Chinese river dolphin. Freshwater or river dolphins (Platanistidae) Where river dolphins live

Dolphin is one of the most mysterious and interesting mammals living on our planet. It has been known since ancient times that these mammals can save drowning people and disperse the oculi that gather near a person.

In particular, dolphins love children. The main advantages of this species of mammals are their benevolence, sociability or the desire to establish any contact with a person. Today we will discuss the topic of where do dolphins live what they eat and how captivity weakens them.

How and where do dolphins live?

The habitat of dolphins can be called the places where they live. Their place of residence can be found in any area the globe. Here, everything will depend on the type of dolphin, some of them can only live in certain places. One type of dolphin is bottlenose dolphin or simply big dolphin .

Bottlenose dolphins are very common and can be observed in many places. A fairly large number of bottlenose dolphins are found in the waters of the Pacific, Indian and Atlantic Oceans, they can be seen in such seas as the Mediterranean, Red and, of course, Black. The habitats of various types of dolphins can be near the coastline, or right in the ocean shelf zone.

Migration of dolphins, which is associated with the search for an additional source of food, seems to be a frequent occurrence. In the same case, if in any area there is enough food for these mammals, then they take root there for a very long time.

For example, consider bottlenose dolphins. They are almost always close to the coastline and rarely migrate. It depends on the amount of food near the shore, and most often it is there in great abundance. Bottlenose dolphins are exactly the type of dolphins that many people are used to imagining. Bottlenose dolphins can often be seen near the coastline, and this type of dolphin can also be seen in almost all dolphinariums. Many people who do not think about this issue may get the impression that all dolphins live exactly like bottlenose dolphins, but this is an erroneous opinion.

In fact, many dolphins are subject to migration, especially those that live in the ocean shelf and have a completely different habitat. Most often, they travel in flocks and choose the right routes to find the right water temperature and enough food for themselves. Dolphins have the ability to swim hundreds of kilometers to find a source of food.

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Dolphin nutrition

Most often, dolphins look for fish of such breeds as food, such as:

• mackerel
• mullet
• cod
• herring, etc.

Sometimes, when there is no fish, they feed on squid. The diet of dolphins will depend entirely on what kind of fish is available in the area, as well as in what season they migrated here.

Dolphins can live not only in various seas and oceans, but also "their habitat", there may be captivity, i.e. various dolphinariums. Never before has man been presented with so many opportunities for open communication with these mammals. Here you can touch them, feed them and, of course, swim with them. But people, most often, simply do not understand how dolphins themselves suffer in these conditions, because many of them were caught and thus torn out of their natural habitat.

Dolphins are smart enough and have high level intelligence, which is very difficult to develop in captivity. Scientists have long shown a lot of evidence that keeping dolphins in captivity causes them great suffering and greatly reduces their life expectancy. So, in the wild, a dolphin can live up to 50-60 years, and in captivity, its life expectancy will be reduced to 30 years.

Currently, many organizations have been created that promote the protection of dolphins and are ardent opponents of all existing dolphinariums.

Now you know how and where do dolphins live! We hope that the information provided was of interest to you.

Everyone knows wonderful animals - sea dolphins, always smiling and incredibly smart, but few people know that dolphins also live in rivers.

River dolphins are the most ancient family of modern toothed cetaceans. It appeared in the Miocene and spread widely in the ocean, but was forced out by competitors and enemies into the rivers.

ONCE A NUMEROUS POPULATION OF RIVER DOLPHINS, living in major rivers Asia, now on the verge of extinction, experts warn World Fund for protection wildlife(WWF). Human activity is to blame - the construction of dams and water pollution.

River dolphins look different from marine species more primitive features inherited from their ancestors - squalodonts. They have fewer convolutions of the brain than other dolphins, they have a narrow snout and a long mandibular symphysis.

Members of this family are relatively small. Their body length reaches 1.5-3 m, and their weight ranges from 40 to 123 kg. Females are somewhat larger than males. River dolphins do not live long, up to 30 years. They live mainly in rivers and their mouths. They are distributed in the rivers Indus, Ganges and Brahmaputra, Amazon, Orinoco, in Dongting Lake in China. River dolphins feed on fish and freshwater crustaceans. These animals get fish, mollusks and worms not only in the water, but also dig them out of bottom muddy sediments. Therefore, their beak, seated with hard tactile hairs, has hypersensitivity and vision is impaired. But all river dolphins have well-developed hearing and echolocation apparatus - the main sources of information about the space around them. Like other dolphin species, river dolphins hunt and communicate using echolocation, a process that involves detecting the low frequency waves emitted by all living things. They can perceive frequencies up to 200 kHz. River dolphins usually keep alone or in small groups. The reproduction of these animals is almost not studied.

Five species of freshwater dolphins are known. The pink dolphin lives in the Amazon and Orinoco and can be found in the waters throughout most of the river basins of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela. It is the most common species of cetaceans in fresh water.

Another species lived in the rivers of China. The Yangtze river dolphin, or baiji, was declared "functionally extinct" in 2006. Large-scale development of the country's main waterway, overfishing, an increase in the number of ships and serious water pollution have led to a progressive deterioration of the river ecosystem, which has led to the virtual disappearance unique look. The Chinese river dolphin is believed to be the first cetacean to become extinct as a result of human activity. History of extinction fluctuations in last years Chinese river dolphin allows you to put the blame for his disappearance on a person.

DOLPHINS OF THE GANGES RIVER CAN ONLY LIVE IN FRESH WATER, they are practically blind. Today, the population is divided by dams into isolated groups. Closely related to the Ganges dolphins are the Indus River dolphins, which, like the Ganges dolphins, are endangered. A hundred years ago, these subspecies lived along the entire length of this 3500-kilometer river. Today, about 1100 individuals live on the 1375 km section of the Indus River, divided into isolated populations six dams. Interestingly, local peoples use many names to refer to the Gangetic and small Gangetic (Indian) dolphins. Basically, these are words that imitate the sound made when inhaling.

Another representative of this family - the Laplata dolphin - lives at the mouth of the river of the same name, as well as in the adjacent sea ​​waters. This is the only river dolphin that goes out to sea. The life of Laplata dolphins is associated with seasonal migrations: in winter time some individuals leave La Plata and roam along the coast South America. Judging by observations and accidental catches, in the sea they live mostly in warm coastal waters at a depth of up to 30 meters.

Dam building, fishing nets, boats and pollution environment caused a sharp decline in the dolphin population over the past few decades. Today a few Asian species river dolphins are recognized as the most vulnerable of all cetaceans. Urgent action is needed to preserve them.

First, dolphins are dying from industrial and agricultural waste that is dumped into rivers. Scientists have found residues of pesticides and chemicals in animal tissues. Secondly, people also dump garbage into rivers, build dams that limit natural environment habitats for dolphins and breeding grounds for the fish that these animals feed on. The problem is further exacerbated by the increasing withdrawal of water from river reservoirs. Thus, only 5% of the water from the Ganges reaches the sea.

ACCORDING TO SPECIALISTS, RIVER DOLPHINS ARE THE MOST IMPORTANT INDICATOR OF THE HEALTH OF RIVERS. This is believed not only because the decrease in the water level in the rivers affects the dolphins. They feed on those fish that react to the quality of river water and live only in clean water bodies.

But WWF experts are concerned not only with the problem of the conservation of this species of dolphins. The disappearance of river dolphins speaks of the potential danger that threatens people in the event of a decrease in the quantity and quality drinking water. Experts are confident that what will help save the population of river dolphins will ultimately help millions of Asians living along the banks of the largest rivers.

In the suborder of toothed whales, the family of river dolphins is the most ancient. Initially, its representatives lived in the ocean, but due to stronger competitors and numerous enemies, they moved to freshwater reservoirs. The river variety, both in its way of life and outwardly, differs from the well-known sea dolphins.

Characteristics of the animal

If we compare river dolphin with a marine counterpart, it will become clear that freshwater is more primitive.

Family freshwater dolphins represent two monotypic genera living in tropical South American rivers, and two genera inhabiting Indian and Chinese rivers.

Now let's talk about the species of river dolphins known today.

Bowto or Amazonian inia

The first Amazonian inia described in detail French scientist D "Orbigny. Traveling around Peru, he caught this freshwater dolphin and studied his appearance well.

The natives don't hunt frost. Why?

The natives ignore ini due to the fact that the meat of these river dwellers is not solid, and there is almost no fat. Also the reason a lot mysterious stories associated with animals. According to one of them, Amazonian inia this is an evil sorceress, able to transform into a young beautiful woman with curly locks. In this guise, she lures gullible youths and destroys them.

Locals say that the sorceress appears in the city of Aigues, where she is looking for another victim. When she captivates the beauty of a man, leads him to the river bank, where he hugs the victim, screams loudly and disappears into the water depths with his admirer.

Fat can fill lamps, but no one does. Belief says that a person who does this will go blind or misfortune will befall him.

Pliny on the freshwater dolphin

The ancient naturalist Pliny was the first to describe another river dolphin, the susuku. Although the descriptions contained many inaccuracies, because he could observe the animal only in the water. The main misconception was in the information about the length of the body. According to the philosopher, it reached 7m. In fact, freshwater was no longer than 2 m.

Susuk lifestyle and structure

• The body of this river dolphin is slender.
• The dorsal fin is lunate and divided into two lobes, essentially a fold of skin.
• Slightly raised, long, thin, beak-shaped muzzle, the same width along the entire length.
• The upper jaw has a ridge surrounding the long and narrow nostrils.

Susuk lives in the basins of the rivers of Southeast Asia and the Indus. An experiment conducted by the biologist Anderson, who kept the susuk in captivity for 10 days, showed that these animals rise to the surface of the water for a moment every half a minute to take a breath.

They feed on crabs and fish. Pregnancy is expected to last 8-9 months; into the world one baby appears, remaining under maternal care for a long time, he clings to her dorsal fin with his muzzle.

Susuk are rarely hunted, mainly for meat. Especially willingly this meat is eaten. indian women who have difficulty in childbearing. According to legend, meat helps to get pregnant and bear the child safely. Monks and pilgrims, considering the animal sacred, feed it from their hands.

Chinese dolphin

The Chinese river dolphin became known less than a hundred years ago, in 1918. The animal was discovered in a freshwater lake, and it differed from the already studied marine species.

Laplata river dolphin

• It can also live in rivers and seas.
• The body length of males reaches 1.55 m. In females, the body length can reach up to 1.7 m.
• Weight - 28-35 kg.
• The hatchlings are about 45 cm long.
• The snout is long.
• Skin color is pale brown.
• The number of teeth is 210–240.
• It eats fish, crayfish and cephalopods.

The Laplata dolphin is sociable, willingly swims up to fishing boats, makes contact with a person. live those miniature dolphins at the mouth of the La Plata River and the coastal waters of Brazil, Argentina and Uruguay (between 30 and 45° S).

reproduction

The river dolphin reaches sexual maturity at the age of about 5 years. Pregnancy lasts 11 months. After the birth of the cub, the female pushes him out of the water so that he takes his first breath.

The length of the cub is 75–85 cm, and it weighs about 7 kg, the body is light gray in color. After the birth of the young, the male return to the river, and the female remains with the offspring in place (in valleys, channels). Females protect cubs from predators, lack of food, aggression of foreign males. Cubs stay with their mother until about three years of age.

Often the female becomes pregnant again without completing the lactation process. There are 5–25 months between matings.

Life expectancy is 16–24 years.

Dolphins are marine mammals that belong to the suborder of toothed whales. They are found in the seas and oceans, as well as rivers that have access to the sea. They feed, as a rule, on crustaceans, mollusks, fish, and some do not disdain sea ​​turtles and birds.

Where do dolphins live?

The habitat of the dolphin 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, as well as in large freshwater rivers(Amazonian river dolphin). These mammals love space and move freely over long distances.

Description

The length of dolphins ranges from one and a half to ten meters. The smallest dolphin in the world is Maui, which lives near New Zealand: the length of the female does not exceed 1.7 meters. major inhabitant sea ​​depths is considered a white-faced dolphin with a length of about three meters. The largest representative is the killer whale: the length of males reaches ten meters.

It is worth noting that males are usually ten to twenty centimeters longer than females (the exception is killer whale dolphins - here the difference is about two meters). They weigh on average from one hundred and fifty to three hundred kilograms, killer whale - about a ton.

Back sea ​​dolphins it comes in gray, blue, dark brown, black and even pink (albino) colors. The front of the head can be either solid or white (for example, the white-faced dolphin has a beak and the front of the forehead white color).

In some species, the mouth is rounded in front, the beak-shaped mouth is absent. In others, small sizes, the head ends in an elongated mouth in the form of a flattened “beak”, and the mouth is shaped so that people watching them seem to be always smiling, and therefore they often have an irresistible desire to swim with dolphins. At the same time, even a huge number of teeth of the same cone-shaped shape does not spoil the impression - dolphins have about two hundred of them.

Due to the elongated body and smooth, elastic skin, these animals almost do not feel water resistance during movement. Because of this, they are able to move very quickly ( average speed dolphin is 40 km / h), dive to a depth of about one hundred meters, jump out of the water nine meters in height and five in length.

Another unique feature of these marine mammals is that almost all species of dolphins (with the exception of the Amazonian river dolphin and several other varieties) see well both underwater and above the surface. They have this ability due to the structure of the retina, one part of which is responsible for the image in the water, the other - above its surface.

Since whales and dolphins are relatives, like all representatives of cetaceans, they are quite capable of staying under water for a long period. But, they still need oxygen, so they constantly float to the surface, showing a blue muzzle and replenishing air supplies through a drawbar, which overlaps under water. Even during sleep, the animal is fifty centimeters from the surface and, without waking up, swims out every half a minute.

Dolphin species

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

• White-bellied dolphin (black dolphin, Chilean dolphin) (lat. Cephalorhynchus eutropia) lives exclusively on the coast of Chile. An animal with a rather modest size - 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 have grey colour, while the throat, belly area and parts of the flippers adjacent to the body are absolutely 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 the Chilean authorities.

• Common Dolphin ( common dolphin) (lat. Delphinus delphis). The length of a marine animal often reaches 2.4 meters, the weight of a dolphin varies between 60-80 kilograms. In the back area, an ordinary dolphin is painted dark blue or almost black, the belly is white, and a spectacular yellowish-gray stripe runs along the light sides. This species of dolphins lives in the waters of the Mediterranean and Black Seas, feels at ease in the Atlantic and Pacific Oceans. There is a common dolphin on the east coast of South America, along the coast of New Zealand and South Africa, in the seas of Japan and Korea.

• White-faced dolphin (lat. Lagenorhynchus albirostris) - a large representative of cetaceans with a body length reaching 3 meters and weighing up to 275 kg. Distinctive feature The white-faced dolphin has a 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 capelin, saffron cod, flounder, herring, cod, whiting, as well as mollusks and crustaceans.

• Large-toothed dolphin (lat. Steno bredanensis). The body length of this marine mammal 2-2.6 meters, weight varies from 90 to 155 kg. Height dorsal fin is 18-28 cm. The color of the dolphin is dominated by gray, over which whitish spots are “scattered”. This species of dolphin is common off the coast of Brazil, in the Gulf of Mexico and California, lives in warm waters Caribbean and Red Seas.

• Bottlenose dolphin (large dolphin or bottlenose dolphin) (lat. Tursiops truncatus). 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 the habitat, but basically the species has a dark brown upper body and a grayish-white belly. Sometimes there is a weakly pronounced pattern in the form of fuzzy stripes or spots 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.

• Broad-faced dolphin (beakless dolphin) (lat. Peponocephala electra) common in the waters of countries with tropical climate, especially mass populations live along the coast of the Hawaiian Islands. The torpedo-shaped, light gray body of the animal is crowned with a cone-shaped dark gray head. The length of a mammal often reaches 3 meters, and an adult individual weighs more than 200 kg.

• Chinese dolphin(lat. Sousa chinensis). This representative of the genus of humpback dolphins lives in the waters along the coast. South-East Asia, but migrates during the breeding season, therefore 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 dolphins are born absolutely 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.

• Irrawaddy dolphin (lat. Orcaella brevirostris). A distinctive feature of this species of dolphins is the complete absence of a beak on the muzzle and a flexible neck, which received mobility due to several skin and muscle folds behind the head. The color of the body 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 tone lighter. In length it aquatic mammal reaches 1.5-2.8 meters with a weight of 115-145 kg. The habitat of the dolphin covers the waters of warm indian ocean, starting from the Bay of Bengal and up to the northern coast of Australia.

• Cruciform dolphin (lat. Lagenorhynchus cruciger) lives exclusively in the waters of the Antarctic and subantarctic. The color of the dolphin is black and white, less often - dark gray. A spectacular white marking, covering the sides of the mammal, stretches to its muzzle, framing the eye area. The second mark runs along the back of the body, intersecting with the first and forming a pattern in the form hourglass. An adult cruciform dolphin has a body length of about 2 meters in length, the weight of a dolphin varies between 90-120 kilograms.

• Killer whale (killer whale) (lat. Orcinus orca)- a mammal that belongs to the dolphin family, a genus of killer whales. The male killer whale has a length of about 10 meters and a weight of around 8 tons. Females are smaller: their length reaches 8.7 meters. Pectoral flippers of killer whales have a wide oval shape. Killer whale teeth 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 is white stripe. There are white spots above the eyes. Sometimes there are completely black or white individuals in the waters Pacific Ocean. The killer whale lives in all waters of the oceans, except Sea of ​​Azov, Black Sea, Laptev Sea and East Siberian Sea.

Dolphin Speed ​​Mystery

In 1936, the British zoologist Sir James Gray (Sir James Gray) drew attention to the enormous speed (up to 37 km / h, according to him), which dolphins manage to develop. Having produced necessary calculations, Gray showed that, according to the laws of hydrodynamics, it is impossible to achieve such a high speed with the muscle strength that dolphins possess. This riddle is known as the Gray paradox. The search for its solution to one degree or another continues to this day. AT different time Various research teams have put forward various explanations for the phenomenal speed of dolphins, but there is no unambiguous and universally recognized answer to this question yet.

Ability to regenerate

Dolphins have an incredible ability to heal themselves. In the event of any injury, even big size“They don’t bleed or die from infection, as one might think. Instead, their flesh begins to regenerate at a rapid pace, so that after only a few weeks, a deep wound, such as from a shark's teeth, leaves almost no visible scars. Interestingly, the behavior of injured animals is practically no different from normal. This gives reason to believe that nervous system dolphins are capable of critical situations block pain.

Why don't dolphins freeze underwater?

Finally, let's find out why dolphins, being warm-blooded, do not freeze in water. Their body temperature is 36.6 degrees. AT northern seas Animals need to keep warm. Water, which conducts heat up to twenty-five times more efficiently than air, allows you to freeze much faster than in air.

Why do dolphins do such miracles?! This is due to the large layer of fat under the skin. They can control their circulation and metabolism. This makes it possible to support normal temperature body, according to wikipedia.

How do dolphins breathe?

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

How Do Dolphins Sleep?

Dolphins also have another interesting physiological feature A: They never sleep. Animals hang in the water column, periodically rising to the surface for breathing. During rest, they are able to alternately turn off either the left or the right hemisphere of the brain, that is, only one half of the dolphin's brain sleeps, while the other is awake.

How are they born?

Do you know how dolphins are born? The bottlenose dolphin bears a baby for about a year. He is born tail first. The eyes of the cub are immediately open, and the senses are as developed as possible. Moreover, the barely born dolphin already has enough coordination to follow in the footsteps of the mother, who helps to rise to the surface. Then follows the first breath in the life of a baby dolphin. Such trusting relationship in a baby dolphin with a mother, they last approximately 3 to 8 years.

Dolphins and humans: who is smarter?

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 and made films), that a legend gradually emerged about the unusual high intelligence dolphins; one could often hear that they were not dumber than a man only their minds are different.

The brain of an adult dolphin weighs about 1700 grams, while that of a human weighs 1400. The dolphin has twice as many convolutions in the cerebral cortex. At the same time, there are relatively few neurons in a cubic millimeter of its substance (less than in the brain of primates).

The results of research on the behavior and physiology of the dolphin brain are highly controversial. Some put their learning ability at about the level of a dog and show that dolphins are very far from chimpanzees. In contrast, studies of dolphin communication methods lead to the conclusion that we have not yet come close to understanding this form of life in vivo and comparing the level of intelligence of dolphins and chimpanzees is simply incorrect.

One property of the dolphin brain is quite unique: it never truly sleeps. Sleep - alternately - then the left, then the right hemispheres of the brain. The dolphin needs, from time to time, to float to the surface to breathe. At night, the awake halves of the brain are responsible for this, in turn.

Dolphin communication

Dolphin language can be divided into 2 groups:

• Sign language(language of the body) - various poses, jumps, turns, various ways swimming, signs given by the tail, head, fins.
• The language of sounds(proper language) - sound signaling, expressed in the form of sound pulses and ultrasound. Examples of such sounds can be: chirping, buzzing, screeching, grinding, clicking, smacking, creaking, clapping, squeaking, roaring, screaming, screaming, croaking, whistling.

The most expressive are whistles, which dolphins have 32 types. Each of them can denote a specific phrase (pain signals, alarms, greetings and a call to me, etc.). Scientists have studied the whistle of dolphins using the Zipf method and obtained the same slope coefficient as that of human tongues, i.e. carrying information. AT recent times found in dolphins 180 communication signs who are trying to systematize, compiling a dictionary of communication of these mammals. However, despite numerous studies, it has not yet been possible to fully decipher the language of dolphins.

Dolphin names

Each dolphin has its own name, to which it responds when relatives address it. This conclusion was reached by American scientists, the results of which were published in the Bulletin National Academy US Sciences (PNAS). Moreover, the experts who conducted their experiments in US state 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 made by these mammals in the process of their communication with each other. Then, with the help of a computer, “names” were isolated from the records. When a name was "played out" for a pack, a specific individual responded to it. The "name" of a dolphin is a characteristic whistle, average duration which is 0.9 seconds

official recognition

The Government of India recently removed dolphins from the animal category and gave them the status of "non-human beings". Thus, India became the first country to recognize the presence of intelligence and self-awareness in dolphins. In this regard, the Ministry of Environment and Forestry of India has banned any performance using dolphins and called for respect for their special rights.

1. There are 43 species of dolphins. 38 of them are marine, the rest are river inhabitants.
2. It turns out that in ancient times dolphins were terrestrial, and only later adapted to life in the water. Their fins resemble legs. So our sea friends might once have been land wolves.
3. Images of dolphins were carved in the desert city of Petra, Jordan. Petra was founded as early as 312 BC. This gives reason to consider dolphins as one of the most ancient animals.
4. Dolphins are the only animals whose babies are born tail first. Otherwise, the baby may drown.
5. A dolphin can drown if a tablespoon of water enters its lungs. For comparison, a person needs two tablespoons to choke.
6. Dolphins breathe through an adapted nose, which is located at the top of their head.
7. Dolphins can see with the help of sound, they send out signals that travel long distances and bounce off objects. This allows the animals to judge the distance to the object, its shape, density and texture.
8. Dolphins are superior bats with its sonar capability.
9. During sleep, dolphins stay on the surface of the water to be able to breathe. For control, one half of the animal's brain is always awake.
10. "The Cove" won an Oscar as documentary about the treatment of dolphins in Japan. The film explores the theme of cruelty to dolphins and the high risk of mercury poisoning from eating dolphins.
11. It is assumed that hundreds of years ago, dolphins did not have such an ability to echolocate. It is a quality acquired with evolution.
12. Dolphins do not use their 100 teeth to chew food. With their help, they catch fish, which they swallow whole. Dolphins don't even have chewing muscles!
13. AT Ancient Greece Dolphins were called sacred fish. Killing a dolphin was considered sacrilege.
14. Scientists have found that dolphins give themselves names. Each individual has its own personal whistle.
15. Breathing in these animals is not an automatic process, like in humans. The dolphin's brain signals when to breathe.

The family of river dolphins is the oldest in the suborder Toothed whales. Initially, its representatives lived in the ocean, but later stronger competitors and numerous enemies forced them into freshwater rivers.

general characteristics

The river dolphin, when compared with its marine relative, is more primitive. The brain has fewer convolutions. Short and wide pectoral fins, the absence of a dorsal fin (instead of it there is an elongated crest), a very narrow snout, a long symphysis of the lower jaw - all these are features of its ancient ancestors, squalodonts.

The free arrangement of the cervical vertebrae allows river dolphins to turn their heads 90° in relation to their bodies. They feed on fish, mollusks and worms, which are mined not only in the water. With the help of a snout covered with a layer of hard tactile hairs, they are able to feel prey in the depths of the muddy bottom and dig it out. Unlike touch, their eyesight, on the contrary, is quite weak. But the hearing and echolocation apparatus are very developed. It is with their help that river dolphins receive information about the world around them.

If we talk about the range, then it can be called relic and broken. The family is represented by two monotypic genera inhabiting the tropical rivers of South America and two genera inhabiting the rivers of India and China. Next, consider the species of river dolphins discovered to date by zoologists.

Amazonian inia, or bowto

First detailed description The Amazonian inia was given by the French scientist D "Orbigny, who, traveling around Peru, was able to catch this animal and study its appearance.

The body length of the inia can reach 3 meters, and weight - 70 kg. It lives in the Amazon, Rio Negro, Orinoco basins. This dolphin can be called a real freshwater whale. It is slow (speed does not exceed 10 km / h), in muddy water an echolocation apparatus and a sensitive snout help him navigate. The main type of food small fish. This river dolphin very often comes up to the surface to inhale oxygen. Inii live only in small communities, no more than 5-6 individuals.

The muzzle is very elongated, blunt at the end and covered with bristles, looks very much like a beak. The upper and lower jaws contain 66-68 teeth each. They are very sharp, and the crowns are large and curved back. The semilunar shape of the flippers, the division of the caudal fin into blades, the low location of the adipose fin are typical features of the Amazonian inia. Top part her body is pale blue, while the underside is reddish pink. Elderly dolphins can be almost white. Therefore, the inia is often called the "white river dolphin".

Why the natives don't hunt the Amazonian ini

The natives never chase the frosts. The reason for this is the fragile meat and the almost complete absence of fat. Another thing is that many mysterious stories are associated with them. According to one of them, the Amazonian inia is actually an evil sorceress who can take the form of a young beautiful woman with long curly curls. In this form, she lures inexperienced gullible youngsters in order to then destroy them. According to local residents, she takes to the streets of Aigues to find another victim. And when she captivates a man with her beauty, she takes him to the river bank. There she takes the victim into her arms, publishes shout and disappears with the admirer in the watery depths.

The fat of these river dolphins can be used in lamps for burning, but no one does. There is a belief that a person who decides to take such a step will go blind or some kind of misfortune will happen to him.

Discovery of Pliny

The ancient naturalist Pliny first gave a description of another species of river dolphins - the Gangetic dolphin (susuku). And although there was a lot of inaccurate information in his descriptions, since he saw susuk only in water, it was this scientist who first drew attention to characteristics animal. The main delusion of Pliny was the information about the length of the body of the Gangetic dolphin. According to him, it reached 7 meters. In fact, it is no more than 2 meters.

The external structure and lifestyle of the susuk

This animal of the River dolphin family has a very slender body, a semi-lunar dorsal fin divided into two lobes, a long, thin, beak-shaped muzzle slightly raised upwards, which has the same width along the entire length. typical feature is the presence on the upper jaw of a ridge surrounding long, narrow, adjacent nostrils. Instead of a dorsal fin, there is only a small fold of skin. In the upper part of the body, the skin is colored grayish-black, and in the lower part it is grayish-white.

Susuk lives in the river basins of Southeast Asia, in particular in the Ganges, Brahmaputra and Indus. In an experiment conducted by a biologist named Anderson, who kept the Gangetic dolphin in captivity for 10 days, it turned out that representatives of this species rise to the surface of the water very often (every 30 seconds), but only for a moment, because in order to take a breath, they only need a fraction of a second.

They feed mainly on fish and crabs. Presumably, the pregnancy lasts 8-9 months, one cub is born, which for a long time remains under the care of the mother, clinging to her dorsal fin with its muzzle.

The dolphin is caught extremely rarely, mainly for the sake of meat. Indian women who experience difficulties with childbearing, eat it especially willingly. According to legend, it helps to get pregnant and carry the child safely. Pilgrims and monks, on the contrary, consider this animal sacred and feed it from their hands.

Chinese lake dolphin

This animal species became known in 1918, when a dolphin was first discovered in the waters of the freshwater lake Dongtinghu in China, which differs from previously discovered and already studied species. The body length was about 2 meters, weight - more than 120 kg. The dorsal part is gray, towards the belly the color brightens and turns into white. Pectoral fins wide enough, and their free end seems to be chopped off. Vision is very poor. These dolphins usually swim in flocks of 3-4 individuals, and in rare cases - of 10-12. The dorsal fin has characteristic shape, resembling a flag sticking out of the water. The dolphin feeds on eels, catfish, molluscs, catching prey from the silt.

Laplata river dolphin

Of all the representatives of its family, this is the least specialized species in terms of structure and lifestyle. It can live both in rivers and in the seas. The body of males in length reaches approximately 155 cm, and the body of females is somewhat longer and can reach 170 cm. The body weight is small: from 28 to 35 kilograms. Cubs are born very small: approximately 45 cm in length. Thus, these are the smallest river dolphins. Where do Laplata dolphins live? They inhabit the mouth of the La Plata River and coastal waters Brazil, Uruguay and Argentina (between 30 and 45° S).

Their skin color is pale brown. The snout is very long, the number of teeth varies from 210 to 240. They serve as food different kinds fish (herring, silver mullet, croaker fish), crayfish and cephalopods. The Laplata river dolphin is very sociable. It is known that individuals very willingly approach fishermen's boats and make contact with humans.