Sieve-toothed seals may be whales in the making

LAKE BAIKAL, near Russia’s border with Mongolia, is, by volume, the biggest body of fresh water on Earth. At 1.6km, it is also the deepest. Several unusual animals call it home, including the world’s only species of freshwater seal.Baikal’s seals are abundant. There are about 100,000 of them. But the lake is nutrient-poor, so how they do so well has been a mystery. A study just published in the , by Watanabe Yuuki of the National Institute of Polar Research, in Tokyo, suggests the answer is by filtering tiny organisms from the water.