More than 2,000 kilometers away from the ocean, why do marine life appear in Lake Baikal?

Many people may not know that as the largest freshwater lake in East Asia, Lake Baikal has many marine creatures living in the lake. An inland freshwater lake more than 2,000 kilometers away from the sea lives with saltwater marine creatures. Kind of incredible.

In the southern part of Eastern Siberia today, there is a vast and huge lake, known as the "Pearl of Siberia", which is the world's first deep lake Baikal.

If you have listened to Li Jian's "Lake Baikal", you must not forget the melodious and melodious Russian minor in the song, and the love described in the lyrics as quiet and clear as lake water. In reality, Lake Baikal also retains too many mysteries. It is located in the southern part of Eastern Siberia and runs through the Russian Federation. The total area of ​​the lake reaches 23.6 trillion cubic meters and the total depth is 1637 meters. There is no second freshwater in the world. A lake that rivals its depth!

The origin of the name "Baikal" is also full of mystery. In ancient Evenki and Mongolian, the word "Baikal" can be translated as "ocean".

But this is strange, since ancient times, in any record of Lake Baikal in history, it is recorded as a freshwater lake. Why is such a freshwater lake named after "ocean"? Is it just because his area is so vast?

What is even more bizarre is that for a long time, Lake Baikal, a freshwater lake, has indeed been home to many marine creatures. Ferocious sharks, cute seals, lobsters and conch shells that should have been distributed in tropical waters, and in the earth There are many kinds of primitive multicellular animal sponges that have survived for 600 million years.

This special phenomenon has puzzled many geologists and biologists who have studied freshwater lakes for many years. So, what secrets does this lake hold that led to the occurrence of this strange phenomenon? ? To understand the reason, we must start with the birth of Lake Baikal!

According to the rocks and strata formed in different periods on the earth, people started from the "Cambrian" 542 million years ago, and divided the period that has passed on the earth into three geological eras, starting from the "Cambrian" By the early Triassic, collectively referred to as the "Paleozoic", during this period, ferns and crustaceans dominated the biosphere, and the entire earth was covered by the ocean. Transition to its first glorious period.

From the beginning of the Triassic to the late Cretaceous, it entered the "Mesozoic" of the earth, that is, the age of dinosaurs. During this period, amphibians appeared, and through gradual evolution, they finally moved from the ocean to the land, the sea became shallow, and more plates Exposed to the sun, dinosaurs have become the strongest overlords on the land. Various ancient plants have spread on the continent. The earth has gradually evolved from a large ocean blue to the blue-green planet we are familiar with today.

In the late Cretaceous period, a catastrophe that destroyed the sky and the earth suddenly came, completely subverting the endless world. The once-overlord dinosaur, which was equally insignificant in the face of disaster, disappeared completely in an instant and became extinct from the earth.

However, life can always find a way out. After the catastrophe, angiosperms appeared on the earth, followed by the derivation of a large number of mammals. The earth was reborn and officially entered a new era: "Cenozoic".

Having said all that, what do these geological epochs have to do with marine life in Lake Baikal?

The so-called "Cenozoic" is the latest geological era in the history of the earth. It is also composed of multiple "epochs". Now the era we are in is the "Quaternary". In this era, many biological They have all evolved into modern appearances, and the primates have also completed the evolution process from apes to humans.

The strangeness is here. Unlike most creatures that have completed the evolution of the Quaternary, many marine creatures in Lake Baikal still retain the original appearance of the Tertiary, such as the very famous Baikal seals and sharks. Wait, as long as we unravel the answer to this question, I believe we will be able to understand why this is a freshwater lake, but there are so many marine animals living here!

Today, in the Quaternary period of the "Cenozoic", why are there creatures of the Tertiary period inhabiting Lake Baikal? Does this have anything to do with the phenomenon of marine animals living in the lake?

The answer is yes, and they are very related! According to research by many geologists from the former Soviet Union, in the Jurassic period of the Mesozoic Era, the area east of Lake Baikal used to be a vast open sea, until the middle of the Cenozoic Tertiary period 25 million years ago, because India The collision between the plate and the Eurasian plate caused a strong earthquake in this sea area. The extrusion of the plate led to the formation of a lake basin. A large amount of seawater flowed into the cracks in the crust, and the continent gradually emerged from the sea. This area was formed by the earthquake. The low-lying lake basin has been left behind for a long time, until today, it has become what we know as "Lake Baikal".

Since then, marine creatures in the Tertiary have stayed in this huge low-lying area and continued to rely on lake water for survival. The seawater has gradually become thinner, so that it has completely transformed into a freshwater lake, and the marine creatures living in it have gradually adapted to the living environment from the ocean to freshwater, and thrived here from generation to generation.

Time keeps passing, 2.58 million years ago, the end of the Tertiary, the earth entered the "Cenozoic Quaternary", followed by a long glacial period.

During this period, including northern Siberia, large areas of land, mountains and rivers on the earth were covered by glaciers, and the Tertiary creatures in many waters became extinct one after another. After the ice age, after derivation and evolution, Quaternary emerging species that dominate the earth's biosphere.

But the area around Lake Baikal in Eastern Siberia was not affected by the Quaternary glaciers, so those marine creatures that originally inhabited here in the Tertiary were lucky to survive and thrive until now! This is why, even though Lake Baikal is a freshwater lake, there are still so many marine creatures inhabiting it.