Planet Earth

Study: Killer Whales Migrate Thousands of Miles to...Exfoliate?

DiscoblogBy Veronique GreenwoodOct 27, 2011 9:50 PM

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Before: scuzzy yellow (top); and after: pearly white! (bottom)

Killer whales are best known for their picturesque profiles and predilection for seal flesh, but they also like to travel

, a recent study confirms. And these aren't your basic joyrides through ice flows. These are 6,200-mile excursions to the tropics, where scientists speculate they engage in a pursuit familiar to anyone who's headed to a Bermuda spa in February: getting rid of that wintry dead skin. To get detailed information about whales' movements, a group of scientists equipped whales with tags that would record swim velocity and current location. At first they just noodled around the Antarctic hunting, a behavior the scientists could identify from the bursts of speed they put on as they went after prey. But then, each in their own time, they started to rocket northwards, moving nonstop until they reached the balmy waters hear Uruguay and southern Brazil, nearly 6,000 miles away. Then, just as suddenly, they whipped around and came back. One whale made the trip in just 42 days. These trips didn't happen at any particular time of year, nor did they seem to involve mating or following traveling prey, and those high speeds imply that they weren't stopping much to eat. The researchers suggest that one explanation for the journeys is that the whales have to get to warmer waters before they can shed their worn-out, outer layers of skin and grow fresh ones---the Antarctic is so frigid that removing a protective layer there could be dangerous. And before and after photos make a strong visual point: this whale is definitely whiter after its trip to tropics than before. Maybe they get together with these sponge-wielding dolphins

and loofah each other up. Cuter things (though not many) have happened

.

Images courtesy of John Durban / NOAA via San Diego Union Tribune

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