Baikal water has more oxygen than human blood, and its transparency is such that you can see 40 meters deep. There are about 2600 different kinds of living creatures in the lake, two thirds of them are not found anywhere else on the planet.
ENDEMICS
The largest freshwater reservoir of the planet is also the deepest. According to various estimates, its depth is around 1600 meters. There are very few dissolved and suspended mineral substances and organic impurities in it, but a lot of oxygen.
There is an abundance of living organisms due to the high content of O2 in the pond, most of which are unique (endemics). These include absolutely all nematodes, worms, sponges, isopods and Plecoptera, living in the lake, more than half types of the fish (59%) and aquatic mammals.
Even the viruses of Lake Baikal are unique. In 2016, researchers at the Limnological Institute of the Siberian Branch of the Russian Academy of Sciences discovered and described several previously unknown species of autochthonous bacteriophage viruses that do not occur in other levels of the world's ecosystems.
PLANKTON WITH TEETH
The unique purity of water Baikal owes it to the invisible for eyes crustaceans - epishure (Epischura baicalensis), which make up to 80 percent of all crustaceans in the lake. By eating bacteria and unicellular algae, these crustaceans, with the help of several pairs of mouth limbs, create a current of water and at the same time, something like a filter net to catch food particles in a stream. One individual purifies about a glass of water this way.
Another feature of the epishura, which was discovered not so long ago, is strong silicon teeth, capable of cracking the hard shell of diatoms, the beloved food of these animals. The tooth (more precisely, a special crown) is placed on one of the teeth of the jaws (mandibles) of these crustaceans. Over time, crowns are grinding or breaking, but new ones grow in their place.
The fish Omul'
The Baikal epishura serves as feed to another endemic - Baikal omul (Coregonus migratorius), a fish of the salmon family that lives only in the lake and adjacent rivers. The length of the omul - from 30 to 60 centimeters, weight - from 250 grams to one and a half kilograms.
Scientists have been arguing for a long time about how and when this fish appeared in Baikal. According to one version, 20 thousand years ago it swam into the lake from the rivers flowing into the Arctic Ocean. But there was another hypothesis: the omul is a descendant of pelagic (that is, living in the water column) whitefish from the reservoirs of Siberia, not associated with oceanic waters. The question was resolved by a genetic analysis that showed that the omul is a relative of the modern whitefish and has nothing to do with oceanic fishes.
There are discussions now about the number of omul - and again all hopes for genetic analysis. Scientists of the Limnological Institute of the SO RAN in March 2018 took one hundred water samples in different regions of Lake Baikal and at various depths in order to decipher in the near future the traces of the DNA of the lake inhabitants contained in it. These results will allow us to judge the diversity of animals and their distribution in the lake.
Comephorus and the strange way of reproduction
Limnologists hope to learn more about the golomyanka (Comephorus baikalensis and Comephorus dybowski), unlike other fish species, it is impossible to study golomyanka with the echosounder, since it does not have a swim bladder.
It also does not have squama, and its body contains 35% of fat. Another feature of this fish is that it does not lay eggs, giving birth to fry at once, up to two thousand at a time. In other words, eggs develop in the mother's body. To activate their growth, according to the scientists, sperm even from a fish of a different kind is enough. Fertilization itself does not occur, therefore, all the newly born babies are actually clones of their mother. This method of reproduction is called gynogenesis and is extremely rare in nature.
Golomyanka lives in the water column, down to the most bottom layers. At night, it goes up closer to the surface, in the daytime it goes to depths of up to 500 meters. This fish accounts for up to 75% of the entire biomass of the lake, it is part of the diet of the only water mammal of the Baikal-seal (Nyerpa, Pusa sibirica).
Mysterious Baikal-seal
The Baikal-seal, like the golomyanka, has approached non-standard approaches to reproduction issues - in unfavorable conditions, it can suspend pregnancy. The embryo stops development, but it does not die and does not collapse, but falls into anabiosis lasting three to five months. This method of regulating pregnancy is very rare and is known only in 0.05% of mammals. Nerpa is already mastering it by the age of four or seven, when it reaches puberty.
This animal perfectly swims under the water, accelerates to 25 km/h and dives to a depth of 200 meters. Sometimes for half an hour the seal undergo a pressure drop from one to 15 atmospheres, but this does not lead to caisson disease. The animal does not breathe underwater, which means that the saturation of tissues and blood with gases remains the same, which corresponds to atmospheric pressure.
There are different opinions about the appearance of seals in Lake Baikal. Some scientists believe that this animal swam into the lake from the Arctic Ocean several thousand years ago (on biological grounds the Baikal seal is close to the ringed one, inhabiting the seas of the Far North and the Far East). Others believe that the entire family of true seals, namely the Baikal seal, was originally formed in the large fresh water reservoirs of Eurasia and only then settled into the Caspian Sea and the Arctic Ocean.
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