Some whales double their weight when straining sea-water

How do giant whales get so big eating such little krill? By using their baleen like a parachute and sucking in their body-weight in water in one go, then straining it out:

Since then, Potvin has brought his expertise on parachute physics to these parachuting whales. He and the other scientists have developed a sophisticated new model that tracks the incoming water more carefully. It's a lot of water, the scientists have found: in one lunge, a fin whale can momentarily double its weight.

If a whale simply let the water come rushing in, there would be a tremendous collision-more than a whale could handle. Instead, the scientists argue, the whales actively cradle their titanic gulp. As the water rushes in, the whales contract muscles in their lower jaw. The water slows down and then reverses direction, so that it's moving with the whale. (It just so happens that fin whales do have sheets of muscle and pressure-sensing nerve endings in their lower jaw. Before now, nobody quite knew before what they were for.) Once the water is moving forward inside the whale it can then close its mouth and give an extra squeeze to filter the water through its baleen.

The Origin of Big

(via Kottke)