It’s always quite difficult to pass up a dolphin show, because where else can you see such graceful and cheerful creatures! Therefore, every year dolphinariums are opened in many cities 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?
The dolphin is a playful species that is found in many regions of the 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?
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:
But how did it happen that they changed their usual habitat to water spaces? What made them move to the new world? What is the true story of the dolphin? And are there facts to support it?
In fact, dolphins are not the only creatures that have changed one element to another. For example, the most famous case 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.
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 the later ancestors of cetaceans:
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 is beyond any doubt.
By the way, with the development of genetics, many secrets of the universe began to gradually lose ground. So, scientists have recently discovered some 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.
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.
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.
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.
Scientific classification
intermediate ranks
Domain: Eukaryotes
Kingdom: Animals
Type: Chordata
Class: Mammals
Order: Cetaceans
Family: Dolphinidae
International scientific name
Pied dolphins (Cephalorhynchus)
Common dolphins (Delphinus)
Pygmy killer whales (Feresa)
Pilot whales (Globicephala)
Gray dolphins (Grampus)
Malaysian dolphins (Lagenodelphis)
Short-headed dolphins (Lagenorhynchus)
Whale dolphins (Lissodelphis)
Irrawaddy dolphins (Orcaella)
Killer whales (Orcinus)
Beakless dolphins (Peponocephala)
Lesser killer whales (Pseudorca)
Long-beaked dolphins (Sotalia)
Humpback dolphins (Sousa)
Dolphins (Stenella)
Large-toothed dolphins (Steno)
Bottlenose dolphins (Tursiops)
Dolphins, or dolphins (lat. Delphinidae) are a family of mammals of the order Cetaceans, suborder of toothed whales (Odontoceti).
general description
Skeleton (bottom) and model (top) of a dolphin
Dolphins are characterized by the presence in both jaws of a fairly significant number of uniform conical teeth, both nasal openings are usually connected into one transverse crescent-shaped opening at the top of the skull, the head is relatively small, often with a pointed muzzle, the body is elongated, and there is a dorsal fin.
Very mobile and dexterous, voracious predators, living mostly socially, are found in all seas, even rise high into rivers, feeding mainly on fish, mollusks, and crustaceans; sometimes they attack their relatives. They are also distinguished by their curiosity and traditionally good attitude towards people.
Some dolphins have a mouth extended forward in the form of a beak; in others the head is rounded in front, without a beak-like mouth.
Dolphins swim extremely fast, schools of dolphins often follow ships, using, in addition to the “Grey's paradox” described below, the wake of ships for even greater acceleration. The dolphin has been loved and popular since ancient times: there are many poetic legends and beliefs (the legend of Arion) about dolphins and their sculptural images.
The word dolphin goes back to the Greek δελφίς (delphis), which in turn came from the Indo-European root *gʷelbh - “womb”, “womb”, “womb”. The animal's name can be interpreted as "newborn baby" (perhaps due to its resemblance to a baby or because the dolphin's cry is similar to that of a child).
Physiology
The gestation period of dolphins is 10-18 months. The female dolphin usually brings one calf 50-60 cm long and carefully guards it for some time. Dolphins apparently grow slowly, and their life expectancy should be quite significant (20-30 years). In some cases, scientists have observed that the cubs do not sleep at all for the first month of life, forcing the females to be active during this entire time. In the 1970s, a group of scientists from the Utrish sea station IPEE discovered an unusual sleep pattern in dolphins. Unlike other mammals studied at that time, only one of the two hemispheres of the brain is alternately in a state of slow-wave sleep. Perhaps the main reason for this is that dolphins are forced to rise to the surface of the water from time to time to breathe.
Brain Development
Dolphins' brains, in proportion to their body size, are much larger than those of our closest relatives, chimpanzees, and their behavior indicates a high degree of mental development. The brain of an adult dolphin weighs about 1,700 grams, while that of a human is 1,400. A dolphin has twice as many convolutions in the cerebral cortex as a human.
According to the latest scientific data from cognitive ethology and zoopsychology, dolphins not only have a “vocabulary” of up to 14,000 sound signals, which allows them to communicate with each other, but also have self-awareness, “social cognition” and emotional empathy, a willingness to help newborns and the sick , pushing them to the surface of the water.
Movement
Associated with dolphins is the so-called. "Gray's Paradox". In the 1930s Englishman James Gray was surprised by the unusually high swimming speed of dolphins (37 km/h according to his measurements). Having made the necessary calculations, Gray showed that according to the laws of hydrodynamics for bodies with constant surface properties, dolphins should have had several times greater muscle strength than was observed in them.
Accordingly, he suggested that dolphins are able to control the streamlining of their bodies, maintaining a laminar flow around them at speeds for which it should already become turbulent. In the USA and Great Britain after World War II and 10 years later in the USSR, attempts began to prove or disprove this assumption. In the USA, they practically stopped in the period from 1965-1966 to 1983, since, based on incorrect estimates, erroneous conclusions were made that the “Gray's paradox” does not exist, and dolphins only need muscular energy to develop such speed. In the USSR, attempts continued in 1971-1973. The first experimental confirmation of Gray's guess appeared.
Signals
Dolphins have a sound signaling system. Signals of two types: echolocation (sonar), which serve animals to explore the situation, detect obstacles, prey, and “chirps” or “whistles”, for communication with relatives, also expressing the emotional state of the dolphin.
Since 1942, researchers have learned that dolphins and toothed whales emit ultrasonic echolocation clicks, which they use to navigate in turbid waters. Working with the Hawaiian spinner dolphin (Stenella longirostris), whale researcher Professor Ken Norris found that by directing ultrasonic signals at schools of fish, whales can stun and sometimes even kill fish. These signals cause the fish's air-filled swim bladders to resonate so intensely that the vibration transmitted to body tissue disorients the fish. No less interesting was the discovery that dolphins can use not only very high, but also low-frequency sounds to stun prey. In 2000, Dr Vincent Janik studied the common bottlenose dolphin (Tursiops truncatus) in the Moray Firth, Elginshire. He found that bottlenose dolphins produce a characteristic sharp noise of low-frequency sounds exclusively when eating. Since dolphins themselves are insensitive to low frequencies, Zhanik suggests that dolphins produce these sound signals to stun their prey.
The signals are emitted at very high, ultrasonic frequencies that are inaccessible to human hearing. The sound perception of people is in the frequency band up to 20 kHz, dolphins use a frequency of up to 200 kHz.
Scientists have already counted 186 different “whistles” in the “speech” of dolphins. They have approximately the same levels of organization of sounds as a person: six, that is, sound, syllable, word, phrase, paragraph, context, they have their own dialects.
In 2006, a team of British researchers from the University of St. Andrews conducted a series of experiments, the results of which suggest that dolphins are capable of assigning and recognizing names.
Currently, a number of scientists are working on deciphering complex signals using the CymaScope device, designed for this purpose by the British acoustic engineer John Stuart Reid.
Dolphins are used in pet therapy to treat people using ultrasound sonar.
Representatives
Common dolphin
The common dolphin (Delphinus delphis L.) has from 100 to 200 (their number varies) small, conical, slightly curved teeth, separated by equal intervals; the snout is of moderate length separated by a groove from the slightly convex forehead. The upper side of the body and fins are grayish or greenish-black; the belly is white; the skin is very smooth and shiny. Reaches 2 m in length; dorsal fin height 80 cm; pectoral fins 15-18 cm wide, 55-60 cm long. It is found in all seas of the northern hemisphere, both off the coast and in the open sea; also enters rivers. They live in flocks of 10, 100 or more (up to several thousand) animals.
D This species of dolphins is quite common and often seen. Typically, representatives of the genus form flocks and move together. They can be seen near the shore, or accompanying ships. The size of an adult individual is about 2 m, weight is about 80 kg.
The common dolphin prefers fish as food, but if necessary, it can also feed on other marine life. When choosing fish, he will give preference to anchovy, but will not disdain octopus in difficult times.
The animal is very mobile, it can jump, as if flying out of the water, and such a flight is carried out at a distance of about 10 m. It is often on the surface, and spends less time under water in total. But there are also deep-sea representatives who hunt and live at depth, occasionally rising to the upper layers of water.
Dolphins of this species usually live in births - for example, cohabitation of several generations is often found. During the mating season, it is possible to divide into flocks based on gender. Females “in position” or young mothers may separate. Animals help each other - no matter how strange it sounds, and this makes them even more like people.
The average lifespan of dolphins is 30-35 years - this species is no different from the others. The speech of the common dolphin is varied, there are loud and strong sounds, usually the animals “whistle.” These individuals can be found in the oceans and seas almost everywhere - the population is very widespread. Reproduction of animals occurs in the warm months; the cub is born for about a year.
Appearance - body size about 2 m, elongated muzzle and dark color. A distinctive feature is the light sides and belly. The eyes and fins are highlighted. The back is dark, in the form of a “blanket”. The oral cavity contains sharp teeth, of which dolphins have about 200.
bottlenose dolphins
Bottlenose dolphins (Tursiops truncatus) are the most famous and popular species of dolphin. When you mention a dolphin, a person is more likely to imagine this particular species. Bottlenose dolphins owe their popularity partly to numerous references in cinema and fiction and their high ability to learn.
Distributed throughout the world. Representatives of the genus of bottlenose dolphins, living in the northern part of the Atlantic Ocean (occasionally entering the Baltic Sea), are less common than the previous species and reach a larger size (3.5-4.5 m in length); The Greenlanders called it “nezarnak”.
This type of dolphin is exactly the one that is well known to all of us from films, videos, etc., and each of us, probably, could see it when we were at sea. The population is very common, usually in groups of 5-10 animals. Flocks of more than 400 animals are possible - but this can only be seen at sea.
Adults measure more than 2 m in size and weigh approximately 200-300 kg. They usually choose fish as food, sometimes octopuses are used. This type of dolphin has been well studied by scientists. The animal can live either alone or in groups. It is often located near the shore, but searches for food at the bottom. The bottlenose dolphin is active during the daytime, and at night it sleeps. To sleep, the dolphin is placed on the surface of the water; it can also rest during the day, after a hearty lunch.
The animal's speech has been well studied - today certain signals can be identified, for example, when a bottlenose dolphin wants to eat, it makes sounds similar to the meowing of a cat. If she is hunting, the sound is similar to the barking of a dog; to scare away the animal cracks or clicks. There are other sounds that allow animals to communicate quite freely.
The animal can be found in almost all ocean waters, preferring warmer ones. The bottlenose dolphin breeds in the warm season and bears its young for 1 year. A pregnant female avoids other dolphins and becomes less active. The baby appears underwater and immediately rises to the surface. The female finishes feeding after about 2 years.
The appearance of a dolphin is familiar to everyone - a dark color with a light belly, a large dorsal fin, an elongated muzzle, and clear outlines. Variations in color are possible, but small. The animal has a friendly character, is highly trainable, and quickly remembers commands.
Classification
Suborder Toothed whales (Odontoceti)
1.Family River dolphins (Platanistidae)
2.Dolphin family (Delphinidae)
Genus Bottlenose dolphin (Tursiops)
Genus Common dolphins (Delphinus)
Genus Prodolphins (Stenella)
Genus Long-beaked dolphins (Sotalia)
Genus Large-toothed dolphins (Steno)
Genus Cetacean dolphins (Lissodelphis)
Genus Short-headed dolphins (Lagenorhynchus)
Genus Beakless dolphins (Peponocephala)
Genus Malaysian dolphins (Lagenodelphis)
In total, the dolphin family includes about 40 species. Of these, 11 species are found in Russian waters. Porpoises are often classified as dolphins.
Dolphins are also called species belonging to the superfamily river dolphins.
Security
Some species and subspecies of dolphins are on the verge of extinction and are protected by local and international legislation. One example is the New Zealand subspecies of Hector's dolphin known as the Maui dolphin (Cephalorhynchus hectori maui). In total, fewer than 150 of these dolphins live in the waters of New Zealand's North Island.
Since 1966, after the adoption of the CITES Convention (Appendix 2), dolphin fishing was prohibited in the USSR. Türkiye has not yet ratified this treaty.
2007 was declared by the UN as the “Year of the Dolphin” and, due to its success, was extended to 2008.
Dolphin therapy
Dolphin therapy is a method of psychotherapy that is based on communication between a person and a dolphin. It is carried out in the form of communication, games and simple joint exercises under the supervision of a specialist. It is often used in the treatment of diseases in children such as cerebral palsy, early childhood autism, attention deficit hyperactivity disorder, etc.
Fighting dolphins
Fighting dolphins are dolphins trained for military purposes. United States and Russian security agencies have trained oceanic dolphins for several tasks.
Their training included detecting underwater mines, rescuing sailors after their ship was destroyed, locating enemy combatants, and searching for and destroying submarines using kamikaze techniques.
There were even suggestions about the possibility of installing complex equipment, for example, sonar jamming devices, search devices, and so on. The U.S. Navy denies ever training marine mammals to cause damage or harm to humans or to deliver weapons to destroy enemy ships.
Captivity
A dolphinarium is a special aquarium for demonstrating trained dolphins to spectators. As a rule, large aquariums show killer whales and bottlenose dolphins, as well as performances with their participation.
Dolphins are widespread throughout the world, as they live in many oceans and seas of the planet, with the exception of the Caspian and Aral Seas. Most species are found in temperate and tropical regions, although they can live from the equator to the polar regions. They are also found in several major river systems including the Indus, Ganges and.
Obviously, the habitat is different for each dolphin species, but generally these mammals avoid extremely cold waters, which is why they are not found in polar regions.
Most of them live in salt water, but some species thrive in. Dolphin habitat varies depending on environmental factors and food availability. They are intelligent creatures with a high level of intelligence that can change their habitats when necessary for survival.
For example, bottlenose dolphins are found in all oceans, and they tend to live near coastlines. Migration is an important part of the life of some dolphin species. They must migrate to where there is enough food; This is why in some places where there used to be dolphins, there are either very few of them, or they disappear altogether. Even changes in water temperature can cause them to leave the places that once served as their home.
The Atlantic, Pacific and Indian oceans and their seas contain a large number of dolphin species due to their warm waters. In addition, some species are distributed over large areas, while others may be endemic exclusively to certain ocean regions.
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, order Cetaceans DEPENDING ON THE STYLE THE BACK OF DOLPHINS CAN IT BE BLACK, DARK brown or gray in color, 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 snout. In some species it even ends with a real “beak”, perhaps 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. A dolphin lives from 30 to 50 years in 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 reach 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 do not show any signs of decompression sickness, like in humans. This is due to the special structure of 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 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 with the help of ultrasound in a very wide range - with a frequency of up to 170 kHz. The sound signals they emit at the ultrasonic level 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 human voices. 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 up to 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.
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 underneath, 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 of the Northern Hemisphere, it is more playful than 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 in front, followed by the females, and the males close the pod, protecting them, and even at the last minute will not leave the weakest and 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 of this dolphin is not a man, but a predatory killer whale. Because people only pursue dolphins if there is no other fresh meat available. In addition, people love dolphins and prefer to see them as circus performers rather than food.
more photos of dolphins
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 of 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.
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.
An important feature of dolphins is 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 sucking a baby dolphin's 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. The reliability of such capabilities of dolphins will be shown by further research and 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, ride 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 shores of the Mediterranean Sea taught a bottlenose dolphin to swim 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.
Marine inhabitants that have attracted people's attention for centuries with their intelligence and mystery are dolphins. Their graceful, spindle-shaped body is ideal for swimming. Friendliness and curiosity have often made dolphins friends of people. There are numerous cases when these cetaceans saved the lives of drowning people.
Zoologists classify dolphins as mammals of the suborder of toothed whales. There are more than 50 species of these animals. They can be found in almost any part of the world's oceans.
Mammal skin is elastic and smooth. The back is dark brown or black, the belly is much lighter, almost white. The dolphin is able to change the elasticity of its fins and skin depending on the density of the aquatic environment. It is allowed to develop enormous speed by a specific lubricant that covers the entire body.
The pointed muzzle looks like a bird's beak. However, if you look into the mouth, you can see a large number of very strong teeth, from 80 to 100 on each jaw. This is necessary to keep prey in the water, since dolphins are carnivores.
Cetaceans breathe through a blowhole - a nasal opening located in the center of the head. Therefore, they are forced to rise to the surface quite often. During sleep, they slowly drift under the surface of the water surface, emerging every 30 seconds to breathe. This is done automatically, the dolphins don’t even wake up.
Dolphins live in large families (pods), in which all members are relatives. They don't have strangers. Family ties are so strong that clans do not disintegrate for several centuries. The pack can be led by either a female or a male, depending on the type of group. Animals “talk” using whistles or chirps, which have different emotional connotations.
Any action is performed by the group synchronously. This explains the most beautiful sight - a school of dolphins soaring above the water. Animals never leave their relatives in trouble and are able to support a weakened comrade on the surface as long as necessary so that he does not choke.
During the hunt, animals attack large schools of fish. Being in shallow water, they are able to set traps for their prey. Dolphins do not disdain mollusks and crustaceans.
Sometimes, in pursuit of fish, animals descend to a considerable depth - up to 300 m. To do this, they have to hold their breath for a long time, up to 15 minutes. Sometimes dolphins catch fish by stunning them with their tails or disorienting them through echolocation.
Depending on the species, pregnancy in dolphins lasts approximately 12-16 months. During childbirth, the mother is surrounded by her friends, protecting her from a possible killer whale attack. The female usually gives birth to one calf. Immediately after birth, the flock pushes the baby to the surface, where its lungs open.
The baby is born quite large, about 60 cm in length. During the first months, he does not swim away from his mother and feeds on breast milk right in the water. He cannot choke, since the dolphins' esophagus does not connect to the respiratory tract.
Raising offspring is the responsibility of females. Thanks to intensive nutrition, babies quickly gain weight. Cetaceans reach a state of maturity by two years.
