Video: Rolling in the Deep

The blue whale isn't known for its maneuverability. The biggest blue whales are longer than two city buses and heavier than a locomotive, and they're powered by relatively small flippers and tail flukes. But surprised scientists have now caught blue whales in the act of making full 360° rolls at high speed as they close in on their prey. To track whale movements, researchers gently placed sensor-laden suction cups onto blue whales swimming off the southern California coast. The data showed that while looking for lunch, many whales rolled onto their backs, spinning 180° in a matter of 4 to 5 seconds while speeding through the sea at 11 km per hour. Then they returned to their usual belly-down position. Why do they bother? Footage from a tiny video camera attached to one whale's back may provide an answer, the scientists say in today's Biology Letters. The video shows the whale rolling 180° by extending its flipper, then opening its jaws to engulf a patch of krill, the whale's favorite meal. Off-camera, it rolls another 180° to put itself right-side up. The researchers think these "underwater acrobatics" put the animals in the right position to gulp their food after sneaking up on the krill from below.

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