In 1918, an interesting object was discovered in one of the freshwater lakes in the Chinese province of Hunan. In Dongting Lake, an aquatic mammal, which belongs to the toothed whale suborder, was spotted. They called this animal "Chinese river dolphin."
Who are river dolphins
People are used to the fact that dolphins are inhabitants of salty sea and ocean waters. But there is a small family called River Dolphins. Today there are 4 species of these cetaceans. Three of them live in fresh water, and the fourth can live both in rivers and lakes, and in the ocean. Unfortunately, these are endangered species of animals. They suffer greatly due to their proximity to people. They are dying due to river pollution and uncontrolled hunting.
What is the name associated with
The local population calls the river mammal "baiji". The Chinese river dolphin has a very characteristic dorsal fin, similar to a flag. This is what gave the colloquial name to the whole species. The scientific name of the species is Lipotes vexillifer. It includes two concepts. Leipo means “forgotten” and vexillifer means “flag carrier”. As you can see, scientists also used external associations when they selected a name for a small species of mammals.
View description
The freshwater representative of the toothed whale, the Chinese river dolphin, is a rather large animal. The maximum recorded body length of a mammal was 2.5 m. And the minimum length of an adult is 1.5 m. The mass of an adult animal can range from 100 to 160 kg. Dolphin description is not too detailed. It is known that females of this species are large and exceed the size of males. The body of dolphins is dense and stocky. The neck is quite mobile. The pectoral fins have a wide base, but they are chopped off with an ax to the edge. The dorsal fin flag is medium in size, with smoothly rounded front and rear edges. It is located not in the middle of the back, but closer to the tail.
On the crown of the mammal there is an oval-shaped respiratory tract. It is somewhat offset to the left of the center. The Chinese river dolphin is hard to see. His eyes are poorly developed and rather poorly positioned. They are located high on the head, which reduces the viewing angle.
The front part of the brain skull is the so-called rostrum, it is narrow and elongated. It bends slightly upward and resembles a beak of a crane. The upper jaw has fewer teeth than the lower. The maximum number on top is 68 teeth, and on the bottom 72 teeth.
It is impossible to write a description of a dolphin without specifying the color of the animal. Baiji is a light blue or bluish-gray hue. The tummy in animals is white. Although some eyewitnesses claim that the color is much lighter than in the official description. They say that the Chinese river dolphin is almost white.
Species distribution
Most often, this species of river dolphins was found in the Yangtze River. If you saw what the Yangtze River looks like on a map, you can imagine how much this is a full-flowing and extended artery. Its length exceeds 6300 km, but this did not save the Chinese river dolphins from the threat of extinction. Occasionally, these mammals were found in Qiantang (river) and Lakes Dongting and Poyanghu. One individual was spotted in the Shanghai area.
How the species lives and what it eats
To study the lifestyle of this species is very difficult. Due to the paucity, there is almost no information. It is only known that river dolphins stay in pairs and prefer river mouths and coastal shallow waters. Most likely, this is precisely the reason for the poor development of the organs of vision in the species. The water here is always cloudy, so the eyes are virtually useless, you have to rely on echolocation.
The Chinese river dolphin leads a daytime lifestyle. At night, he leaves for sections with a slow course to rest in peace.
In the diet of a mammal, small fish, eels, catfish and shellfish. For hunting, the animal uses a long beak. With its help, a dolphin digs prey from silt. For crushing strong shells, it uses teeth that are specially adapted for these purposes.
Occasionally, river dolphins gather in groups. Such a group may consist of 3 individuals, and may number 15 animals. But these formations are not long-term.
Breeding
There is too little information about the breeding of Chinese river dolphins. Scientists make assumptions based on grains of data that they have in their hands. Females are not too prolific. They bring one cub each and not more than once every 2 years. Most likely, the gestation period is 11 months. Cubs are born too weak. At first, the mother was forced to keep them afloat with her fins.
The exact puberty is not known. According to assumptions, this can occur between three and eight years.
Attempts to preserve the view
Of course, scientists are trying to save endangered species of animals, but in the case of the Chinese river dolphin, success was not achieved. Despite the fact that the species is under protection and is listed in the Red Book, there are virtually no animals in nature. The latest evidence of fishermen meeting with this species of dolphins was obtained in 2004. In 2007, an expedition was sent to collect a number of heterosexual individuals (about 25 animals). This could allow to breed in captivity and partially restore the population. But the expedition returned with nothing. Modern equipment did not fix baiji. This leads to the sad conclusion: the population of river dolphins has died out and it will not be possible to restore it. It is regrettable to realize this , but since 2007, the Chinese river dolphin has been officially recognized as an extinct species.