G. respiratory system

Dolphins are unique animals that live in the seas and oceans. They are distant relatives of cetaceans marine animals, only they belong to the dolphin family.

Due to its very graceful shape and smooth body surface, the dolphin is able to reach speeds of about 50 km / h, which is a very high speed.

Humans and Dolphins

It's no secret that dolphins are considered the most intelligent marine mammals. Dolphins showed their mind and ingenuity in those cases when the situation required it, for example, when rescuing people who were shipwrecked and preventing a person from dying at sea.

Therefore, most scientists who study the life and behavior of dolphins believe that dolphins have a very highly developed mind and intelligence. And only people are smarter than dolphins.

It is worth noting the fact that dolphins are related to the most dangerous and huge representatives of the ocean, whales and killer whales.

It is reliably known that in nature there are about 50 different species of dolphins. However, the bottlenose dolphin has the greatest popularity and fame of the species.

It is the Alafin dolphin that people most often mention in conversations. At the same time, this type of animal, due to its ingenuity and intelligence, can be quickly tamed.

Therefore, it is bottlenose dolphins that are most often filmed for various films, and this type of dolphin also has a good effect on children who have various diseases neurological nature.

Dolphin - description and photos. What does a dolphin look like?

Many people believe that a dolphin is a fish, but this is completely wrong, because a dolphin is a marine mammal.

Almost all species of dolphins have an elongated and smooth body, the length of some individuals can reach about 5 meters, while the head of the animal is connected to the body and is small in size, at the end of the head there is a mouth in the form of a beak.

In the mouth of a dolphin, there are from 75 to 100 small cone-shaped teeth, while almost all teeth have a slight slope inside the mouth, this is necessary so that the caught fish does not slip out of the dolphin's mouth.

Almost all species of dolphins have a dorsal fin that protrudes above the water. Moreover, by this fin you can determine what kind of dolphin is in the water.

How do dolphins breathe?

Since dolphins are considered distant relatives of whales, they are also able to stay under water for a long time, since Airways animals are closed.

However, dolphins periodically still float to the surface to take a few breaths.

Do dolphins have ears?

Physiologically, dolphins do not have ears by nature, but this does not mean that they do not have hearing. It definitely exists.

But the functioning of the hearing organs of dolphins works on a slightly different principle, not the same as in many mammals.

In a dolphin, all sounds are initially received by the inner ear, then the signal enters the so-called air cushions, which are located in the frontal part of the animal's head.

However, dolphins have very well developed echolocation, which makes it possible to accurately and without errors determine the distance to various objects, determine their size, as well as their location.

It should be noted that the dolphin is able to pick up the most ultra subtle sounds at a distance of tens of kilometers.

How Do Dolphins Sleep?

As for the sleep of these animals, there is one very interesting fact. The fact is that physiologically dolphins cannot fall into a full sleep. However, they still rest.

This process looks like this: dolphins in a semi-disabled state are in the water and only occasionally come to the surface to breathe.

In the process of wakefulness, dolphins turn off in turn the left and right hemisphere brain. Thus, one part of the brain is at work, while the other part is completely immersed in hibernation.

Where do dolphins live?

Dolphins are adapted to live in almost any part of the world. the globe, with the possible exception of the Arctic and Antarctic.

However, the main habitats are the seas and oceans, it is also possible for dolphins to live in freshwater Amazonian waters, where the Amazonian river dolphin lives.

These animals prefer space and can easily cover quite long distances.

Dolphin language

As a rule, all kinds of dolphins live in large flocks, where there can be from 10 to 120 animals, which gives them reliable protection from numerous enemies.

It is worth noting that within each flock there are no conflicts for leadership and so on. Between themselves, dolphins communicate exclusively using various signals and sounds.

At the same time, communication itself can consist of: whistling, twittering, barking, clicking. In this case, the frequency of the dolphin's voices can range from low-frequency to ultrasonic signal.

However, dolphins are able to link various signals and sounds together into the necessary information, which they are able to transmit over very long distances.

What do dolphins eat?

The basis of the menu in the diet of dolphins is only fish, but the most tasty fish for them are anchovies and sardines.

But dolphins hunt in a flock together, they use their specific sounds to make all the fish stray into one big school. After that, the dolphins take turns attacking the fish school. This is very effective method hunting for prey.

Dolphin breeding, baby dolphins

Dolphins, unlike many other mammals, do not have a specific mating season, so they can breed at almost any time. Mating with the female is done by the leader of the pack.

The gestation period of a female can last about 5 months, as a rule, it is very difficult. In this position, the female loses her dexterity and speed, she becomes slow and clumsy, as a result of which she becomes easy prey for enemies.

A female dolphin is able to reproduce one dolphin in two years.

At birth, a small dolphin has a length of about 0.5 meters, its birth takes place afloat, and from the first seconds of life, the baby is able to swim with its mother.

Dolphin babies feed mainly on mother's milk, as a result of which they gain weight and height very rapidly. The baby will eat milk until he is one and a half years old, it is during this period that the baby will begin to eat fish on his own.

Mothers take care of all the upbringing of babies, but males do not take part in this.

Photo of dolphins

Any creature needs rest to restore the body's strength. This is how nature intended it. Sleep is necessary for everyone - birds, mammals, any animals of a higher order, which include us - people. We are accustomed to associate sleep with a state of complete relaxation and immobility. This is how almost all representatives of a highly organized sauna sleep.

It is common for lions to sleep on their backs most of the day. Elephants in Africa tend to doze off standing up for two to three hours. Long-legged giraffes curl up to rest.

But how does a dolphin sleep? After all, no one had ever seen him motionless. These amazing animals always move in the water with extraordinary ease and grace. It seems that they are awake around the clock, and a sleepy state is not characteristic of them in principle.

But this assumption is wrong, which is finally proven by modern scientific research.

How do dolphins breathe?

We humans hardly ever think about our breathing - for us this process is natural. But with dolphins, things are a little more complicated. Every 5 or 10 minutes, any of the dolphins needs to surface to replenish their oxygen supply, which suggests the coordination of the muscles and the brain.

Everyone has long known that a dolphin is not a fish, but a real mammal. Moreover, they are considered secondary aquatic mammals. That is, their ancestors originally existed in the water element, but over time they mastered the land and were able to breathe with the help of their lungs. The reasons why such animals return to the water element are unknown to scientists.

Such mammals, unlike fish, do not have organs or adaptations that allow them to breathe underwater. That is, they do not have gills. To stock up on air for breathing, the dolphin needs to surface.

Respiratory organs of dolphins

Therefore, leading a life marine life, the dolphin continues to breathe with lungs. It has a special valve that the dolphin opens when approaching the water surface. Having exhaled and inhaled, the animal closes the valve and carries a fresh portion of oxygen under the water. This process is quite complicated for the body and is almost impossible in a sleepy state.

However, the received portion of air is enough, as mentioned above, for as much as five to ten minutes. For many years, biologists have been occupied with the quite obvious question - how does a dolphin sleep in this mode, because the time intervals through which this mammal must emerge in order to receive a portion of atmospheric oxygen are quite short.

Questions, questions...

Many versions have been put forward. The most extreme of them claimed that dolphins do not need sleep at all, that is, they never stay in this state. According to another theory, they are characterized by a short rest between ascents to the surface.

Do dolphins sleep at all? For a long time these animals were considered somnambulists, resting in a state of muscle tension and with open eyes. It was also believed that they are characterized by periods of sleep in short intervals between inhalation and exhalation, and they wake up from chemical changes in the composition of the stored portion of oxygen.

Some scientists attributed automatic actions to dolphins, like sleepwalkers. To determine true position cases, studies were organized in which it was supposed to register the biocurrents of the dolphin brain.

How a dolphin sleeps - word to science

This procedure is very difficult. The animals had to be placed in a pool, and electrodes were implanted into their brains. Recording of the given signals was carried out with the help of radio waves, which made it possible for the dolphins to lead their usual way of life.

The work was carried out at the Black Sea biological station by researchers from the Academy of Sciences. To finally find out how dolphins sleep, Soviet scientists A. Ya. Supin and L. M. Mukhametov, representatives of the Institute of Evolutionary Morphology and Animal Ecology, organized observation of mammals, which was carried out both in enclosures and in an open pool.

For implantation of electrodes into the brain, several specimens of bottlenose dolphins and azovoks were chosen. The animals were given the opportunity to habitually frolic, during which, using a radio signal, an electroencephalogram of the brain was recorded. The resulting drawing made it possible to trace the activity of each of its hemispheres.

What happened?

The results of the study, scientists were simply shocked. It turned out that complete immersion in sleep is not typical for dolphins. That is, their brain remains active continuously. The discovery was that his hemispheres in literally sleeping in turns. Each of them receives a portion of a full-fledged normal sleep for about 6 hours throughout the day. At intervals of an hour or an hour and a half, a replacement occurs when the opposite hemisphere falls into sleep.

The most interesting thing is that during such a dream, the dolphin can behave as if nothing had happened - swim, hunt, and so on. So it is hardly possible for outside observers to determine with the naked eye whether a given individual is sleeping at the moment or not.

How does a dolphin sleep - eyes open or not?

Almost everyone, both people and animals, close their eyes in a dream. And what about the dolphins? In full accordance with the alternate wakefulness of each of the hemispheres! That is, one eye of a sleeping dolphin is always closed.

Why do dolphins sleep with one open eye? Even before the study, many paid attention to the fact that one eye in dolphins is often closed, but no one had previously guessed to connect this with sleep. Thus, as a result of the study, a real scientific sensation was born.

It turns out that nature gave dolphins a truly magical opportunity to simultaneously relax and wake up. That is, complete and deep sleep, as in other mammals - with the shutdown of both hemispheres of the brain - never occurs in dolphins.

What does it look like

Now we understand how a dolphin sleeps. Each of the hemispheres alternately keeps its watch. Then they change places. The active hemisphere goes to sleep, the opposite begins to wake up. When the stage of sleep in a dolphin passes, both hemispheres are included in the work.

This evolutionary mechanism is provided by nature in order to survive the species. Constantly awake one of the hemispheres solves the issue of oxygen delivery to the brain and prevents the danger of choking.

The body size of a dolphin is about 160-260 cm. Males are approximately 10 cm longer than females. Dolphins are very slender, unlike other cetaceans, and their beak is long. The teeth are sharp and numerous, 2-3 mm thick. Top and bottom 40-55 pairs. There are two longitudinal grooves on the palate. The skin color of the back and all fins is dark, almost black, and only the belly is white.

Dolphins live in the water, but they are not fish. These are mammals and they need air to survive. breathe dolphins lungs, not gills. Under water, dolphins can stay on average for about 3-5 minutes, after which it becomes necessary to emerge and perform a respiratory act. For a long time, scientists could not solve the question of how a dolphin sleeps. Indeed, in the sea you can easily drown, or be a victim of other predators. But it turned out that the dream of a dolphin is not at all like the sleep of ordinary animals. During a dolphin's sleep, one hemisphere is at rest and the other is awake. So, a dolphin, having a full rest, constantly controls the situation.

Dolphins are capable of making about ten different sounds, similar to whistling, barking, clicking, etc. Range audio frequencies dolphins is between 3000 and 200000 Hz. Therefore, they can communicate on ordinary, and even on ultrasonic waves. When dolphins start barking, they are angry. A long, dull whistle that turns into a high and melodic one means that the dolphins are calling for help.

Dolphins have a unique hearing that works on the principle of an echo sounder. The range of an object, its shape, dimensions can be determined by dolphins by reflected sounds. In the surrounding space, dolphins are guided by hearing much more than by their sight. And this is fully justified, since visibility in the water is not very high.

The average cruising speed of dolphins is 35 km / h, and when they ride ship waves near the bow of a high-speed vessel, they reach speeds even more than 60 km / h. They jump with a "candle" up to 5 m high, and up to 9 m long.

Dolphins feed on schooling fish, cephalopods, and rarely crustaceans. During the day, an adult dolphin eats up to 30 kilograms of live fish. Such an amount of food is necessary in order to maintain a constant body temperature in any water, even very cold, which is quite high for them, because dolphins are warm-blooded mammals.

Dolphins live in packs. Dolphins are born about once every two years. During childbirth, the dolphin tries to jump high out of the water so that the baby can take its first breath. Dolphins are very touching parents taking care of their babies for about five years. But, even after reaching puberty, the cubs still remain strongly attached to their mother, and try to follow her everywhere. Dolphins live for almost 30 years.

The external nasal passage has three valves (one external and two internal) and two or three pairs of projections called nasal sacs. The first valve closes the external breathing hole (blowhole) for the period of the respiratory pause. Below the blowhole valve, the nasal passage expands slightly, on the sides of which, small slit-like openings open into the vestibular (dorsal) sacs. Vestibular sacs are located under the skin and covered with several layers of muscles. Under the vestibular sacs are tubular (tubular) sacs, which look like a tube in the shape of a semi-ellipse, covering the nasal passage on the left and right. The entrance to the tubular sacs is 8-12mm below the entrance to the vestibular sacs. The entrance to the left and right sacs are separated by a leathery septum, which rises obliquely upwards from the bridge of the bony nostrils. Opposite the entrance to the tubular sacs on the anterior wall of the nasal passage, there are two internal valves (internal nasal plugs), which are separated by the leathery septum indicated above. These valves are muscular-connective tissue formations and have independent muscles connecting them to the premaxillary bones and tissues of the frontal protrusion. With their free anterior and lower parts of the plug, they close the bony nostrils and the part of the nasal passage located between the tubular and premaxillary sacs. Immediately below the internal plugs is the third pair of bags - premaxillary. They form two tapering cavities directed forward. Their base is the premaxillary bones of the skull, and the dorsal walls are formed by the muscles of the nasal plugs and serve as the base of the frontal protrusion. It is also important to note that after the act of breathing, the nasal plugs close first, and then the valve of the breathing hole closes.

Larynx

It is a tube bent anteriorly, the narrow anterior-upper end is located under the paired nasopharyngeal opening (choanae), at the level of II-III cervical vertebrae passes into the trachea. The larynx consists of five cartilages, three unpaired (cricoid, thyroid, epiglottic) and one paired cartilage - arytenoid. The larynx occupies cervical region middle position, located closer to the ventral surface. The basis of the ventral and lateral walls is the thyroid cartilage.

Cricoid cartilage - unpaired, massive, is the basis of the laryngeal skeleton, because all cartilages of the larynx are connected with it, with the exception of the epiglottis. The epiglottis is an unpaired, most massive cartilage in the laryngeal skeleton of dolphins. In the larynx of dolphins, the epiglottis and arytenoid cartilages form the so-called arytenoid-epiglottic tube, which is unique to toothed whales. The anterior and lateral walls of the arytenoid-epiglottic tube are epiglottic cartilage, the posterior wall is entirely formed by the arytenoid cartilages. The arytenoid-epiglottic tube extends upward to the paired nasopharyngeal orifice of the dome of the pharynx. Being surrounded and constantly held by a powerful nasopharyngeal sphincter, the tube is located perpendicularly in the pharyngeal cavity and thus ensures complete and permanent separation of the respiratory and esophageal tracts in dolphins.

Consequently, the upper airways of dolphins have 2 muscular barriers that function as valves and isolate the nasal passage from the external environment: the first is located in the region of the supracranial nasal passage, the second in the region of the entrance to the larynx. The blowhole valve seems to play an additional role in relation to the indicated barriers.

Trachea

Trachea and bronchial tree

prodolphin (Stenella coeruleoalbus).

Visible trachea, bronchi, so

the tracheal is visible above the bifurcation

(preaortic bronchus, ventilating

cranial lobe of the right lung.

(photo, ventral side)

Short and wide oval tube with high strength and resistance to compression. The size of the trachea varies with the species, age, and size of the animal. It starts from the caudal edge of the larynx and goes into the chest cavity. At level III-IV of the thoracic vertebrae, the trachea, dividing into two bronchi, forms a bifurcation. On the right side, before the bifurcation, the third, tracheal (perdaortal) bronchus departs from the trachea (see Fig.). The trachea is dichotomously divided into two main bronchi, which ventilate the entire left and most of the right lung, with the exception of the cranial lobe, which is ventilated by the tracheal bronchus extending from the trachea above the bifurcation (see Fig.) Along the entire length of the trachea from the dorsal side and somewhat to the left of the midline is adjacent to the esophagus. From the ventral side, going to the lateral, the trachea covers the lobes of the thyroid gland. The skeleton of the trachea is represented by closed, anastomosing cartilage rings with each other. In the upper part of the trachea of ​​a dolphin, an epithelium of an unusual structure was found: multilayer, superficial cells are flat, in a reduced state the cells acquire a cubic shape.

main bronchi

They are divided into two branches of the second order. Large bronchi are cartilaginous tubes, cartilaginous rings are present in the main bronchi and in all bronchi up to the bronchi of the 5th order. Further, individual cartilage or closed cartilage rings are preserved. The bronchi of dolphins are characterized by the main type of branching. The alveolar septa in the lung of bottlenose dolphins are very thick and, compared to humans, have a well-defined collagenous interstitial tissue. The walls of all intrapulmonary bronchi are based on cartilaginous rings and plates connected by fibromuscular and elastic-muscular strands. The mucous membrane of the majority of intrapulmonary bronchi is lined with multi-row cylindrical epithelium. The terminal bronchi and subsequent 2-3 generations of the bronchi are lined with cuboidal epithelium that does not contain mucus-forming cells. In the submucosa of the bronchi and alveolar bronchioles there are numerous muscle fibers that form a system of sphincters that divide the bronchi into a number of chambers. Their number in one of the branches of the bronchial tree can reach 40. The surface of the bronchioles is lined with cuboidal epithelial cells. The sphincters located at some distance from each other in the smallest bronchioles entering the alveoli completely cover the lumen of the latter. They open only during the respiratory act. The role of the sphincters does not seem to be to close the lumen of the bronchioles, but, on the contrary, to keep them open to a certain level of pressure drop. A number of studies have given reason to believe that the purpose of these sphincters is that during diving they create an obstacle to the penetration of excess nitrogen into the blood, thus protecting the dolphin's body from decompression disorders.

Lungs

Micrograph of a lung of bottlenose dolphin T. truncatus. P - pleura, L - lung, capillaries are visible and alveoli are clearly visible.

The lungs of dolphins are not divided into large lobes, representing sac-like formations with a finely lobed structure. Clusters of alveoli with bronchioles make up small lobules, 15-25 such lobules form large lobules. The right lung is larger than the left, it is longer and heavier. The mass of light dolphins in relation to body weight (1.90 - 3.59%, depending on the type and age of the animal) significantly exceeds that of humans (0.7%). In terrestrial animals, the alveoli are separated from each other by thin partitions, which consist of layers of alveolar epithelium and capillary walls, inside which blood moves. Thus, the blood washes not one alveoli, but several adjacent to each other at once. In dolphins, each alveolus has its own capillary network. Alveoli are large (200-250 X 100-200 microns). The presence of elastic connective tissue and muscle fibers in the walls of the alveoli contributes to the active and rapid release of the alveoli from gases and filling them with inspiration.

The total lung capacity of a bottlenose dolphin is 10 - 11 liters (animal weight 130 - 170 kg), a porpoise is 1.4 - 2.1 liters (20 - 30 kg), while a person is 5 - 6 liters (70 kg). The minute volume of breathing at rest for the bottlenose dolphin is on average 14-16 l/min, while for a human this value lies in the range of 6-8 l/min. These indicators depend on the mass of the animal, its physiological state, age and gender.

Dolphins are very friendly creatures. They have long been famous for their initially benevolent attitude towards humans. Besides dolphins- very romantic creatures; so, in any case, they are perceived by ordinary consciousness. Not surprisingly, they are credited with magical powers.

Who are dolphins? Dolphins are mammals. 11 million years ago, their ancestors came out of the water to the land, looked around, were horrified, and returned back to the water. They have teeth, are warm-blooded, and feed their young with milk.

Where do dolphins live? They live in almost all the seas and oceans of our planet: from the most northern cold waters to the Red Sea. Some species of dolphins live in rivers, such as the pink dolphins of the Amazon. And the most common - bottlenose dolphin or small bottlenose dolphin - prefers the warm waters of the tropics.

How are dolphins born? The bottlenose dolphin's pregnancy lasts 12 months, and the baby is born tail first, with open eyes, developed sensory organs and sufficient coordination to follow the mother immediately after birth. After birth, the mother helps the baby to rise to the surface to take the first breath in life. The close bond between mother and calf lasts from three to eight years.

How deep can they dive? Some species of dolphins do not dive to great depths at all, others dive as deep as whales. Bottlenose dolphins rarely dive deep, often staying at recreational diving depths of up to 45 meters. The record for Atlantic bottlenose dolphins - 275 meters - this dive was made by a specially trained "military" dolphin Tuffy.

How fast can dolphins swim? Bottlenose dolphins usually swim at a speed of 4-11 km/h. To do this, they use the tail fin - the strongest part of the body. But if necessary, they can accelerate to 32 km / h. Their body is perfectly shaped for movement in the water, so they experience no resistance at all. The uniquely smooth skin also helps them swim through the water column, but that's why they've been scarred since childhood.

How do dolphins breathe? Dolphins breathe air. They do not have gills like fish do, but they do have lungs and a blowhole on their upper body. The same blowhole whales and dolphins use to make various sounds. Bottlenose dolphins usually hold their breath for an average of 7.25 minutes. But they can spend up to 15 minutes underwater.

What are they eating? All dolphins eat mostly various types fish and squid, depending on the region of habitat. They care about what they eat, and often dolphins prefer one or another type of fish. Their teeth and jaws are not designed for chewing, and dolphins swallow fish whole.

Dolphins smarter than people? The bottlenose dolphin's brain is about the same size as the human brain. But an elephant has a brain 4 times bigger! What matters is not the size of the brain, but the ratio of the brain and spinal cord, which in dolphins is 40:1, in humans 50:1, and in cats, for example, 5:1 (although this does not mean that they are stupid). The ratios, as we see in humans and dolphins, are very close. But it is important to remember that dolphins live in a completely different environment, which requires different intellectual abilities, speed of reactions and development of the senses. They have much more developed hearing, vision and other senses necessary for life under water.

How big can dolphins be? The largest dolphin in the family is the killer whale. At birth, they reach 2.5 meters and grow up to 6 meters in length. Bottlenose dolphins are less than a meter at birth, and rarely grow more than 2.5 meters.

Why do they make different sounds? Dolphins can make various sounds with their blowholes: whistling, pulsing sound, and clicks. The whistle is used for communication. Various pulsating sounds express emotional condition dolphins: anger, fear, excitement. Clicks serve to determine the direction - echolocation. These are the loudest sounds that marine animals make underwater.

Why don't they freeze in water? Dolphins are warm-blooded animals, their body temperature is about 36.6 degrees, and they need to keep warm in the northern seas. Water conducts heat 25 times more efficiently than air, so if we sit in water for a long time, we freeze much faster than at the same temperature in air. Dolphins keep warm thanks to a large fat layer right under the skin. In addition, they are able to control blood circulation and metabolism to maintain normal body temperature.

Are all dolphins the same? No. They are all different. Killer whales, for example, are bright, shiny, black and white. Other types of dolphins may be black or even pink. Bottlenose dolphins come in all shades of grey, but the belly is usually much lighter than the back. This allows bottlenose dolphins to be less visible on the surface of the water.

How long do they live? The average lifespan of dolphins is 25 years, although some dolphins live up to fifty. Often their life directly depends on us, our thoughtless activities in the vastness of the ocean.