Potvin ([seen here] with an accelerometer on his head) has been helping the biologists build a sophisticated physical model of a feeding fin whale. They set out to build a model that would produce the kinds of behavior that real whales do. For example, a fin whale will dive hundreds of feet down in search of food. Once it gets deep enough, it speeds up dramatically, and then abruptly slows down, almost stopping. Yet even as it slows, its tail is still moving up and down, generating tremendous thrust. Then, about half a minute later, it speeds up and slows down again. What’s going on? According to the scientists, this pattern occurs when the whales lunge into a cloud of krill and drop open their jaws. Pleats under the lower jaw open up, engulfing huge amounts of water. The whale slows down because of the drag. It behaves, in other words, a lot like a parachute.
So writes Carl Zimmer in The Loom.