Clear skin is worth some extra time -- even for a whale. In fact, some whales may leave their usual feeding grounds for weeks to clear up their skin.
Many whales found in cold polar waters have sickly looking skin. It’s covered by a slimy yellow layer of algae. But the skin of other whales in the same areas looks clear and healthy.
Whales that spend most of their time in polar waters sometimes head for the tropics. The leading ideas have said the trips provide access to better feeding grounds, or protection for calves.
In recent years, though, a team of biologists came up with another idea: the migrations are to clear up the skin. In cold waters, the whales don’t pump much blood to the skin, so they don’t shed older skin cells. That allows algae to build up. But clear skin is needed for good health. So perhaps the whales head to warmer climates to shed the old skin.
Researchers used satellites to track 62 killer whales that lived near Antarctica. And they found that many of the whales took trips northward. They went in straight lines, at more than twice their usual swimming speed, then headed straight home. They covered thousands of miles per trip.
The trips were too fast for young calves to keep up. And they didn’t last long enough for the whales to do much feeding in the warmer waters. So perhaps the trips were all about good grooming. In fact, the researchers say that other species of whales may be taking those same sorts of trips -- to keep healthy skin in cold waters.