A new study indicates that nearly all of the whales that currently swim the seas have evolved attributes that protect them from the bends.

The bends occurs during rapid decompression, such as when a diver resurfaces too quickly. Nitrogen bubbles form in blood vessels and in body tissues, and the consequences may be fatal. That’s why human divers must rise to the surface at a controlled pace.

Unique Blood Vessels

Whales, on the other hand, have evolved special characteristics over tens of millions of years that protect them from this harmful condition, according to a report on the study by Discovery News:

Lead author Brian Beatty explained … that “whale blood vessels themselves are extremely smooth-walled, preventing cavitation (bubble formation), much in the same way that bubbles in a beer have a harder time forming on the walls of a glass than a plastic cup, which is why the bubbles last longer in a glass…”

Not all whales evolved this protective trait at the same time, however. Toothed whales, a group that includes killer and sperm whales, probably would have suffered from the bends about 32 million years ago, according to researchers. That’s 10 million years earlier than their baleen counterparts.

Baleen whales, including humpback, blue, and gray whales, likely diverged from the evolutionary path of toothed whales early on, which would help to explain the great diversity among whale species.

Why Can’t We Be Friends?

In NATURE’s “Killers in Eden,” you’ll find that the killer whales and baleen whales of Eden, Australia have other differences between them — and they aren’t all biological. At the height of Australia’s whaling industry, Eden residents claim, the killers cooperated with whalers by herding migrating baleen whales into the bay and harassing them to the point of exhaustion. Finally, the human whalers would move in for the final kill. Could the stories of this remarkable partnership possibly be true?