In 1918, an interesting object was discovered in one of the freshwater lakes in the Chinese province of Hunan. In Lake Dongting, an aquatic mammal was noticed, which belongs to the suborder of toothed whales. They called this animal "Chinese river dolphin".
Who are river dolphins
People are used to the fact that dolphins are inhabitants of s alty sea and ocean waters. But there is a small family called River Dolphins. Today there are 4 species of these cetacean mammals. 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 because of the neighborhood with people. They are dying out due to pollution of rivers and uncontrolled hunting.
What is the name associated with
The local population calls the river mammal "baiji". The Chinese river dolphin has a very distinctive flag-like dorsal fin. 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 bearer". As you can see, scientists also used external associations when choosing a name for a smallspecies of mammals.
View description
The freshwater toothed whale, the Chinese river dolphin, is a fairly 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 weight of an adult animal can range from 100 to 160 kg. The description of the dolphin is not too detailed. The females of this species are known to be larger and larger than the males. The body of dolphins is dense and stocky. The neck is quite mobile. The pectoral fins have a wide base, but seem to have been chopped off with an ax towards the edge. The dorsal fin is medium in size, with smoothly rounded anterior and posterior margins. It is located not in the middle of the back, but closer to the tail.
On the top of the head of a mammal there is an oval blowhole. It is slightly off center. The Chinese river dolphin does not see well. Its eyes are poorly developed and rather unfortunately placed. They are high on the head, which reduces the viewing angle.
The anterior part of the brain skull is the so-called rostrum, it is narrow and elongated. It curves slightly upward and resembles a crane's beak. The upper jaw has fewer teeth than the lower. Maximum top is 68 teeth and bottom is 72 teeth.
It is impossible to write a description of a dolphin without specifying the color of the animal. Baiji is light blue or bluish gray in color. The belly of animals is white. Although some eyewitnesses claim that the color is much lighter than inofficial description. They say the Chinese river dolphin is almost white.
Spread the view
Most often this kind of river dolphins was found in the Yangtze River. If you have seen what the Yangtze River looks like on a map, then you can imagine how full-flowing and extended the artery is. Its length exceeds 6300 km, but even this did not save the Chinese river dolphins from the threat of extinction. Occasionally, these mammals were found in the Qiantang (river) and the lakes of Dongting and Poyang. One specimen was seen in the Shanghai area.
How the species lives and what it eats
Studying the lifestyle of this species is very difficult. Due to the small number, there is almost no information. It is only known that river dolphins keep in pairs and prefer estuaries and shallow coastal 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 practically useless, you have to rely on echolocation.
The Chinese river dolphin is diurnal. At night, he retreats to areas with a slow current to rest calmly.
Mammals eat small fish, eels, catfish and shellfish. For hunting, the animal uses a long beak. With its help, the dolphin digs out prey from the silt. To crush hard shells, he uses teeth that are specially adapted for this purpose.
Sometimes river dolphins gather in groups. Such a group may consist of 3 individuals, and may include 15 animals. But these formationslong-term.
Reproduction
There is too little information about the breeding of Chinese river dolphins. Scientists make assumptions based on bits of data they have on hand. The females are not very fertile. They bring one cub at a time and no more than once every 2 years. Most likely, the gestation period is 11 months. Cubs are born too weak. At first, the mother has to keep them afloat with her fins.
The exact date of puberty is not known. It is speculated that this may occur between the ages of three and eight.
Attempts to save the view
Of course, scientists are trying to save endangered species, but in the case of the Chinese river dolphin, success has not been achieved. Despite the fact that the species is under protection and is listed in the Red Book, there are virtually no animals left in nature. The last evidence of fishermen's encounters with this species of dolphins was received in 2004. In 2007, an expedition was sent to collect a certain number of individuals of different sexes (about 25 heads). This could allow the species to breed in captivity and partially restore the population. But the expedition returned with nothing. Modern equipment has not recorded the baiji. This leads to a sad conclusion: the population of river dolphins has died out and it will not be possible to restore it. As sad as it is to realize, the Chinese river dolphin has been officially declared extinct since 2007.
