Lake Baikal is a freshwater lake, but why are there such marine creatures as seals and sharks?

The world's great wonders. There are too many phenomena in this world that humans cannot explain with science, such as the boiling rivers in the Peruvian Amazon, the subterranean ocean, etc., and most of them seem to be related to water. There are not only marine life in Lake Baikal, but also a variety of species, so how did these marine life come to Lake Baikal?

Everyone knows that ordinary marine creatures will not appear in freshwater lakes. Not only freshwater lakes, but also some saltwater lakes do not have so many marine creatures. How do so many marine creatures survive in Lake Baikal? what about? Geologists speculate that 520 million years ago, the water in Lake Baikal was still salty, but due to the continuous inflow of rainwater and river water into Lake Baikal, the lake water began to become freshwater. In order to adapt to the environment, marine creatures also became "freshwater creatures", such as sharks and seals. They all live in Lake Baikal.

There is also a saying that as early as a long time ago, Lake Baikal was connected to the Arctic Ocean. Later, due to the movement of the crust, the two gradually separated and became what they are today, but the creatures that lived in the Arctic Ocean were left behind in Lake Baikal. , and with the continuous influx of water from the land into Lake Baikal, it has become a veritable freshwater lake.

It is true that some lakes are separated from the ocean and become lagoons due to silt blocking, and some are further gradually desalinated into freshwater lakes due to precipitation, such as Hangzhou West Lake; some lakes are blocked from the ocean by the uplifted land due to geological changes. Split out into lakes, such as the Caspian Sea. The existence of marine life in lakes derived from the ocean is well understood, but this explanation does not apply to Lake Baikal.

Everyone said: Baikal sharks are not actually sharks at all, but a kind of freshwater fish called Dufu fish; Baikal fishery is also very rich, there are more than 2000 kinds of unique freshwater lake creatures in the lake, the most is Duwen There are 25 species of duwen in the fish family, which are rich in species and have become one of the largest fishing grounds in Russia.