Who would have guessed that whales could be lazy? Or maybe they are just really smart.

Bryde’s whales, which for some reason is pronounced broo-dess, have been seen treading water in one place, just like swimmers do in the deep end of the pool. While treading water, the whales have their mouths open right at the surface of the water to suck in fish or other small animals.

Bryde’s whales are what’s known as baleen whales. Think of baleen as having bristles, like a toothbrush, instead of teeth. The whales usually swim through a school of small fish with their mouths open and then squirt the water back out through the baleen. That way they get a big gulp of fish and no water.

Most baleen whales do that “lunge” type of feeding. But scientists have for the first time recorded the Bryde’s whales treading water to get their fill of food in a bit more lazy way.

When you think about it, treading water for a 45-foot long, nearly 9,000-pound whale can’t be all that easy. So maybe they need to relax once in awhile too. Or, the scientists think, the whales may be changing their behavior to adapt.

Where the whales were seen feeding on the surface the water has less oxygen. The scientists think this may drive the small fish to the surface, where there’s more oxygen. Since the fish are schooled below the water, the whales had to find a new way to get their fill of fish. So now they do what the scientists are calling tread-water feeding.

— Brett French, french@billingsgazette.com