Prove that the dolphin is a mammal and not a fish. Interesting facts about dolphins

A dolphin is a representative of the suborder of toothed whales, the order of cetaceans, the dolphin family (lat. Delphinidae). The graceful body of the dolphin has a spindle-shaped, streamlined shape, which allows these mammals to quickly cut through the surface of the water. The dolphin's speed reaches 50 km/h.

People and dolphins.

People have known about the extraordinary intelligence and intelligence of dolphins for a long time. These adorable animals rescue people from ships in distress, preventing them from drowning. You could even say that dolphins are the smartest animals on the planet. Many trainers believe that the intelligence of dolphins can be equated to that of humans, these animals behave so intelligently and unusually.

There is a joke about dolphins that says that if a person had not overtaken the dolphins and had not climbed down from the tree earlier, they would have come out of the water and now would have been the kings of nature, replacing us. The dolphin is smart, kind, beautiful, he is an excellent learner, analyzes and remembers.

Dolphins are directly related to formidable inhabitants oceans, killer whales and. There are about 50 species of dolphins. These include the harbor porpoise, black dolphin, gray dolphin, white-faced dolphin, and Atlantic white-sided dolphin. The most popular is the bottlenose dolphin (large dolphin), which is what people mainly mean when talking about encounters with representatives of this species. They are well studied and tamed. Bottlenose dolphins are featured in films and participate in programs for the rehabilitation of children suffering from various neurological ailments.

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

A dolphin is not a fish, but a mammal. Common to all species is an elongated, streamlined body, which is crowned by a small dolphin head with a beak-like mouth. Each jaw has 80-100 small conical teeth. The dolphin's teeth are slightly inclined inward. The transition between the muzzle and the frontal part is well defined. Almost all members of the dolphin class have a prominent dorsal fin. The skin is elastic and smooth to the touch. The length of a dolphin can reach 4.5 meters depending on the species.

Dolphins move very easily in the water; they practically do not feel its resistance thanks to special fatty secretions on the skin that facilitate gliding. Interestingly, the friction of water quickly wears off a dolphin’s skin. Therefore, in the deep layers of the skin they have a significant supply of regenerating cells. The dolphin constantly sheds, changing up to 25 layers of skin per day!

Dolphins have small eyes and poor vision. This is due to the fact that animals practically do not use them for hunting. The nostrils are transformed into a blowhole located on the crown.

How do dolphins breathe?

Whales and dolphins are related and can stay underwater for a long time without surfacing. The blowhole is closed during such periods. But, like other cetaceans, dolphins still need air underwater and periodically float to the surface to breathe.

Do dolphins have ears?

Dolphins do not have ears. But this does not mean that they have no hearing. Eat! True, it functions differently from other mammals. Sounds are perceived by the inner ear, and air cushions located in the frontal part serve as resonators. But these animals are fluent in echolocation. They accurately determine the location and dimensions of an object by the reflected sound, and the distance to it by the wavelength.

How do dolphins sleep?

Dolphins also have another interesting physiological feature: They never sleep. Animals hang in the water column, periodically rising to the surface to breathe. During rest, they are able to turn off alternately the left and right hemispheres of the brain, that is, only one half of the dolphin’s brain sleeps, and the other half is awake.

Where do dolphins live?

The dolphin's habitat is exclusively water bodies. The dolphin lives in almost all places on our planet, with the exception of the Arctic and Antarctic regions. Dolphins live in the sea, in the ocean, and also in large freshwater rivers (Amazonian river dolphin). These mammals love space and move freely over long distances.

Dolphin language.

Dolphins are animals social, they live in packs, which can number from 10 to 100 (sometimes more) individuals, fighting off enemies with common efforts. Within the pack there is practically no competition or fights between them; fellow tribesmen coexist peacefully with each other. Dolphins communicate using sounds and signals. Dolphin language extraordinarily varied. The “conversation” of these mammals includes clicking, whistling, barking, and chirping. The spectrum of dolphin voices extends from the lowest frequencies to ultrasound. Moreover, they can put simple sounds into words and sentences, passing information to each other.

What do dolphins eat?

The diet of dolphins includes exclusively fish; preference is given to anchovies. The hunting method used by the animals is also interesting. A school of dolphins finds a school of fish and uses special sounds to force it into a tight group. As a result of such hunting, most of the school becomes prey for dolphins. This feature is often used when attacking frightened fish from the air. There are known facts when dolphins helped fishermen by driving a school of fish into their nets.

Sharks and dolphins.

An interesting fact is that dolphins also live in symbiosis. They often hunt together without showing any aggression towards each other.

Types of dolphins.

There are 17 genera in the dolphin family. Most interesting varieties dolphins:

lives exclusively on the coast of Chile. An animal with rather modest dimensions - the length of the stocky and rather thick body of this cetacean does not exceed 170 cm. The back and sides of the white-bellied dolphin are gray, while the throat, belly area and parts of the flippers adjacent to the body are completely white. The flippers and dorsal fin of the white-bellied dolphin are smaller than those of other dolphin species. This type close to extinction, protected by Chilean authorities.

The length of the sea animal often reaches 2.4 meters, the weight of the dolphin varies between 60-80 kilograms. In the area of the back, the common dolphin is colored dark blue or almost black, the belly is white, and along the light sides there is a spectacular stripe of a yellowish-gray hue. This species of dolphin lives in the Mediterranean and Black Seas, and feels at ease in the Atlantic and Pacific oceans. Common dolphin can be found on east coast South America, along the coast of New Zealand and South Africa, in the seas of Japan and Korea.

a large representative of cetaceans with a body length reaching 3 meters and weighing up to 275 kg. A distinctive feature of the white-faced dolphin is its very light, sometimes snow-white muzzle. The habitat of this mammal includes the waters of the North Atlantic, the coast of Portugal and Turkey. The dolphin feeds on fish such as navaga, flounder, herring, whiting, as well as mollusks and crustaceans.

The body length of this marine mammal is 2-2.6 meters, weight varies from 90 to 155 kg. The height of the dorsal fin is 18-28 cm. The color of the dolphin is dominated by gray, with whitish spots scattered throughout it. This species of dolphin is common off the coast of Brazil, in the Gulf of Mexico and the Gulf of California, and lives in the warm waters of the Caribbean and Red Seas.

The length of the animal can vary from 2.3 to 3.6 meters, and weight from 150 to 300 kg. The body color of the bottlenose dolphin depends on its habitat, but generally the species has a dark brown upper body and a grayish-white belly. Sometimes a faint pattern in the form of fuzzy stripes or spots is observed on the sides. The bottlenose dolphin lives in the Mediterranean, Red, Baltic and Black Seas, and is often found in the Pacific Ocean along the coasts of Japan, Argentina and New Zealand.

distributed in the waters of countries with tropical climates, especially large populations live along the coast of the Hawaiian Islands. The torpedo-shaped, light gray body of the animal is crowned with a cone-shaped head of dark gray color. The length of the mammal often reaches 3 meters, and an adult weighs more than 200 kg.

This member of the genus of humpback dolphins lives in the waters along the coast Southeast Asia, but migrates during the breeding season, so it is found in bays, quiet sea lagoons and even rivers washing Australia and the countries of South Africa. The length of the animal can be 2-3.5 meters with a weight of 150-230 kg. Surprisingly, although dolphin calves are born completely black, as they grow, the body color changes first to light gray, with slightly pinkish spots, and adults become almost white. The Chinese dolphin feeds on fish and shellfish.

A distinctive feature of this type of dolphin is complete absence a beak on the muzzle and a flexible neck, which gained mobility due to several skin and muscle folds behind the head. The body color of the Irrawaddy dolphin can be either light gray with a blue tint or dark gray, while the belly of the animal is always a shade lighter. This aquatic mammal reaches 1.5-2.8 meters in length and weighs 115-145 kg. The dolphin's habitat covers the waters of the warm Indian Ocean, from the Bay of Bengal to the northern coast of Australia.

lives exclusively in Antarctic and subantarctic waters. The color of the dolphin is black and white, less often – dark gray. The striking white marking covers the sides of the mammal and extends to its muzzle, framing the eye area. The second mark runs longitudinally along the back of the body, intersecting with the first and forming an hourglass pattern. An adult cross-shaped dolphin has a body length of about 2 meters in length, the weight of the dolphin varies between 90-120 kilograms.

- a mammal that belongs to the dolphin family, the genus of killer whale. The male killer whale is about 10 meters long and weighs around 8 tons. Females are smaller: their length reaches 8.7 meters. The pectoral flippers of killer whales have a wide oval shape. The teeth of killer whales are quite long - up to 13 cm in length. The sides and back of the mammal are black, the throat is white, and on the belly there is white stripe. There are white spots above the eyes. Sometimes completely black or white individuals are found in the waters of the Pacific Ocean. The killer whale lives in all waters of the world's oceans, except the Sea of Azov, the Black Sea, the Laptev Sea and the East Siberian Sea.

It’s always quite difficult to pass up a dolphin show, because where else can you see such graceful and cheerful creatures! Therefore, dolphinariums are opened in many cities every year in the hope of attracting as many spectators as possible. But, despite such overwhelming popularity, an aura of mystery hovers around dolphins even today. And one of the mysteries: who are these amazing creatures? Are they fish or not?

An unimaginable mystery

The dolphin is a playful species that is found in many regions globe. Since it lives in water, inexperienced people are accustomed to considering it to belong to one of the fish species. After all, how else can one explain the fact that it can not float to the surface for hours? The presence of fins, which are an integral attribute of all inhabitants of the underwater kingdom, inclines them to the same conclusion.

However, scientists, having examined the characteristics of these creatures, came to a completely different conclusion. According to their research, the dolphin is a representative of the class of mammals. And its closest relatives are whales, killer whales and But why is that?

Irrefutable evidence

The fact that the dolphin is a mammal is evidenced by many factors. It is impossible to refute them, so all that remains is to accept this point of view. So, here's why a dolphin is not a fish:

They do not have gills, but instead the named creatures use lungs. Even if they are slightly different from those found in land mammals, they are still the same organ.
All dolphins are warm-blooded. Similar feature never found in fish.
These cute creatures give birth to live offspring, and do not lay eggs, as their underwater relatives do.
They feed their children with milk. That is why they are classified as mammals.
And finally, after examining the skeleton of dolphins, scientists found a lot of evidence that in the old days these sea creatures walked on land.

But how did it happen that they changed their usual habitat to water spaces? What made them move to new world? What is true story dolphin? And are there facts to support it?

Reasons for changing habitat

In fact, dolphins are not the only creatures that have changed one element to another. For example, the most famous case, this is when the first living organisms left the depths of the water and began to colonize land. True, in this case everything happened exactly the opposite. However, this is not significant for history. What's more important to her is why this happened.

Here scientists, unfortunately, cannot agree on a common opinion. But, most likely, the reason was a shortage of food on land, which is why some species had to adapt to other methods of hunting. In particular, the distant ancestors of all cetaceans, including dolphins, learned to catch their victims underwater. This was the impetus for them to spend more and more time near bodies of water until they completely moved into them.

Fossil record

In terms of historical evidence, paleontologists have been able to create a relatively accurate record of cetacean mutations. Naturally, there are some in it, but they are not so significant as to overshadow the whole picture.

The most ancient representative of cetaceans is Pakicetus. Its remains were found on the territory of modern Pakistan, and according to rough estimates by scientists, they are at least 48 million years old. Outwardly, this animal looked like a dog, only its thin paws ended in small hooves on the fingers. They lived near bodies of water, ate fish or crustaceans, and at the same time could plunge into the water in order to catch their prey. Pakicetus led a lifestyle similar to modern seals. Now let's look at more later ancestors cetaceans:

One of the subsequent stages in the evolution of Pakicetus was Ambulocetus, which lived approximately 35 million years ago. This predator was of very impressive size: for example, its length was about 3-3.5 meters, and its weight should have fluctuated between 300 kilograms. Outwardly, he looked like a crocodile and could live both in water and on land.
Another direct descendant of Pakicetus was Rhodocetus. The fossil animal was similar in appearance to modern seals, but had an elongated mouth with a row of fangs. He also had paws, at the end of which there may have been membranes, allowing him to swim quickly under water.
Basilosaurus is another potential cetacean relative. True, many scientists believe that he was more likely a relative of the killer whale than the forefather of friendly dolphins. This is due to the fact that the Basilosaurus had a huge size, allowing it to hunt almost all inhabitants of the seas.
Dorudon is a relative of Basilosaurus, living with it in the same period. He had much smaller body proportions. It is noteworthy that it was these dolphin ancestors who finally got rid of unnecessary paws and acquired a tail fin.

Mysteries of history

Many scientific works have been written about dolphins and a lot of research has been conducted, but today there are still many mysteries associated with their evolution. In particular, scientists cannot yet determine in what order some species replaced others. And yet the fact that these creatures once walked the earth does not raise any doubt.

By the way, with the development of genetics, many secrets of the universe began to gradually lose ground. So, recently scientists found out very interesting information. It turns out that hippos are distant relatives of cetaceans. It’s just that at one stage of evolution, dolphins went deep into the seas, and hippos decided to stay off the coast.

Well, let's discuss other features of these mammals. After all, the more we know about dolphins, the clearer the line that separates this species from other inhabitants of the seas and oceans becomes.

Developed intelligence

Playing dolphins bring interest and a smile to everyone who looks at them. However, only a few know that behind this behavior lies remarkable intelligence, which sets them apart from other animals. For example, only some species of primates that are closest to humans can compete with them in ingenuity.

Dolphins also have a complex communication system based on gestures and sounds. Thanks to this, they can coordinate their movement and hunt, like one well-coordinated mechanism. In addition, these creatures learn quickly, memorizing new images and movements at incredible speed. In particular, this is why they are so popular among circus performers and showmen.

The wonders of echolocation

Dolphins are one of the few animal species capable of using sound waves in their communication. Moreover, the strength of their signal is so great that their voice can spread over a distance of several kilometers. Rumor has it that in the past, the military used dolphins as underwater mine detectors, as they could find dangerous devices even in the murkiest and deepest waters.

The evil nature of dolphins

People believe that these creatures are very friendly, and their character is childlike. The dolphin is actually a very cruel animal. After all, he is a real predator and eats everything that is smaller than him.

However, the most cruel thing about his behavior is his offspring. So, if a dolphin gives birth to a weak calf, it can kill it. Not to mention the fact that there are cases when these creatures attacked other representatives of their species, fighting for territory, or simply because of personal enmity.

Almost all species of dolphins live in warm salty waters. There are 47 of them in total. These are the indigenous inhabitants of the seas and oceans. But besides marine mammals, there are also river dolphins, which are separate family, which includes 6 types. These animals live in the rivers of India, China and South America. Their habitat is the Ganges, Indus and Brahmaputra in India. In China they can be found in Lake Dongtinghoe, and in South America they have chosen the Amazon, Orinoco and La Plata.

River dolphins they are inferior in size and weight to their marine relatives and have a more primitive brain structure. The body length of these animals usually ranges from 1.5 to 2.5 meters, and the weight is never less than 40 kg, but does not exceed 120 kg. The bodies of river animals are usually brown or almost white, although sometimes dark carcasses are also found. The vision of these mammals is very weak or almost completely absent. The most characteristic difference from their marine counterparts is the cervical vertebrae. They are not fused into a single bone like those of ocean inhabitants, but are divided just like those of land mammals.

Dolphins for the most part are heat-loving animals. Cool waters They only like certain species. These include striped dolphin. It is common in the North Pacific Ocean. It can be found off the coast of Sakhalin and the Kuril Islands, in the waters adjacent to California and Japan. This mammal reaches a length of 2.2-2.3 meters. Average weight is 140 kg. The maximum weight of males can vary between 180 kg. Females are never lighter than 100 kg.

This is a very lively, fast and energetic dolphin. It can often be seen from the sides of ships. Swift, graceful bodies with dark narrow stripes on the sides can accompany the ship for a very long time. Moreover, the animals not only swim in a parallel course, but also easily overtake the floating craft, cross its path and make various jumps and pirouettes.

The striped dolphin's closest relative is common dolphin. Along with the shores of Canada, England, Korea and Japan, it also loves the warm waters of the Mediterranean and Black Seas. It can also be found off the coast of Australia, where the animal feels quite comfortable. The dolphin is very graceful and the fastest of all its sea counterparts. In water it easily reaches speeds of 60-70 km/h. Loves to jump. Their height reaches 5 meters.

The color of the squirrel is very beautiful. The back is black with a greenish tint, and the belly is white. The eyes are surrounded by black circles. The dolphin reaches a maximum length of 2.4 meters at medium length 2 meters. The weight of the animal is about 110 kg. The common dolphin has a high dorsal fin: its height is 80 cm. These mammals live in large schools and love to frolic near the water surface.

Dolphin species would have lost a lot if there had not been such a representative among them as bottlenose dolphin. This is a large mammal, reaching a length of 2.3-3.2 meters. Sometimes you come across bottlenose dolphins of more impressive size with a body length of 3.6 meters. The mass of this dolphin is usually within 300 kg. The maximum weight reaches 400 kg. The habitat of this animal extends to all temperate and warm waters World ocean. Bottlenose dolphins can be found in the Black and Mediterranean Seas, in Indian Ocean, in the Atlantic and in the Pacific, where he is very fond of the waters washing the shores of Southeast Asia and Australia.

The body color of different individuals is not the same, but varies in shade. Mostly dark brown back and gray belly predominate. There are animals with white bellies. Sometimes you can find a representative of the species whose entire body is a uniform gray color. The speed that a bottlenose dolphin develops in water is 40 km/h. He got along very well with the person and friendly relations. The dolphin is highly trainable and even learns some words spoken by people. This species performs in dolphinariums more often than any other, impressing spectators with its skill.

Without exception, all species of dolphins have one characteristic feature. Sometimes they are in large quantities wash ashore and die. Experts explain this phenomenon in different ways. The prevailing point of view is that such suicides are the result of the work of certain brain centers of the animal, directly related to the generation of high-frequency sounds. Sometimes the established frequency of vibrations of the earth's surface resonates as a result of the influence of external vibrational sources on it. These could be wind, tremors in the earth's crust, or the operation of ship radars.

The modified frequency signal may match the sound made by a wounded dolphin. It’s like a person to whom sometimes the howling of a storm outside the window seems like the cry of a child. Let us remember A.S. Pushkin: “Then she will howl like a beast, then she will cry like a child.” A nearby flock perceives such a signal as a call for help. She quickly rushes to the coast, washes ashore and dies. Similar actions are observed in all marine mammals that do not abandon their fellows in trouble (for example, in the same whales), which once again confirms the correctness of this version.

Dolphins are one of the most mysterious animals on our planet. The intelligence of these sea inhabitants is considered so high that they are called “people of the sea.” Scientists say that dolphins are smarter and smarter than all other animals.

Dolphins live in water, but they are not fish, but mammals from the order Cetacea. That is, they need air - they breathe with their lungs, not their gills. People can always see dolphins' faces on the surface of the sea because dolphins can stay underwater for an average of about 3-5 minutes (although dolphins have been recorded underwater for 10 to 15 minutes). Dolphins feed their young with milk.

Dolphins are found in many seas and oceans of the world, including the Black Sea.
Dolphins live up to 75 years, most often about 50, in captivity usually about 30. With the help of its 88 teeth black sea dolphin eats about 30 kg of fish per day, the mass of dolphins is up to 500 kg. The body temperature of a dolphin is the same as that of a person - 36.6 degrees. The gestation period of dolphins is about 12 months. The female dolphin usually brings one calf 50-60 cm long and carefully guards it for some time.

When you mention a dolphin, you are more likely to think of the species Bottlenose Dolphin (Tursiops truncatus). Bottlenose dolphins owe their popularity partly to numerous references in cinema and fiction and their high ability to learn.

The skin of dolphins is a miracle of nature, they are able to dampen the turbulence of water near the surface of a fast-swimming body, which reduces the speed of movement - submarine designers learned from dolphins, creating artificial skins for submarines. And the feeling of dolphin skin to the touch is completely unusual, and also brings joy: it looks dense, like it’s made of plastic, but when you run your palm over it, it’s tender and soft, it seems like thin silk.

When dolphins began to be studied and trained in the middle of the last century, the first results of this work seemed so unusual, and even surprising (they talked about it a lot, wrote about it and made films), that gradually a legend about the unusual high intelligence dolphins; one could often hear that they were no more stupid than a person, only their minds were different.

The brain of an adult dolphin weighs about 1,700 grams, while that of a human weighs 1,400. A dolphin has twice as many convolutions in the cerebral cortex. At the same time, there are relatively few neurons per cubic millimeter of its substance (less than in the brain of primates).

The results of studies on the behavior and physiology of the brain of dolphins are very contradictory. Some put their ability to learn at about the level of a dog and show that dolphins are very far from chimpanzees. Research on the communication methods of dolphins, on the contrary, leads to the conclusion that we have not yet come close to understanding this form of life in natural conditions and it is simply incorrect to compare the level of intelligence of dolphins and chimpanzees. One property of the dolphin brain is completely unique: it never really sleeps. The left and right hemispheres of the brain sleep alternately. The dolphin needs to come to the surface from time to time to breathe. At night, the waking halves of the brain are responsible for this, in turn.

The language of dolphins can be divided into 2 groups: Body language (body language) - various poses, jumps, turns, various ways swimming, signs given by the tail, head, fins.

The language of sounds (language itself) is sound signaling, expressed in the form of sound impulses and ultrasound. Examples of such sounds include: chirping, buzzing, squealing, grinding, clicking, smacking, squeaking, popping, squeaking, roaring, screaming, screaming, croaking, and whistling.

The most expressive are whistles, of which dolphins have 32 species. Each of them can denote a specific phrase (signals of pain, anxiety, greetings and a calling cry “come to me,” etc.). Scientists studied dolphin whistles using Zipf's method and obtained the same slope coefficient as human tongues, i.e. carrying information. IN lately About 180 communication signs have been discovered in dolphins, which they are trying to systematize by compiling a dictionary of communication between these mammals. However, despite numerous studies, it has not been possible to completely decipher the language of dolphins.

Each dolphin has its own name, to which it responds when its relatives address it. This conclusion was reached by American scientists, the results of which were published in the Bulletin of the US National Academy of Sciences (PNAS). Moreover, experts who conducted their experiments in the American state of Florida found that the name is given to the dolphin at birth and is a characteristic whistle.

Scientists caught 14 light gray bottlenose dolphins in the wild with nets and recorded various sounds, published by these mammals in the process of their communication with each other. Then, using a computer, “names” were extracted from the records. When the name was “played” for the flock, a specific individual responded to it. The dolphin's "name" is a characteristic whistle, the average duration of which is 0.9 seconds.

Everyone has heard that sometimes dolphins and other whales wash ashore. Sometimes this happens due to illness, poisoning or injury. There is another hypothesis that explains the reason for such strange behavior of dolphins: it turns out that with a certain shape of the coast, composed of certain types of sediment, among the cacophony of sounds generated by the surf, a sound sometimes arises that exactly corresponds to the cry of a dolphin for help. Animals, hearing these sounds, instinctively rush to help - and end up on the shore.

Dolphins eat fish. A lot of fish: each member of the flock should eat 10-30 kilograms per day. Dolphins are warm-blooded, they need to maintain a high body temperature, sometimes very cold water. The subcutaneous layer of fat also helps with this - it acts as a heat insulator and source of energy for the intracellular oven: burning fats and carbohydrates with the release of thermal energy. Fuel reserves need to be replenished all the time, so they constantly hunt. They catch up with a school of fish - no one in the sea swims faster than them - and surround it. If this happens very close to the shore, the dolphins form a semi-ring and press the fish to the beach; compressing their hunting formation, they push the fish into the shallowest water and eat it there - while they swim into the very waves of the surf, so shallow that their dorsal fins stick out of the water, and their pectoral fins touch the sand at the bottom.

Having surrounded a school of fish further into the sea, the dolphins do not rush, each individually, after the prey, but organize the school in a ring, preventing the fish from scattering, and one by one plunge into the school. Having caught prey, they return to their place in the pen.

Where there are fish, there are dolphins. U Black Sea coast the fish are most abundant in spring and autumn - when schools of mullet and anchovy go to the Sea of Azov for summer feeding, or return to winter in the Black Sea - along the coast of the Caucasus. Therefore, dolphins most often appear here in April-May and September-October. And in fact Kerch Strait– the gates of the Sea of Azov – hundreds of dolphins stand at the outpost, meeting migrating fish stocks.

In summer, bottlenose dolphins also often come straight to the beach - they are more often seen in the early morning or afternoon - perhaps because there are fewer swimmers at this time.

Dolphins live in schools, in which everyone is relative, which is why their mutual assistance is so well developed. They always help a weakened dolphin stay near the surface so that it does not choke; There are stories of how dolphins came to the aid of drowning people. They never act hostile. Dolphins learn tricks very quickly - they only need one correct execution of an exercise on a signal, for which they are rewarded with a fish, so that the skill is fixed in memory. True, they also easily forget their skills if the coach forgets to reinforce a useful habit.

Dolphins live for about 30 years. Dolphins are born approximately once every two years. At this time, the dolphin tries to jump high so that the calf can take its first breath. Dolphins are very touching parents, caring for their young for about five years. And even when reaching puberty, the cub still remains strongly attached to its mother and tries to follow her everywhere.

For a long time, scientists were puzzled by the question of how dolphins sleep. After all, in the sea you can easily drown or become a victim of attack by other predators. However, it has now turned out that the sleep of dolphins is not similar to the sleep of ordinary animals - during sleep, one hemisphere of the dolphin rests, and the other is awake. Thus, the dolphin is always in control of the situation and, at the same time, gets complete rest.

Definitely, something makes us treat dolphins differently than other animals - “friends of man”... Friendly, cheerful, cute... They are really friendly and curious: they are not afraid to swim up and play with a person, although more often - or not pay attention to people, or simply swim away - they have their own worries at sea. Maybe it's the dolphin's smile? After all, they always smile - for some reason, that’s how their face is structured (I don’t even want to call it a muzzle!). And this smile with big eyes is one of those smiles that makes us involuntarily smile back - not all people know how to smile like that.

Dolphins (Delphinidae) are the most beautiful representatives of CETACEANS with an ELEGANT AND CURVED BODY, LIKE A SPINDLE, WHICH IS ideally adapted for movement in water and ALLOWS IT TO SWIM VERY FAST. Dolphins belong to the class of mammals, the order Cetaceans, DEPENDING ON THE TYPE OF DOLPHINS' BACK IT WILL BE BLACK, DARK BROWN or gray, with white sides and belly. They have very elastic and smooth skin. They experience virtually no resistance from water thanks to oily secretions that make it easier for water to glide over their skin. They have a very distinctive muzzle. In some species it even ends with a real “beak”, albeit slightly flattened. The mouth is equipped with many strong teeth - from 80 to 100 on each jaw; with their help, they manage to easily hold food in their mouths. Like all other cetaceans, dolphins need air, so they rise to the surface and breathe, loudly puffing, through the nasal opening - a blowhole, located right in the center of the head, and under water it is always closed .
Dolphins are fairly large aquatic mammals, body length from 3 m to 4.20 m. Weight - from 150 to 300 kg. Males are 10-20 cm longer than females. Dolphins live from 30 to 50 years natural conditions and 7 years in captivity. The age of puberty is between 5 and 12 years for females and between 9 and 13 years for males. Mating occurs throughout the year, but the most favorable period is from March to August. The male and female choose a new partner every year. The female carries one baby for 12 months, this happens once every 2-3 years. The baby is born almost 1 m long. The mother feeds him with very nutritious milk for 6 months. Cubs are born in the summer. Females give birth and raise them directly in the water. Together with the babies, they swim in the center of the school so that the males can always protect them.
Dolphins are warm-blooded animals and are able to maintain a constant body temperature. Dolphins feed on a variety of fish (capelin, anchovies, salmon), as well as cephalopods (squid, shrimp). In order to catch the desired type of fish, some ocean species of dolphins can dive to a depth of 260 m. They swim very quickly, reaching speeds of up to 40 km/h. Everyone knows the jumping of dolphins. They are able to jump vertically to a height of up to 5 m, and horizontally - up to 9 m. Dolphins are able to move quickly in the water column thanks not only to the streamlined shape of their body, but also to the special structure of their fins and skin, which can change elasticity depending on the density of the water. This allows dolphins to develop maximum speed and catch up with even the fastest inhabitants of the seas and oceans. They are good hunters. With the help of directional echolocation, when a dolphin sends ultrasound to a target, it can easily determine the exact location of its prey. Dolphins also communicate through ultrasound; their hearing is very well developed, so they can communicate over considerable distances. In addition to ultrasound, dolphins can produce various sounds of medium frequency - creaks, clicks, whistles, etc. Dolphins are able to quickly dive to great depths, up to 100 m, and they do not show any signs of decompression sickness, like in humans. This is due to special structure their circulatory system, the composition of blood and tissues, which contain a lot of water. When diving, a dolphin’s heart begins to beat very slowly, and when emerging, on the contrary, it starts beating quickly. Their breathing occurs while emerging from the water. Inhalation and exhalation take less than 1 second. The breathing rate of dolphins per minute is very rare - only 3-5 inhalations and exhalations. During exhalation, air, along with tiny droplets of water, is thrown out through the blowhole in the form of a powerful fountain of water, beating high up. During sleep, the dolphin swims 50 cm from the surface of the water, rising every 30 seconds to take in air. He does this automatically, without even waking up. The dolphin spends his days hunting, playing and "talking" with his fellow creatures. In general, this is a very smart and sociable animal. You can often see a dolphin helping a wounded or sick fellow tribesman. He can also save a person who has fallen into the water. They even saw dolphins bringing small boats to land that were carried far out to sea by the current.

Dolphins do not like loneliness and in the vast majority of cases they live in numerous schools where any action is performed together with their comrades. They do not have a leader. They hunt by pouncing on entire schools of fish, and have fun performing their famous jumps one after another. The main enemy of the dolphin is its relative the killer whale. In some regions, people still continue to hunt dolphins.
Many people believe that there is only one species of dolphin. In fact, there are about 40 of them, all of them are different, and sometimes the differences between them are very significant. The most famous species is the bottlenose dolphin, which can often be seen in the Black and Mediterranean seas.
Dolphins can be found in almost any sea and ocean of the world. But they prefer the coastal waters of warm seas - in the temperate climate zone and the tropics. Among dolphins, according to their habitat, two species are distinguished - those living in the oceans and those living in the seas. They differ mainly in the depth of immersion and food preferences. In our country, dolphins are found in the Black and Baltic Seas.
In the middle of the 20th century. A huge number of dolphins lived in the Black Sea. According to rough estimates, the population included 2.5 million individuals. But the development of industry and the pollution of sea waters with sewage led to the gradual extinction of dolphins, since they can only live in clean water. Their industrial production also played an important role in the mass death of dolphins. Before the ban on mass catching of dolphins, it was carried out using special nets that mutilated the animals.
Two rare species of dolphins live in the waters of the North Atlantic - white-sided and white-faced.
The white-sided dolphin reaches a length of 2.7 m, with females being slightly larger than males. It differs from the white-faced dolphin in having shorter pectoral fins and a distinct white stripe on the sides. The white-faced dolphin has a white “beak” and the front part of the “forehead”. Body length does not exceed 3 m. Well developed pectoral fins(up to 0.6 m in length).
White-sided and white-faced dolphins are found mainly in the Barents Sea, sometimes entering the Baltic Sea. Their number in
Russia has not been identified; outside the country they live in the Norwegian and North Seas. The fishery has survived only off the coast of Norway. In Russian territorial waters both species are protected. The food diet of dolphins consists of bottom and bottom fish (cod, flounder, navaga), they feed less frequently on mollusks and crustaceans. White sided dolphins love to accompany sea vessels. Getting into the flow of water from the ship's propellers, they reach speeds of up to 6 km/h. In the shallows, there are frequent cases of white-sided and white-faced dolphins drying out.
During a group drying off on the shores of Ireland in 1988, 57 animals simultaneously died. Fishing nets also pose a danger to dolphins, in which they often become entangled and die.
Bottlenose dolphin. This large dolphin, distributed throughout the hot and temperate zone, probably the most studied and tamed, it is not for nothing that he plays the role of Flipper. Every day he is entitled to 8-15 kg of fish (anchovies, sardines, mackerel), cuttlefish and squid: after all, 4 m in length! Bottlenose dolphins adapt well to captivity, easily learn various tricks and enjoy performing in front of spectators.
The Black Sea bottlenose dolphin is a medium-sized dolphin (length up to 2.5 m, weight from 150 to 320 kg). It feeds on fish, diving to a depth of 100-150 m and remaining under water for 5-10 minutes. Black Sea bottlenose dolphins stay in small schools and can reach speeds of up to 40-50 km/h. They tolerate captivity well and are amenable to training.
In the first half of the 20th century. Black Sea bottlenose dolphins were numerous in the Black Sea. Severe water pollution and heavy shipping have caused their numbers in coastal areas to sharply decline. In 1966, the USSR stopped fishing for bottlenose dolphins, then Bulgaria and Romania abandoned dolphin fishing. However, despite the long ban, the number of dolphins in the Black Sea is not increasing. The reason is most likely the continued fishing in Turkey. At the end of the 80s. XX century The number of bottlenose dolphins was 35-40 thousand individuals. Included in the IUCN-96 Red List and Appendix II of the CITES Convention.
The gray dolphin reaches a length of 4.3 m, feeds on cephalopods and is capable of staying under water for a long time. In Russian waters, this species is found along the Kuril and Commander Islands. Its number has not been established.
In recent years, there has been a decrease in groups of dolphins near Kuril Islands This is apparently due to their capture in Japanese waters for keeping in oceanariums. Included in the IUCN-9c Red List and Appendix II of the CITES Convention.
In the rivers of Asia and South America, and especially in their mouths, there are river, or freshwater, dolphins, which form a separate family. River dolphins are the oldest family of toothed whales. It includes the Gangetic (Susuk), Laplatian, Chinese Lake and Amazonian Inia. With their long thin snout they rummage through the bottom mud, looking for worms and crustaceans. IN muddy water They hardly need vision; they compensate for it with echolocation. With its help, they can distinguish copper wire with a diameter of 1 mm!
The COMMON DOLPHIN is a cetacean with a strong build and a remarkable color: it has a very dark back and a very light belly, and a pattern of light stripes runs along the sides. Common dolphins are the fastest of cetaceans and feed on schooling fish. Their upper and lower jaws are equipped with sharp and almost indestructible teeth.
Killer whale. This large (8-10 m long) dolphin is easily recognized by its very high dorsal fin (up to 1.8 m in males). The killer whale is called the “killer whale.” This school predator is a thunderstorm seabirds and animals, especially seals, walruses, and dolphins. No animal, not even a huge one blue whale, these fast, strong cetaceans, which can swim at a speed of 55 km/h, will not be separated from the school. Large killer whales have few teeth, but they are large, and the jaws are equipped with strong muscles.
Grinda (ball-headed dolphin). This dolphin weighs more than 4 tons, its body length is about 8 m. It has a spherical outgrowth on its forehead, which increases with age. During the day, the pilot whale sleeps, and at night it dives 30-60 m (sometimes up to 1 km!) to catch octopuses and squid, which it eats 35 kg daily. Underwater, the pilot whale can go without air for two hours.
Among mammals, cetaceans—whales and dolphins—display the highest degree of adaptation to the aquatic environment. The shape of the body makes it perfectly streamlined. Powerful layer subcutaneous fat reduces heat transfer and prevents water pressure when animals are immersed to great depths. The cornea of the eyes is flattened, and from the harmful effects sea water they are protected by Harderian glands, which secrete a specific oily liquid. The penetration of water into the respiratory tract (blowhole) is prevented by the mouse nasal canal system. The larynx is designed in such a way that the trachea and esophagus are isolated from each other. This allows cetaceans to ingest food directly in the water. The inner ear is adapted to perceive sound and ultrasonic vibrations.
No turbulences form around a dolphin swimming in a stream of water, slowing down its movement. Such eddies - turbulent currents - greatly slow down, for example, the movement of submarines with a configuration similar to the body shape of dolphins. “Antiturbulence” in dolphins is ensured by the structure of the skin, which is penetrated by a huge number of passages and tubes filled with a spongy shock-absorbing substance.
The sea turned out to be an extremely favorable environment for the development of fine hearing in cetaceans. Sounds travel almost 5 times faster in water than in air, and over much greater distances. Many species of toothed cetaceans have sophisticated sonar, allowing them to navigate in the aquatic environment using sound signals. Animals emit specific location sounds and then pick up the reflected echo from various underwater objects. This method of orientation is called echolocation.
The sonar includes mechanisms for transmitting and receiving sound signals. The sonar transmission mechanism is very complex. The main role in it is played by air sacs, which are concentrated in the soft tissues of the head above the bony nostrils. The directionality of the echolocation beam is achieved through the coordinated work of the air sacs, nasal canal, frontal fat pad and complex system muscles. The fat pad and the concave surface of the skull focus the emitted signals and direct them into space in the form of a beam. Let's assume that the location beam meets a fish on its way. The reflected acoustic beams pass through the skin to the lowermost part of the jaw - the bone membrane, then to the intramaxillary fat pad and finally to the ear. The angle at which the sound rays strike the mandible is important. Accurate location is achieved if this angle is between 30 and 90°. It is no coincidence that dolphins constantly seem to shake (“scan”) their heads as they approach the object they are locating.
The operating principle of sonar is widely used in modern technology, for example in sonars and echo sounders.
Dolphins constantly (with a frequency of up to 1000 times per second) make sounds (whistles and clicks) to communicate with their fellows and to navigate in space using echolocation. If such a sound wave encounters an obstacle, then, reflecting from it, it creates an echo, which allows the mammal to move in the right direction, go around obstacles, and also find its prey. Dolphins “pronounce” these sounds with their nostrils. They can whistle, bark, meow, squeal, quack, chirp, and roar. Some of these sounds correspond to signals of feeding, anxiety, and fear. For example, they have special distress signals when an animal is in danger of suffocating underwater. In this case, the dolphins rush to the aid of their brethren in trouble and push him to the surface. Dolphins, placed in two separate pools, between which there is electronic communication, actively “talk”, although they do not see each other. Bottlenose dolphins are able to imitate the human voice to some extent.
All these amazing abilities of dolphins led to the 60s. XX century American neurophysiologist John Lilly came to the conclusion that dolphins have developed language, similar to human speech. Is this true? Human language has two codes - acoustic and semantic (semantic). The first is associated with the sound parameters of the word (duration, frequency modulation, etc.), the second - with semantic characteristics. With its help, a person is able to describe events of the past, present and future. Neither D. Lilly nor his followers were able to prove that the “language” of dolphins has a semantic code.
The range of sounds produced by whales and dolphins is unusually large, up to ultrasound. The time between the click-signal and the return of its echo indicates to the animals the distance to any object in their path. The unique echo-location abilities of cetaceans allow them to navigate at night, swim minefields, determine the depth of the bottom or submerged object (in some countries they even tried to use dolphins for military purposes). Cetaceans have the best developed hearing, despite their lack of an external ear. They perceive not only sounds, but also infrasounds (very low sounds) and ultrasounds (very high sounds), which lie beyond the range of human hearing. Scientists have found that during their travels, whales and dolphins are able to perfectly navigate the sea in any weather - in storms and calms, at depth and at the surface of the water, day and night. It turned out that so-called analyzers—sense organs—help them.
At one time, some scientists believed that dolphins could be taught human language, but, unfortunately, this was not achieved. At the same time, during the experiments it turned out that when experiencing different emotions, dolphins make completely different sounds. The study showed that the most important signal for cetaceans is the distress signal. Hearing the voice of a relative in trouble, they immediately rush to help. As a result, the death of one individual often ends in the death of the entire group. The infamous blowouts large groups whales ashore - the result of the instinct to preserve the species, when, having heard a cry for help, everyone rushes at once to save a relative.
Dolphins are the best acrobats among marine mammals. They love to jump out of the water, do somersaults in the air, dive again like a fish, or happily splash onto their backs. The dolphin can most often be seen in zoos and dolphinariums. He seems cute and smiling because of the special curve of his mouth line.
IN Ancient Greece The dolphin was considered a sacred animal, and many myths and legends were associated with it.

Dolphins sleep underwater, usually at night, and during the day only after feeding. A weak blow from the hanging tail from time to time forces the sleeping animal out of the water for another respiratory act. In sleeping dolphins, one hemisphere sleeps alternately, while the other is awake at this time. Underwater, dolphins navigate primarily using ultrasound in a very wide range - with a frequency of up to 170 kHz. Published by them sound signals at the ultrasound level they are reflected from possible prey, as well as from obstacles. For people these sounds are inaudible. Some dolphins, such as the bottlenose dolphin, can imitate the voice of a person. They “talk” to each other using signals with a frequency from 7 to 20 kHz: whistling, barking (chasing prey), meowing (feeding), clapping (terrifying their relatives), etc.

Dolphins are very fast and jumping animals: for example, bottlenose dolphins can reach speeds of up to 40 km/h and jump to a height of 5 m; The white-sided dolphin swims even faster - at a speed of more than 60 km/h, soars up like a candle to a height of up to 5 m, and its horizontal jump is 9 m.

Common dolphin or common dolphin (Delphinus delphis)

The common dolphin or white-sided dolphin (Delphinus delphis) has an average length of 2 m, the dorsal fin reaches a length of 30 cm, flippers - 55-60 cm and 15-18 cm (width). The animal's head occupies one fourth of the entire body. A transverse groove and a ridge behind it separate the slightly convex forehead from the not too long and straight elongated muzzle, similar to a beak and flattened both above and below. The body is spindle-shaped, rather compressed than elongated, its front part is round, and its back part is slightly compressed from the sides. The narrow and high dorsal fin is sharp at the end with a convex anterior edge and a posterior one, which resembles a sickle in shape. The flippers are attached in the first third of the body, the caudal fin is divided into two blunt blades. The skin is incredibly smooth with a glossy, almost mirror-like surface, greenish-brown or greenish-black on top and pure white below, both colors separated by a so-called sinuous line. On the white side, gray and blackish spots are visible here and there.
The common dolphin lives in the seas Northern Hemisphere, it is more playful compared to other species, and sometimes it travels upstream in rivers. Herds of dolphins can approach very close to ships and linger near them for a long time. They constantly dive and rise to the surface, they can briefly expose the top of their heads, and then disappear again into the depths. They swim very quickly and are able to keep up with even the fastest steamboat, while simultaneously performing various tricks, tumbling in the water and circling around the ship. One of them can jump out of the water and then fall headfirst, making almost no noise. Common dolphins form in schools of 10 to 100 individuals or more. The main feature of their character is sociability, the main reason for which should be considered a keen interest, and not mutual affection. People of ancient civilizations leaned towards the latter statement and praised the affection and mutual love of dolphins. Gesner spoke about this as follows: “Dolphins not only show incredible love for each other, but also for their own cubs, parents, dead comrades, as well as whales and people. The special love of dolphins for their cubs is manifested in the fact that the male and female, after mating, remain together until death and are sometimes surrounded by a large family. Dolphin parents carefully raise their children, feed them, sometimes carry them on their “beaks,” accompany them everywhere and teach them how to get food so that they can survive in the future. When white-sided dolphins gather in schools for battle, they leave all the cubs behind them; if everything is calm, then the cubs swim ahead, followed by the females, and the males bring up the rear of the school, protecting them, and even in last minute They will not leave the weakest and most defenseless. If parents become weak and defenseless, then their children will get food for them and help them swim.” Common dolphins feed on fish, crayfish, cephalopods and other marine animals. Most of all they love to hunt herrings and sardines, and with particular greed they attack flying fish. And the most fierce enemy This dolphin is not a man, but a predatory killer whale. Because people only chase dolphins if there is no other way fresh meat. In addition, people love dolphins and prefer to see them as circus performers rather than food.

more photos of dolphins

What makes dolphins save drowning people?

Of course, it is very interesting to consider dolphins so merciful (remember the song “and dolphins are kind...”?) that at the slightest opportunity they will rush to help a person in trouble. This opinion is to some extent confirmed by the hypothesis that dolphins were the ancestors of people. After all, these inhabitants of salt water are also mammals and also breathe air. The brain of dolphins is very developed and is almost as complex as the human brain in terms of complexity.
Another version explains dolphin “kindness” differently and says: stories about how dolphins saved people are by no means proof of intelligence. A number of studies show that this is just a reflex, an instinct developed by dolphins in the process evolutionary development.
Instinct helps dolphins survive, preserve their community, and help their injured relatives. When a sick or wounded mammal, barely staying afloat, comes into view of its fellows, they begin to support it near the surface of the water. Thus, the dolphin, which could drown and choke, gets the opportunity to breathe air.
Of course, such behavior is commendable, but it is instinctive and has almost nothing to do with intelligence. After all, it helps the survival of an entire species. Confirmation that saving drowning people is not humanism, but only an instinct, can be seen in cases where dolphins try to rescue a relative or person who has already died.
We do not want to offend dolphins or anyone who enjoys these intelligent marine mammals. We just tried to look at the situation more carefully. There is nothing reprehensible in the fact that the reasons that prompt us to save another creature are an instinct akin to the instinct of self-preservation or reproduction.

Dolphins and man

At sea, while on the deck of a ship, you can often see a school of several dolphins overtaking the ship. Having developed great speed under water, they simultaneously, as if on command, jump out of the water. After flying several meters through the air, the dolphins dive headfirst into the sea, only to jump out a minute later.

When you watch how dolphins frolic near the ship, you admire their beauty and dexterity. The power and grace of the movements of these record holders in swimming and jumping among sea animals is amazing.

Dolphins live in all seas associated with the ocean, including the Mediterranean, Black, Okhotsk, Japanese, White, Barents. Some freshwater dolphins live in the Amazon, Ganges, and Yangtze rivers.

Scientists count about 70 species of dolphins. Some of them are numerous and live in herds, others are more rare.

Important Feature dolphins - their swift and easy movement in the water. An adult dolphin reaches speeds of over 50 km/h. With a sudden leap, he throws his body into the air to inhale. The dolphin's high-speed swimming is facilitated not only by its streamlined body, but also by the special properties of its skin.

Dolphins have complex sound signaling. It has been established that they create and perceive ultrasounds. An accurate sonar allows them to detect objects the size of an acorn in water at a distance of up to 15 m. Thanks to echolocation, dolphins, while swimming, find food and avoid collisions with obstacles even in completely muddy water.

The life of dolphins is in many ways similar to the life of toothed cetaceans. Like whales, dolphins give birth to their young in the water. At the moment of birth, the female raises her tail high above the water, the baby dolphin is born in the air and manages to inhale air before falling into the water.

For the first hours, the baby dolphin swims like a float, in a vertical position, slightly moving its front flippers: it has accumulated a sufficient supply of fat in the womb and its density is less than the density of water.

The female dolphin carries the calf for ten months. It is born half the length of its mother's body. Like a baby whale, when a baby dolphin sucks, its lips are replaced by a tongue rolled into a tube: it covers the mother’s nipple with it, and she splashes milk into his mouth. All this happens under water: the respiratory canal of cetaceans is separated from the esophagus, and a dolphin, like whales, can swallow food under water without fear of choking. Dolphins give birth to one calf every two years. Three years later he becomes an adult. Dolphins live up to 25-30 years.

Currently, dolphin fishing is prohibited. Dolphins are increasingly attracting the attention of scientists. In recent years, many articles and books have appeared abroad and in our country, striking the imagination of readers with sensational information about the extraordinary “mental” abilities of dolphins, about their intelligence.

In the preface to the Russian edition of the book by the American physiologist J. Lilly “Man and the Dolphin,” Soviet zoologist S. E. Kleinenberg writes: “Modern work on the morphology of the brain of dolphins speaks of an unusually high organization of their central nervous system, placing dolphins an order of magnitude higher than all other mammals..."

There are often stories of cases of dolphins rescuing drowning people. In aquariums, dolphins are easily taught to swim when called and jump through hoops, play with a ball, and swim with a person. Some reports indicate that dolphins, during long-term experiments in laboratory conditions, learned to understand human speech, to carry out, for example, commands from divers and to bring the necessary tools under water to divers: pliers, a hammer, an adjustable wrench, to look for an object that has fallen into the water, etc. Further research will show the reliability of such capabilities of dolphins. scientific experiments.

Circus performances of dolphins are demonstrated in many oceanariums and dolphinariums, causing great delight among the public. Dolphins jump into paper-covered or flaming hoops, play football, move on their tails, ride a rider on their backs, “sing” in front of a microphone, ring a bell, etc.

Of the dolphins, bottlenose dolphins are the best and most fully studied. These dolphins get along easily and even breed in captivity. They are friendly towards humans, quickly learn acrobatic tricks, and perform many different exercises at a person’s command. In training, according to experts, the bottlenose dolphin is superior to dogs and monkeys.

The Roman naturalist Pliny the Elder, who lived about 2000 years ago, described such a case. In ancient times, one boy from the shore Mediterranean Sea he trained the bottlenose dolphin to come when called, fed it by hand, and she regularly transported him across the bay to school and back home. Something similar happens today. In the town of Opononi (New Zealand), a young female bottlenose dolphin visited the beach, where she played with bathers. There are known cases when dolphins drove sharks away from a person who accidentally found himself in the open sea and thereby saved him. The attitude of dolphins towards sharks is easy to explain: after all, sharks are their natural enemies, they attack dolphin calves. Therefore, it is impossible to assume that animals consciously seek to help humans: dolphins act as their instinct tells them.

Dolphins are useful animals. Residents of Mauritania use them for fishing: dolphins drive red mullet into their nets. Dolphins trained and released into the sea quickly detect schools of fish. They can be taught to explore the seabed, deliver soil samples, protect people from sharks, find sunken ships and shells with pearls. Dolphins can learn to detect ships in distress and rescue drowning people. These cetaceans serve medicine as laboratory research subjects to study cardiovascular disease, the effects of nutrition, and other problems.

These peaceful sea animals require careful and reasonable treatment. They are ready to serve people no less diligently than their land-based four-legged friend - a dog.