The Mystery of the Freshwater Nerpa

The Baikal seal is a biological puzzle because it lives exclusively in freshwater. While its relatives are all Arctic marine animals, this species thrives deep in the middle of Siberia.

How this seal ended up in Lake Baikal remains one of nature's greatest mysteries. Scientists believe its ancestors likely migrated through a network of ancient rivers during the ice ages. Once the glaciers melted, the population became trapped in this massive lake, evolving into a distinct species over thousands of years. It is essentially an ocean dweller that successfully adapted to life in a landlocked mountain lake.