Just as winterbound humans head for tropical spas to get away from the cold, killer whales living off the coast of Antarctica sometimes take a break from their frigid home waters. The first satellite tagging of these 6-meter-long cetaceans at the southern tip of the globe has revealed that all five whales whose tags lasted more than 3 weeks left their normal 2°C waters and headed east of the Falkland Islands to 20°C seas off Uruguay and Brazil. One whale completed a 9400-kilometer roundtrip in 42 days. The whales swam at an ever slower rate the farther north they got, yet they never really slowed down to the speeds they swim at when hunting or taking care of young, suggesting that these trips were not for foraging or reproduction as is typical for whale migrations. Instead, the researchers suggest online today in Biology Letters, the whales go to warmer waters to rejuvenate their skin—something they can't afford to do in colder waters because the process draws warm blood away from their interiors. Seals solve the problem by climbing onto land to molt, but killer whales, lacking that ability, may need to take a trip to the spa.
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