In which country can you find river dolphins. Where can you see dolphins in Russia in their natural habitat? What dolphins drink

In the suborder of toothed whales, the family river dolphins- 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 terms of lifestyle and outwardly, differs from the well-known sea dolphins.

Characteristics of the animal

If you compare river dolphin with a marine brother, it will become clear that the freshwater one is more primitive.

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

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

Bouto or Amazonian inya

First Amazonian initiative described in detail French scientist D "Orbigny. Traveling around Peru, he caught this freshwater dolphin and studied its appearance well.

The natives do not hunt for others. Why?

The natives ignore the yew due to the fact that the meat of these river dwellers is not solid, and there is almost no fat. Also the reason v a large number mysterious stories related to the animal. According to one of them, the Amazonian inya is an evil sorceress, capable of transforming into a young beautiful woman with curly curls. 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 depths of water with his admirer.

Fat can be used to fill lamps, but no one does it. Belief says that a person who does this will go blind or he will be in trouble.

Pliny about the freshwater dolphin

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

Susuk lifestyle and structure

• The body of this river dolphin is slender.
• The dorsal fin is semilunar and divided into two lobes, essentially a fold of skin.
• Slightly raised, long, thin, beak-shaped muzzle, equal in 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 held the susuk in captivity for 10 days, showed that these animals rise for a moment to the surface of the water every half a minute to take a breath.

They feed on crayfish and fish. Pregnancy is expected to last 8-9 months; into the light one cub appears, for a long time Remaining under maternal care, it clings to its dorsal fin with its muzzle.

Susuk is rarely hunted, mainly for meat. This meat is especially eaten. indian women who have childbirth difficulties. According to legend, meat helps to get pregnant and carry a child safely. Monks and pilgrims, considering the animal sacred, feed it by hand.

Chinese dolphin

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

Laplat River Dolphin

• Can live in rivers and seas.
• The body length of males reaches 1.55 m. In females, the body length can reach 1.7 m.
• Weight - 28-35 kg.
• The emerging cubs are about 45 cm long.
• The snout is long.
• Skin color is pale brown.
• The number of teeth is 210–240.
• Eats fish, crayfish and cephalopods for food.

The Laplatan dolphin is sociable, willingly swims up to fishing boats, makes contact with humans. Live these miniature dolphins at the mouth of the La Plata River and the coastal waters of Brazil, Argentina and Uruguay (between 30 and 45 ° S lat.).

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 the first breath.

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

Often, the female becomes pregnant again without completing the lactation process. 5–25 months pass between mating.

Life expectancy is 16-24 years.

Chinese river (lake) dolphin is one of the rarest species mammals of our planet. Life cycle of this amazing kind animal is very brief.

First talked about in 1918, found in Dongting Lake. And already in 2006, without finding a single individual, river dolphins were declared as an extinct species. A year later, according to an eyewitness and according to the video footage, it was possible to fix one mammal in the long river our mainland Yangtze, where in last years these dolphins have found their final resting place. Previously, he lived not only in these waters, but also inhabited the vastness of the Tsentang River, Poyang Lakes and Dongting Lakes.

The appearance of a Chinese dolphin

A graceful mammal of light gray color, the abdomen of which shimmers with silvery - white shades. The stocky bodies of dolphins do not exceed two and a half meters, and their body weight can range from forty-two to one hundred and seventy kilograms.

Moreover, males are noticeably smaller than their chosen ones. A feature of this species is a narrow and very long rostrum, reminiscent of the beak of a crane. Has thirty-four on the top and thirty-six on the bottom pairs of teeth. It is characterized by poor eyesight.
Lifestyle

Chooses a place to live in the mouths of tributaries, near islands and in shallow waters. Oriented in muddy water thanks to echolation. Dolphins are active during the day, and spend the night in places with slow currents. The Chinese river dolphin hunts mainly for mollusks and small fish, but does not refuse and.

He himself has no enemies in nature. It was possible to see dolphins in pairs, and sometimes in a group of up to sixteen individuals. It can dive for a short time, only up to twenty seconds. For a given species in summer time migration into shallow channels was characteristic, and in winter it returned to its former places.

Due to given view poorly studied, unfortunately, the reproduction process, life expectancy and much more will remain a mystery to us.

To study this unique view attempts were made to keep the lake dolphin in captivity. Unfortunately, even close to natural conditions did not lead to success.

Superfamily River dolphins

These amazing aquatic animals (lat. Platanistidae) belong to the class Mammals, the order Cetaceans and the suborder Toothed whales. The considered superfamily consists of four existing in modern world families that represent four species of the same name:

Chinese River Dolphins (Lipotidae)

As a species, these animals were first discovered in 1918 in China's freshwater lake Dongting, about a thousand kilometers from the mouth of the Yangtze River. Their body weight is about 120 kg, and their length is up to 2.30 m. Like most other species of dolphins, Chinese river dolphins have an anti-shade color - a gray back with sides and a light belly. The snout (beak) is very elongated and slightly bent upward. Vision is poorly developed, like in most other species.

Keep in small groups of 3-5 individuals, sometimes up to ten to twelve. They mainly feed on different kinds benthic fish and molluscs, whose hard shells are crushed with their strong teeth with lateral outgrowths that give the dolphin's teeth the shape of an anchor. Finding food for themselves, they dig with their long beaks in the silt at the bottom of the reservoir, looking for worms with mollusks and catching lurking eels with catfish. Much about their behavior and lifestyle currently remains a mystery.

Ganges Dolphins or Susuki (Platanistidae)

Representatives of this species are capable of producing breathing sounds characteristic of the species, which served as the reason for the name of the species. Today, only a small population of these dolphins has survived. This species of river dolphins is very different from their counterparts in appearance and reaches about 2.5 m in length. Gangetic dolphins have an unusual fan-shaped pectoral fins, with five ridges and expressive anti-shade coloration (dark gray back and sides, light underside).

These animals live in the slow-flowing freshwater rivers of India and Pakistan: the Ganges, Indus, Brahmaputra and Hoogli, as well as in the tributaries of these rivers (usually in the upper reaches). Sometimes, during the rainy season, they can descend into the mouths of rivers, but never enter the sea. Susuki can stay under water continuously for about two minutes. It is interesting that the eyes of the Gangetic dolphins, or rather the corneas of the eyes, perform not a visual, but a tactile function, since in connection with the benthic lifestyle, these mammals have lost their eye lenses, and their optic nerves have completely atrophied;

Amazonian dolphins (Iniidae)

These mammals are also called Inii, or otherwise Bouto lives in large South American rivers: Tocantins, Amazon, Orinoco, as well as in their many extended tributaries of Venezuela, Colombia, Brazil, Peru, Bolivia and Guiana. During periods of flooding of these rivers, Amazonian dolphins can freely swim among the flooded trees and swim across, thanks to such floods from one river basin to another. The body length of these animals can reach up to 2.5 m and weight up to 130 kg. Sexual dimorphism is well expressed: males are much larger and more massive than females. The color of yiny varies depending on the age and place of their habitat.

Young individuals are painted in a pale grayish color, older ones acquire anti-shade, very beautiful color - light blue above, and white or pinkish below. Dolphins living in rivers are, as a rule, lighter than lake dolphins. Both of them live either alone or in small groups. Their beak is rather long, decorated with rigid bristles and has a cylindrical shape somewhat bent downwards. Their long jaws are equipped with two rows of strong teeth, the number of which can range from 104 to 132 units. Despite the fact that the eyes of these mammals are very small, unlike the eyes of other species of river dolphins, they see well. Inyes lead an equally active lifestyle, both during the day and at night, and feed on crabs and various species freshwater fish... These dolphins are very sociable and gullible towards people. Unusual and mysterious behavior in Lately is carefully studied and analyzed by scientists in various aquariums around the world.

La Plata Dolphins (Pontoporiidae)

This is the only family and species of the four considered, which can inhabit not only rivers, but also in the sea. These animals are widespread at the mouth of the La Plata River (from which they got their name), as well as in the coastal waters of Argentina, Brazil and Uruguay. Unlike other considered species, these mammals lead a nomadic lifestyle, migrating in small flocks for the winter, from the mouth of the La Plata along the coast of the mainland to the north.

La Plata dolphins feed on various types of fish, both river and sea, including herring, as well as cephalopods and crayfish. In size, these animals are relatively small - up to 170 cm long and weighing up to 35 kg., And their newborn cubs are just crumbs, whose length is only 45 cm. An interesting fact is that the females of these river dolphins are noticeably larger than males. The La Plata dolphins are dyed light brown, and their narrow and very long snout can hold up to 240 teeth! Dolphins belonging to this species are as sociable with humans as the Amazonian dolphins, however, very little has been studied so far.

I would like to note that river dolphins are almost on the verge of extinction. This happens for several reasons: firstly, from the fact that these aquatic mammals are losing their habitats, secondly from the fact that people continue to hunt them at the present time, and thirdly, because of extremely weak eyesight, they are faced with people and various artificial objects, despite the presence of a special organ of sound detection - sonar.

Origin story

The superfamily River dolphins are considered the oldest of all modern toothed whale mammals. It appeared on our planet during the Miocene period in the ocean, and in later periods it was displaced large predators and competing species. The ancestors of modern river dolphins are considered by biologists to be ancient toothed whales - squalodonts (Latin Squalodontidae), which, in turn, descended from terrestrial mammals - mesonichids.

According to the found ancient remains, the mesonchids lived about 60 million years ago and shook a very strange, according to modern concepts, appearance, reminiscent of a wolf with hooves. These strange-looking creatures lived in the territory in which the Mediterranean Sea and part of the Asian subcontinent are now located. From ancient toothed whales - squalodonts, modern river dolphins inherited primitive outward signs that distinguish them from other aquatic mammals: a very narrow elongated snout, wrinkled single-apical teeth of different sizes, fewer convolutions of the brain, very wide and short pectoral fins, and instead of a dorsal fin there is a low elongated ridge. The head of river dolphins is very mobile and is able to turn at an angle of 90 ° in relation to the body, which is facilitated by special structure cervical spine.

Other parts of the skeleton are also significantly different from the structure of other modern aquatic mammals and have a form characteristic of ancient extinct dolphins. The sight of these dolphins is poorly developed, and the main sense organs that serve to obtain information about the world around are well-developed organs of touch and an echolocation apparatus that perceives a wide range of sound frequencies. River dolphins' additional organs of touch are not only numerous skin receptors, but also tough, very sensitive tactile hairs located on the snout, which facilitate hunting in water and foraging by digging it out of bottom muddy sediments.

This is where I would like to end the story about river dolphins, but put not a full stop, but a comma, because in the future we will return more than once to these amazing, sociable and "philanthropic" creatures, but already of other species.

Amazonian inia, or bouto (Inia geoffrensis). Young animals are light gray, but gradually acquire a pinkish tint with age. Their very long snout is covered with stiff hairs or bristles, apparently performing a sensory function. Amazonian frogs have an average of 25–27 teeth on each side of each jaw. The front teeth are pointed, conical, and the back teeth are somewhat similar to the molars. Two types of teeth and non-fused cervical vertebrae- characters primitive for cetaceans. Inya feeds on fish, including those covered with bony plates, and her teeth are often severely worn out, apparently due to the chewing of solid food.

According to some reports, inia can have several subspecies. These freshwater cetaceans are common in the basins of the Amazon and Orinoco rivers, and during floods they even penetrate into flooded forests, where they swim between trees. When looking for food at the bottom, inia often turn belly upside down, possibly because their thick cheeks would otherwise obstruct their view. Studies of the sounds they make have shown the presence of a rich repertoire of impulse signals, including echolocation, used for foraging and research. environment; however, no monotonal whistles were found.

Ganges dolphin, or susuk (Platanista gangetica), lives in Indian rivers Indus, Ganges and Brahmaputra. Obviously, he is blind, since his eyes are devoid of a lens. However, animals compensate for this deficiency by developing an unusual cup-shaped depression in the skull, which resembles the enlarged reflector of a flashlight and undoubtedly directs and concentrates echolocation signals. Studies of several living specimens of this species have demonstrated their apparently exceptional echolocation abilities. The Ganges Dolphin is believed to feed on freshwater shrimp and fish burrowing into the silt, which he catches, probing the bottom with his very long jaws. Surprisingly, this animal usually swims on its side.

The Laplatan dolphin (Pontoporia blainvillei) is unique among the Platanistidae species for several reasons. He dwells not only in large river La Plata in South America, but also leaves it in purely sea coastal waters... Some features of his skeleton are also unusual and good development dorsal fin. Some taxonomists have suggested attributing it to the Delphinidae family. This small dolphin feeds on fish, shrimp and cephalopods.

Freshwater dolphins differ in that their cervical vertebrae are separated, like in land mammals, and not fused into a single bone. Some species of this family, in addition to conical teeth, have molar teeth, i.e. close in structure to the indigenous. The dorsal fin is usually very low, ridge-like; only in the Laplat dolphin it is the same as in the dolphin.

(China). This is a cetacean white with a flag-like dorsal fin, due to which locals called him "baiji" (白 鱀). Scientific name of the genus Leipo means "forgotten"; species vexillifer- "carrying the flag". In 2006, the expedition did not find this species. In August 2007, a Chinese resident videotaped a large white animal swimming in the Yangtze River.

Since 2017, the China Extinct Animals Commission (CEC) has declared the species extinct.

For a long time this species was attributed to the family Platanistidae; now they are singled out as an independent family Lipotidae.

Collegiate YouTube

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Appearance

It is a light bluish gray dolphin with a white belly. Body length 1.4-2.5 m, weight 42-167 kg. Females are larger than males. The body is stocky. The neck is mobile. The pectoral fins are wide, as if chopped off at the end. Dorsal medium height, gently sloping, located slightly behind the middle of the body. Exposed from the water, it resembles a flag. The rostrum is very long, narrow, slightly bent upward, reminiscent of a crane's beak. The breath is oval, shifted to the left. The lower jaw is white, the upper jaw has a white edge. Teeth are 2-3 pairs more than that of the susuk (62-68 above and 64-72 below). Unlike other river dolphins, the eyes lake dolphin strongly reduced, located high on the head; vision is very weak. By outward appearance closest to the Amazonian yiny.

Spreading

It was distributed in the central-eastern part of China in the river. Yangtze and the lower reaches of the river. Qiantang, as well as Dongting Lakes and Poyang Lakes. Rarely observed below Nanjing; only 1 time in the Shanghai area. A special international expedition that took place in November-December 2006 stated that the Chinese river dolphin, most likely, has completely disappeared [ ] .

Lifestyle

Ecology is practically not studied. They keep at the mouths of tributaries, near islands and in shallow waters, in muddy water, where vision is practically useless. Therefore, these dolphins have very poor vision and rely mainly on echolocation. In the Yangtze, lake dolphins swim in shallow waters only to hunt for fish. By way of life, the river dolphin is close to inia. Daytime lifestyle, rest at night in areas with a slow current. It feeds mainly on small fish, in particular on eels and catfish, which it digs out of the bottom silt with its long beak, as well as on mollusks. Dives for only 10-20 seconds. It crushes shells of mollusks with its strong teeth, which have lateral outgrowths on wide roots. River dolphins are usually found in pairs, which sometimes merge into groups of 3-16 individuals, staying in feeding places for 5-6 hours. The wounded dolphin makes a sound similar to the cry of a buffalo calf. Seasonal migrations were noted: in the lake. Dongtinghu late autumn, during the rainy season, dolphins migrated from the lake up the rivers flowing into it; in the Yangtze in the summer with high water they swam into shallow channels, in winter they returned to the main channel of the river. The longest recorded migration was over 200 km. By nature, the river dolphin is secretive and shy.

Reproduction

Reproduction is practically not studied. Apparently, it is seasonal. Breeding peaks in February-April. Pregnancy is estimated to last up to 11 months. The female brings one cub 80-90 cm long every 2 years. It is known that the cubs of the lake dolphin are very weak and practically cannot swim, therefore at first the female holds them with flippers, which was also observed in a number of other cetaceans. The duration of lactation is unknown; Dolphins reach sexual maturity between 3 and 8 years of age. Life expectancy is unknown.

Population status

The Chinese river dolphin is one of the rarest mammals on Earth. Since 1996, its status in the International Red Data Book is "critically ill" ( Critically endangered). Until 1900, its population was estimated at 3000-5000 individuals; in 1980 - 400; in 1990 - 200. In 2007, the Chinese river dolphins were officially declared extinct. [ ]

According to paleontological excavations, river dolphins migrated to the Yangtze from