animals do on land. Whales that feed in this way usually have teeth and are therefore known as toothed whales (Odontoceti). Other species - baleen whales (Mystacoceti) swallow food "in bulk", like herbivores on land, which collect grass not only in one stalk, but in whole bunches at once. Although on occasion baleen whales will also swallow small fish, such as herring, as a rule, they feed on much smaller animals that teem in surface waters, which are a kind of "meadows" and "pastures" where whales "graze".
Baleen whales do not have teeth, but are equipped with a very special mechanism that allows them to capture their prey in huge portions. This is a filtering apparatus made of whalebone plates. On the upper jaw, where other mammals have teeth, baleen whales have two or even three hundred flat plates set obliquely along the edges of the palate and hanging from it. These plates are hard, but flexible, fibrous in structure, their inner edge is split in the form of a long coarse-fibred fringe. The fringed edges of neighboring plates are found one on top of the other and partly intertwined, so that if you look into the whale's mouth from the inside, then its inner side walls look like huge shaggy curtains. These "curtains" serve as a filter for straining food from water. When a baleen whale finds a large concentration of crustaceans, or "krill", it, opening its mouth, crashes into their mass, and the crustaceans fall into its funnel-shaped mouth in huge numbers. Then he closes his mouth and, raising his tongue, pushes water out of it through a filter formed by a whalebone. A fringed curtain traps plankton, and water flows out of the mouth through the gaps between the plates. Having swallowed the mass of food filtered out in this way, the whale fills its mouth again.
In fast and agile baleen whales, the surface of the throat, chest and abdomen is cut from the outside a large number longitudinal furrows; their length is from one to two thirds of the total length of the whale's body. These furrows, about 6 centimeters deep, are very similar to tram rails; they cut the skin even stripes. It is generally believed that when a whale feeds, the furrows expand, and thus the capacity of its mouth is greatly increased, but no one has ever seen this happen. Maybe some underwater swimmer with fins will be able to confirm or refute this assumption if he is so brave that he dares to repeat Jonah's adventure. In any case, it is clear that thanks to the furrows, the whale's mouth can be stretched. The proof of this is the following fact. After the death of a whale, the gases formed during decomposition fill this particular part of the body, inflating it, like balloon. Therefore, in cases where whalers catch so many whales that their carcasses cannot be processed quickly, these "balls" are pierced at coastal whaling bases so that they do not explode, since such an explosion poses a danger to workers.
The more voluminous, but less long true or smooth whales do not have furrows on their throats, but the capacity of their bucket-like mouth increases in a different way. The line of the lower jaw is strongly arched upwards, and the palate is narrow; the whalebone hanging from the baleen is very long: in the bowhead whale, for example, it reaches three or more meters, while even in the largest minke whales, its length does not exceed 1 meter. The lower jaw of right whales is far from the upper jaw even when their mouth is closed. The gap between the palate between the upper and lower jaws is closed by two halves of a huge lower lip, which rise to the right and left, like the sides of a coal bunker. Gray whale living in the northern part Pacific Ocean, is in this respect an intermediate form between minke whales and true whales: its upper jaw does not have such a pronounced vaulted structure.
Baleen whales consume food of various kinds, although in every region of the globe they are basically content with any one kind of it. But wherever they are, their diet always includes zooplankton.
Planktop is a collection of small animals and plants that live in the sea, but are so small that they cannot move independently over long distances, as fish, dolphins or whales do - they are carried from place to place by ocean currents. Although many representatives of zooplankton have the ability to move, they move not so much horizontally as vertically. Some of them sink into the depths during the day and rise to the surface at night, while others do the opposite.
The basis of the food of all animals living in the sea is plant microorganisms, which, using solar energy with the help of chlorophyll present in them, convert inorganic substances dissolved in water into organic ones. These plants are extremely small, each of them, as a rule, consists of only one cell, but their number is so large that, ultimately, it is they that form the food basis that ensures the existence of all marine fish, whales - both large and small. - and millions of other living beings. These single-celled plants - diatoms and dinoflagellates - are eaten by the smallest animals, and these animals are in turn eaten by large animals, and thus the food chain eventually stretches from the tiny diatom to the giant sperm whale. The chain leading to the baleen whale is shorter, as it feeds directly on plankton. Just as on land all meat is ultimately grass, in the sea all fish, whale meat and everything else are diatoms.
In addition to diatoms, there are countless other tiny organisms in the sea - both plant and animal, up to bacteria, which make up various links. the food chain. Some of these tiny organisms have a calcareous or silicon shell, which sinks to the bottom after their death, and over time sediments up to 100 meters thick or more accumulate on the ocean floor. Crustaceans are one of the most important links food chain- differ from other plankton in that they themselves feed on diatoms. And among them, a special place is occupied by small creatures - branched (schizopods) and copepods (Copepoda). These tiny animals, only a few millimeters long, have long, paddle-like antennae on either side of their heads, with which they swim. They are able to dive deep into the water, but by rowing with their antennae and other tiny limbs, they can stay level or even rise up. characteristic feature theirs is the presence of only one eye. For this, one of the species of freshwater copepods was named "cyclops".
Different types copepods make up in certain time year the main food for herring and mackerel, as well as for many other marine animals. But it is surprising that these same copepods - in huge concentrations - make up an equally significant part of the diet of the sei whale - one of the species of large baleen whales, which is distributed almost throughout the entire oceans. In Antarctica, the sei whale feeds on krill, like other baleen whales; in the northern hemisphere, however, it has been found to feed - at least for some time of the year - on the copeiodes, which teem with the surface waters of the ocean in spring and early summer. The sei whale can feed on these tiny crustaceans, but for the reason that its mouth is thinner than that of blue whales and fin whales, and the hair-like fibers that make up the filtering apparatus are soft, silky and crimped, so that they form a very dense veil in which even the tiniest animals linger.
Apparently, the most common planktonic crustaceans are shrimp-like ones, and the largest of them, euphausiids (their length is about 6 centimeters), live in the waters of Antarctica. In summer, they stay in the southern seas in huge clusters. From the moment they hatch from an egg to reaching full maturity, several years pass, and all this time, carried by currents for hundreds of miles, they travel from the ocean to different directions and at different depths. When they reach full maturity, they gather together in myriads, providing rich food for whales that swim in cold waters, accumulating subcutaneous fat due to these crustaceans.
"Krill" is a code name used by whalers to refer to swarming concentrations of small marine life; actually special kind there are no animals by that name.
But a rich "harvest" of crustaceans is collected not only by whales - many more marine animals feed on them: Antarctic penguins and other birds, crabeater seals (why they are called that), squids and huge shoals of various fish. That is why baleen whales, chasing crustaceans, sometimes swallow other animals along with them: fish, squid, and sometimes even a penguin or cormorant were found in their stomachs more than once, apparently eaten by accident when they themselves pursued the same crustaceans.
euphausiids (Euphausia superba) are commonly found in southern oceans, but other species of krill that baleen whales feed on are also found in northern waters. Accumulations of similar shrimp-like crustaceans, but only smaller in size, are sometimes found in the surface waters of the North Atlantic and the Pacific Ocean. These are also euphausiids. However, in the Arctic, plankton found in near-surface waters is often represented by many other animals. These are winged mollusks, or "sea butterflies", and related bivalve mollusks - oysters, cockles. They are all tiny creatures: the largest of them rarely reach 2 centimeters in length. Part of their body protrudes outward in the form of "wings", with the help of which these animals swim and get their own food, consisting of even smaller plankton. These wings are essentially fins, but they move with a flapping motion, which gives the mollusks a certain resemblance to butterflies. Some of them have a shell that looks like a small snail shell, others are completely devoid of a hard shell. For example, limacina (Limacina helicina) has a twisted shell with a diameter of about half a centimeter, and klion (Clion borealis), a tiny slug-like creature, dispenses with any shell. All these sea butterflies sometimes accumulate in such abundance that the sea changes its color for miles. In high latitudes, on the outskirts of the Arctic, huge flocks of klion served for a long time as the main food for the famous giant - the bowhead whale, which has been the main prey of northern whalers since ancient times.
Whales equipped with a filtering apparatus cannot choose certain types of food as they wish. And if they feed on any one species of zooplankton, it is only because these animals keep in such large and dense flocks that other species of zooplankton have almost no opportunity to mix with them. It happens that baleen whales, especially minke whales, eat small plankton-eating fish, such as herring, along with plankton, but usually these are the smallest herrings that swim in dense schools.
The nutrition of toothed whales is completely different. Their food consists of larger animals, which they swallow mostly singly. All toothed whales, regardless of their size, from the huge sperm whale to the common porpoise, feed on squid and fish, but their main food is squid. Squids, like tiny pteropods, belong to mollusks, but only they are the most highly organized representatives of this class. Unlike their relatives - octopuses and cuttlefish - they do not live at the bottom of the sea, but swim freely in the ocean at various depths. Due to the torpedo-shaped body and two fins located at its pointed rear end, they are very mobile. On their heads are big eyes and a crown of tentacles, of which two are very long, while the rest are much shorter. The tentacles are located around the mouth, equipped with oral jaws resembling the beak of a parrot. When the squid swims slowly, it uses only its fins, but when it needs to move quickly, it draws water into the cavity in its body and pushes it with force, as if through a tube, outward, due to which, with great speed, like a jet engine, moving forward in leaps and bounds. The inner surface of its tentacles is covered with numerous suckers, with the help of which it tenaciously holds the victim it has captured. Long tentacles, having suckers only at the ends, have the ability to retract inward, and then instantly eject forward. They grab the prey and pass it to the shorter tentacles, which are already forwarding it to the mouth. The surface of the suckers is horny circles, the edges of which are serrated, which helps to hold the prey even tighter.
Squids are found in the oceans in huge numbers, but it is difficult to catch them with the help of those devices or nets that biologists studying marine fauna usually use: they are so mobile and fast that they always have time to get away. But toothed whales and dolphins, better suited for such hunting, still know how to catch squid, and in the contents of their stomachs they usually find horny cephalopod beaks that are difficult to digest. Most of the squid that toothed whales feed on are small - 30-60 centimeters in length, but larger specimens are also found (these are usually swallowed by sperm whales).
An absolutely amazing sight is a giant squid, the length of which sometimes reaches 15 meters; however, in fact, it is not so huge: its length increases due to a pair of long tentacles, and the body and relatively short tentacles together make up 5-6 meters in length. These animals are rare, as they apparently live at considerable depths. Sometimes such giants are washed up dead by a wave to the shores, but more often they are found in the stomachs of sperm whales. Apparently, large squids, captured by a sperm whale, enter into a hopeless but fierce fight with him, as evidenced by the fact that the skin on the head of sperm whales and near the mouth is sometimes dotted with round marks left by the horny edges of the squid suckers.
Most dolphins have sharp and usually quite numerous teeth. It is usually believed that the presence of many teeth is a consequence of adaptation to the diet of such active and unusually mobile animals as fish and squid. But the beaked fish, for example, which also feed on squids, have very few teeth: it happens that only one pair erupts in them, and even then only in males, and more often there are no teeth at all. How the beaked whales capture their so agile prey is still unclear. At the same time, some of the freshwater dolphins, such as the Gangetic dolphin, have many needle-sharp teeth, which serve not to capture fast-moving prey, but to select worms and lobsters from the bottom silt.
Whales dive very deep into the sea and are subjected to great pressure. How do they manage to avoid decompression sickness? The answer is very simple - they are spared the risk of getting sick with it. At first glance, this seems strange, but with more scrutiny what is happening in the body of a whale, it becomes clear that there is nothing incomprehensible here. The difference between a whale and a man diving into the depths of the sea is that the diver under water breathes compressed air all the time, so that nitrogen can dissolve in his blood until he is completely saturated, and the whale takes with him into the depths only the amount of air that can fit in his lungs and airways when he inhales, so he doesn't have too much nitrogen in his blood and tissues.
When a whale dives, the pressure of the water is evenly distributed over the entire surface of its body, but since the body of the animal itself is 90 percent water, and water is practically incompressible, the whale's body does not deform. But the air in the lungs is compressible, and with increasing depth, the lungs of the whale are more and more compressed, so that the air from them is pushed with force into the windpipe and the airways leading to the blowhole. These airways are supplied with blood vessels much less than the lungs, so gas exchange in muscle tissues is reduced here. In addition, when the lungs contract, their tissue also becomes denser, so that the blood contained in the pulmonary capillaries is almost deprived of oxygen.
In addition, whales have another adaptation that allows them to dive so deep. The airways leading from their windpipe to the blowhole are not a straight tube, they are tortuous and connected with several complex lateral passages and extensive air sacs that fit snugly underneath the skull. These bags are filled with a foamy emulsion of water, fat and air, apparently absorbing nitrogen. When the whale swims to the surface and exhales, some of this foam erupts outward, carrying excess nitrogen with it. The visible fountain that the whale releases was usually thought to be a jet of water condensed in its breathing apparatus. In any case, there is no doubt that when the outside air is cold, the water vapor of the warm exhaled air condenses into fine liquid droplets. But this fountain is also noticeable in the tropics, where it is warm; there this visible jet is mainly foam. Although it is possible that even in warm air, the visible fountain is formed partly due to condensation: after all, the exhaled jet breaks out under pressure.
By the way, we note that these foam-filled sinuses also play a significant role in the whale echolocation system, but this will be discussed below.
The convolutions of the passage leading to the blowhole also serve as valves that prevent, on the one hand, the penetration of water into the respiratory organs of the whale, and, on the other hand, the escape of air from them when diving, when the whale opens its mouth under water to grab prey. Such an arrangement of the respiratory organs, extremely expedient in the conditions of underwater life, is, however, not only the result of adaptation to life in water. And the proof of this is the fact that a similar device is found in many land mammals.
It was believed that in sperm whales, which are known to go to very great depths, a thick subcutaneous fat layer serves as a kind of armor that protects them from water pressure, like a strong submarine hull. But a submarine doesn't open its mouth when deep underwater, so the analogy doesn't work.
The subcutaneous fat layer of cetaceans consists of adipose tissue in which cells filled with an oily substance are interconnected by fibrous connective tissue. Due to this, subcutaneous fat, contrary to popular belief, is not a soft, jelly-like substance, but a dense and hard, similar to the fatty edge of well-smoked bacon. The thickness of this layer ranges from 2 centimeters in porpoises to 30 or more centimeters in large minke whales, and in sperm whales and right whales this layer is even more powerful. The fat cover serves mainly as an insulating layer, keeping warm in the body of an animal in cold water.
But even whales sometimes feel the need to get rid of "warm clothes". When a land mammal moves very fast or expends some kind of effort, its body temperature rises and excess heat is removed from the body through rapid breathing or sweating. The whale, being in the depths of the sea, can neither sweat nor breathe rapidly, so from any efforts of his internal warmth increases rapidly. But its fat layer is permeated with blood vessels that bring blood directly to the surface of the body; blood circulation in these vessels is automatically regulated by their own muscles, and thus, when excess heat forms under the fat layer, body temperature is also regulated.
The change in blood flow to the fins also plays a significant role in the regulation of the whale's body temperature. The effectiveness of the whale's thermal insulation is especially evident when the slaughtered animal is delivered to a whaling base somewhere in the cold belt. If the whale carcass is not butchered immediately, it quickly decomposes and heats up under the fat layer so much - like garden manure piled up in a pile - that the meat is cooked. When the top layer of fat is stripped off, the meat falls off the bones like a stew.
The whale breathes by staying near the surface of the water. It plunges into the water along an inclined path, showing a ridge and a dorsal fin above the surface of the water. Going into the depths, the whale arches its body more than usual, and some species of whales throw their tail blades into the air, so that they become almost completely vertical in the water - "the whale dives," old whalers say in such cases. At this time, you can clearly see what a huge and powerful tail he has, like a propeller.
Whales have no hind limbs, only the rudimentary remains of the pelvic bones, not connected to the spine and hidden in the abdominal muscles, have been preserved from them. Some species of whales also have a pair of small bones, which are the remains of the hip bone. Despite their small size, the pelvic bones of whales, strictly speaking, are not rudiments devoid of any functions: they serve as a support for part of the reproductive organs.
For cetaceans, the specific structure of some blood vessels is very characteristic. As you know, in almost all mammals, during blood circulation, blood is pushed out of the heart and distributed through the arteries throughout the body. Arteries branch into smaller and smaller blood vessels and eventually pass into capillaries, that is, very small vessels, the walls of which are so thin that oxygen and other substances dissolved in the blood penetrate through them into the tissues, and carbon dioxide, along with other metabolic products, on the contrary, enters the capillaries from the tissues and is carried away with the venous blood flow. Capillaries, merging, form small veins, which, connecting, in turn, flow into larger veins, and they already carry blood back to the heart. In cetaceans, the circulatory system is characteristics found, however, in some land mammals. These features of the circulatory system consist in the fact that in some places large vessels are divided into many intertwined, as if entangled branches, which communicate with each other, forming a dense network.
These tortuous vessels are concentrated mainly at the base of the skull, run along spinal cord, under the ribs of the chest - in general, they diverge everywhere. They look so unusual that they were named retia mirabilia- "wonderful networks". The function and activity of this "network" of vessels is still not fully understood, but it seems that they serve as a kind of blood reservoir that can quickly fill or empty, thus regulating blood pressure during a whale's rapid sinking or surfacing. when the external pressure on the surface of his body suddenly and dramatically changes. It is possible that this network of vessels is something like elastic containers that are located along the course of the blood vessels and are able to instantly absorb a large amount of blood when it becomes necessary with an increase in external pressure.
When a whale dives, its large veins expand, blood flow through them is delayed - and blood circulation slows down. The sperm whale is able to hold its breath the longest: it can do without air for an hour, or even more. No land mammal can hold its breath for more than a minute or two. If breathing stops, the animal quickly loses consciousness due to the fact that oxygen stops flowing to the brain, and soon dies. When a dolphin dives, its heartbeat slows down sharply - from one hundred and ten beats per minute to fifty or even less, while in a beluga whale when diving, the number of beats drops from thirty to sixteen. Naturally, blood circulation in the body slows down and muscle tissues receive the oxygen they need more slowly, blood lingers in large veins and certain mechanisms begin to act that delay the movement of blood in all blood vessels, except for the vessels of the brain and some other organs. Oxygen entering the brain maintains its normal functioning, preventing loss of consciousness. But by the end of a long dive, the lack of oxygen in the tissues becomes noticeable, a kind of "oxygen debt" accumulates, which is compensated when the whale rises to the surface and "lets out fountains", that is, it begins to breathe quickly and intensively.
A whale can be under water for so long also because before diving it gains full lungs air, while his blood is extremely saturated with oxygen. But that's not all. Muscle tissue, or, as they say, the red meat of a whale, is of an intense dark red color, since it contains a large amount of myoglobin, a substance similar to chemical composition and properties to hemoglobin - the oxygen transporter of blood.
Before the animal is immersed, myoglobin is also completely saturated with oxygen, which creates an increased supply of it, and thus the "oxygen debt" in the body is delayed for a relatively long time.
Baleen whales usually do not dive deeper than 50-100 meters, because the largest concentrations of the zooplankton on which they feed are usually found at a depth of 10-20 meters. However, if necessary - if, for example, the whale is frightened - he is able to go to a depth of 300-450 meters. When minke whales feed, they usually dive for 10-15 minutes and then rise to the surface for 5-10 minutes to breathe. But in general they can stay under water for about 40 minutes. If after this period the minke whale does not rise to the surface, then it sinks.
Smooth whales and humpback whales are able to hold out under water even less and therefore go to a shallower depth. (For ordinary person the limit of breath holding is about one minute, and only well-trained pearl seekers can stay under water for two or even two and a half minutes.) But a sperm whale can be under water from 30 minutes to one hour. The bottlenose, according to some assumptions, stays under water for up to two hours. Whales of this species are able to go underwater to a much greater depth than baleen whales. The record depth of the sperm whale dive was set when a dead sperm whale was once found, which was entangled in an underwater telegraph cable laid at a depth of 1100 meters off the Pacific coast of South America.
Whales can develop very high speed. So, for example, a 25-meter blue whale can swim at a speed of 40-50 knots (74 - 92 km per hour) for two hours. And if we take into account that a swimming whale raises and lowers its tail relatively slowly, then the efficiency of the efforts that it expends when swimming, or, if I may say so, its efficiency is very high. The span of the blades of its tail is very large, and with each stroke of the tail a huge volume of water is thrown back, although at a relatively low speed. Thus, there is a smaller expenditure of kinetic energy than would be spent on moving smaller volumes at a higher speed.
If a whale expends 500 horsepower at 20 knots, that means that at that speed it expends 4 horsepower for every ton of its weight, which is 0.5 horsepower at 15 knots.
The muscular strength of an athlete is from 0.02 to 0.04 horsepower per 1 kilogram of his weight. If we correlate these figures with the muscular strength of a 120-ton whale, then it turns out that the whale can "squeeze out" 9 horsepower per 1 ton of its weight - this figure is no more than twice the figure given above. In other words, the muscles of a whale do not have more strength than the muscles of other mammals.
Small cetaceans, such as porpoises and dolphins, move faster through the water than would be expected from the amount of energy they can expend. Dolphins achieve extremely high speeds for such relatively small animals. A three-meter dolphin can move at a speed of 25 knots. A two-meter dolphin weighing about 130 kilograms must expend 14 horsepower to swim underwater at a speed of 25 knots - this effort, equal to 87 horsepower per 1 ton of weight, is more than six times the muscular effort that the most trained athlete can apply. The paradox that a dolphin can swim faster than its muscular strength allows it is not because it has unusually strong muscles, but because the surface of its body interacts with water in a special way.
When a rigid streamlined body is towed through water, the resistance to its movement remains small only until some critical speed is reached. The streamlined shape allows water to slide over the surface of the body without creating turbulence - in this case, the flow of water is laminar. But when the critical speed is reached in the laminar flow, whirlpools and eddies are formed - a turbulent movement occurs, in which, with increasing speed, the water resistance also increases.
Although, perhaps, cetaceans and not ideally streamlined, they are not frozen, motionless solid bodies, and living organisms - and this explains everything. The fact is that the skin of the whale, its fatty tissue and the muscles underlying them are so firmly, organically interconnected and at the same time so well innervated that the skin of the animal as a whole is unusually sensitive to the resistance of the aquatic environment - and at any speed the flow water flowing around the body of the animal remains laminar.
Internal structure The skin of cetaceans is characterized by the presence of peculiar papillae - outgrowths that penetrate from the inside into the corresponding cells of the underlying layers of the epidermis. Apparently, their function is not so much in adapting the skin to an increase in the pressure of the aquatic environment, but, perhaps, in dampening the resistance of water, in depreciating the oncoming flows that arise during the rapid movement of oncoming flows, that is, ultimately, in a significant reduction in friction, which reduces the speed moving body.
The eyes of whales are adapted to see in the water. But even the best eyes cannot see far underwater, no matter how transparent it is. And only an unusually sensitive echolocation device, or sonar, gives cetaceans the ability to navigate well even in turbulent water flows and at great depths, where there is either very little or no light at all.
The eye of a whale differs from the eye of land mammals by a very thick sclera - that outer cover, which in humans is called the eye protein. This sclera consists of a very rigid fibrous tissue, which, one might think, serves to protect the eyeball from deformation under the influence of pressure at great depths. But such an assumption would be wrong, since this sclera, itself consisting almost entirely of water, is incompressible, and the pressure in it is the same outside and inside. Perhaps the massiveness of the sclera is explained by the fact that it replaces the bone eye socket, which is absent in the skull of the whale, which protects the eyeball (in some land mammals, the eyes are also poorly protected).
If water environment does not allow you to see far, but it allows you to hear well: water conducts sound better than air. Therefore, the ear apparatus is the most important of the sense organs in cetaceans, although until recently, researchers thought that whales had poor hearing, and only the discovery of their ability to echolocate refuted this opinion.
The external auditory opening leading to the auditory canal is very small in the whale, while the internal auditory canal is quite large. However, usually they do not communicate with each other, since the external auditory meatus, bypassing the skin-fat cover, is greatly narrowed and, for some distance, is completely overgrown with fibrous and muscle tissue. Further inward, the passage opens again and gradually expands. Most of this cavity of the internal passage - up to the tympanic membrane, which protrudes strongly towards the external passage in the form of a finger of a rubber glove - is filled with a dense mass in the form of a cork from exfoliated, dead, tightly soldered cells and secretions of the glands. As the whale gets older, this cork grows, becoming covered with more and more layers. And by the number of such layers, one can determine the age of the whale, since, apparently, each successive layer is formed in one year.
The inner ear in whales - the organ through which sound waves enter the auditory nerve - like in other mammals, is located at the base of the skull and is protected by thickened bones that form a massive bony shell. In whales, this tympanic bone is unusually thick and massive, and is attached to the skull either by ligaments or thin bony pendants. Curiously, when a whale dies and its remains sink to the bottom, these massive tympanic bones do not succumb to the decomposition process for much longer than the rest of the skeleton. Therefore, it is these bones that are most often found at the bottom of the ocean and they are also most often found in the form of fossils.
Very little was known about the breeding of whales until special breeding programs were started in 1920. Scientific research in this area. Later, when they learned how to tame dolphins and keep them in captivity, many other details of their life became known. The duration of pregnancy for female dolphins is about eleven months. When the moment of childbirth approaches, the female begins to swim much more slowly than usual, and relatives surround her to protect and protect her during childbirth.
A baby dolphin is born already well developed, since immediately after birth it must be able to swim and follow its mother. Unlike other mammals, which give birth to one large cub at a time, in a whale, a cub is born tail first, and the relatively short umbilical cord breaks itself at the time of birth. As soon as the baby is born, the mother begins to gently push him to the surface of the water, and at the moment when his blowhole protrudes above the surface, he takes his first breath. The mammary glands of the female whale are under a layer of subcutaneous fat and do not protrude outward like an udder. The nipples are placed in the skin folds on both sides of the genital slit and protrude outward only during feeding. But the calf needs to breathe at short intervals, so feeding should take a little time. When the baby touches the mother's nipple, he does not have to make sucking movements, since the milk, thanks to the contractions of the female's muscles surrounding the mammary glands, is squeezed out by itself and pours into his mouth. In the first months of life, the cubs never swim far from their mother and, as a rule, swim with her side by side or under her head.
Kitiha mother takes great care of her offspring and never leaves the baby in danger. This is what whalers used in the old days: they harpooned the whale and dragged it along, knowing for sure that the mother herself would swim after him and fall into their hands.
Cetaceans are one of ancient detachments mammals; it is possible that they come from some ancestors common with land artiodactyls.
It is known that the oldest fossil whales lived in the Eocene, that is, about 40 million years ago. Some of them were similar in body shape to dolphins, others had a very elongated long body and looked more like giant eels (they are called Archaeoceti), but these animals were not the direct ancestors of today's whales, as they became extinct at least 25 million years ago. However, even before their appearance, there must have been two other ancestral lines leading to the current baleen and toothed whales. Their earliest fossils appear in the Oligocene deposits, that is, the existence of the most early forms cetaceans dates back to about 20 million years ago, and some fossils are even somewhat older. Thus, the whales living today are the descendants of countless generations that have come a long way of development.
You will learn what whales eat.
whales- These are marine mammals that have the largest sizes, up to 33 meters in length, and weighing up to 120 tons. There are baleen whales, which are distinguished by the presence of a whalebone to filter plankton from the water, and toothed whales that hunt fish and squid, and use echolocation.
What do whales eat in the ocean
The diet of the blue whale is practically no different from that of other minke whales. It is based on plankton - small crustaceans no more than six centimeters long, from the euphausian order. These crustaceans form entire clusters - the so-called krill.
whales eat and fish, but it is a small part of their diet. Most likely, fish and other small marine animals, such as squid and cuttlefish, are swallowed by them accidentally when eating their main food - krill. It is possible that if there are no large concentrations of krill, the whales begin to additionally feed on both small schooling fish and small crustaceans that are not krill.
In order to eat, the whale opens its huge mouth and draws water into it with a mass of krill, fish and small squid. The whale's mouth can be stretched, thanks to special stripes on the throat and a movable articulation of the bones of the lower jaw. After that, the whale closes its mouth and with its large tongue begins to squeeze the water back, filtering it through the baleen. The plankton lingers and is then swallowed by the whale.
The lower jaw of a whale is simply huge that it can hold up to 32.6 m³ of water. Because of this, it is sometimes difficult for a whale to close it. Therefore, having collected his food, he often turns on his side or back so that his mouth slams shut under itself. own weight. Due to their huge size, whales have to eat a huge amount of krill per day, and this amounts to several tons.
In the summer, when they gain weight to make up their energy reserves, whales eat up to three and a half tons of food, thereby building up a layer of fat. This fat will serve as insulation for them, protecting them from the extremely cold water temperatures at low latitudes. Now you know what whales eat.
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