Tiny land-locked, freshwater seal mysteriously exists miles from the sea
The Baikal seal is a true natural marvel. One of the world’s smallest seals, it’s entire population is land-locked in the freshwater of Russia’s Lake Baikal. The ongoing mystery as to how the seal became trapped in Lake Baikal continues to puzzle scientists.
Whilst it is estimated that the seals have inhabited Lake Baikal for over 2 million years, the route and timing of their isolation from the sea is a mystery. One hypothesis says that Baikal seals are descended from ancestors in the Paratethys Sea, which covered south-east Europe until roughly 2-3 million years ago. An opposing idea is that the Baikal seals are of Arctic ancestry, and migrated south through a formerly connected network of rivers and lakes.
Regardless of its ancestry, the Baikal seal has evolved some amazing adaptations to its land-locked home. Reaching a maximum size of 1.5m and 80-90kg, the Baikal Seal is one of the world’s smallest seals. The seal’s eyes are surprisingly large in comparison to the body size – an adaptation to the low light conditions found under the ice. Again, they are unusually long-lived seals – often living well past 50 years and reproducing into their 40s.
The Baikal seal’s feeding habits are also pretty unusual. It can stay under water without coming up for air for over 70 minutes – whether to hunt or to avoid danger. Weirdly, in the early autumn before the winter freeze, the Baikal seal will preferentially feed on fish such as sculpin in shallow lake bays and coves. Eating this prey means the seal consumes a large amount of grit, which is thought to clean the seal’s innards and remove parasites.
Lake Baikal itself is remarkable. At 636 km long, almost 80 km wide at its widest point, with an average depth of 700 m and a maximum depth of 1.6 km, it is better termed an inland sea. Indeed, it is recognised as the world’s oldest (25 million years +), deepest and clearest lake – holding over 20% of global surface freshwater. Containing over 1,085 species of plants and 1,550 species of animals – many of which are restricted to the lake – Lake Baikal is extremely rich in biodiversity.
If you are lucky enough to visit Lake Baikal during spring or summer, you may see groups of up to 500 seals basking on the surface.
- Seal conservation society information page
- BBC news report on Lake Baikal
- Informative article at ScienceBlogs
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