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For some whales, sonar may provoke suicidal behaviour: study

Scientists have long known that some beaked whales beach themselves and die in agony after exposure to naval sonar, and now they know why: the giant sea mammals suffer decompression sickness, just like scuba divers.  At first blush, the explanation laid out Wednesday by 21 experts in the Proceedings of the Royal Society B seems implausible.  Millions of years of evolution have turned whales into perfectly calibrated diving machines that plunge kilometres (miles) below the surface for hours at a stretch, foraging for food in the inky depths.  The heart rate slows, blood flow is restricted, oxygen is conserved.  So how could the ocean's most accomplished deep-sea diver wind up with nitrogen bubbles poisoning its veins, like a scuba novice rising too quickly to the surface?  Short answer: beaked whales—especially one species known as Cuvier's—get really, really scared.  Read more...



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