Scientists Discover How Some Whales Can Sing While Holding Their Breath Underwater

Scientists may have finally solved the mystery of how some whales are able to sing underwater.

Baleen whales—filter feeders that include blue whales, fin whales and humpback whales—make noises via a larynx, or voice box. Researchers understood that baleens use this organ to sing, but they weren’t sure exactly how it worked, writes National Geographic’s Melissa Hobson.

In a study published last week in the journal Nature, scientists studied three larynxes from humpback, minke and sei whales that had died after becoming stranded. They found that a fatty pad at the back of the larynx vibrates against the animals’ vocal cords to produce sound, a mechanism that has never been documented in another creature, writes the New York Times’ Kate Golembiewski.

The experiment “changes our perspective on how sounds are made in these whales,” Joy S. Reidenberg, who studies whale anatomy at the Icahn School of Medicine at Mount Sinai and did not contribute to the findings, tells the New York Times.

“This is the most comprehensive and significant study to date on how baleen whales vocalize, a long-standing mystery in the field,” Jeremy Goldbogen, who studies whales at Stanford University and was not involved in the research, tells Maria Cheng of the Associated Press (AP).

Whales make noises to identify the shapes of objects, locate food and communicate with others. Singing, in particular, is thought to play a role in mating for male humpbacks.

Toothed whales, which include dolphins, sperm whales and beluga whales, evolved a nasal vocal organ to make sounds, while baleens rely on their larynx.

But beyond this understanding, it has been difficult for researchers to study whale sound production. Whale remains often decompose too quickly for scientists to retrieve and analyze them, and studying live whales presents other complications. “You can’t just take an endoscope down a baleen whale and see what they’re doing when they’re singing,” Reidenberg says to National Geographic.

The three larynxes from beached whales offered researchers a way around this problem, and in studying these organs, the team found that the mammals had evolved unique structures for making noise.

Whales’ ancestors lived on land, so when they returned to the water, “they basically had to change the larynx, because when these animals are breathing on the surface, they need to expel lots of air really fast,” Coen Elemans, a co-author of the study and expert on voice production at the University of Southern Denmark, tells the New York Times. In the larynxes of most mammals, the vocal cords might get in the way of a massive flow of air.

Instead, baleen whales developed special tissues that form a U-shaped structure within the larynx, according to a statement from the University of Southern Denmark. This structure allows the whales to keep a rigid open airway when breathing, Tecumseh Fitch, a co-author of the study and cognitive biologist at the University of Vienna, says in the statement.

To test this, the researchers attached the three whale larynxes to pipes in the lab and blew air through them. They determined that this unique mechanism plays a key role in producing the whales’ song.

“We found that this U-shaped structure pushes against a big fatty cushion on the inside of the larynx. When the whales push air from their lungs past this cushion, it starts to vibrate, and this generates very low-frequency underwater sounds,” says Elemans in the statement.

As the fat pad vibrated against the vocal cords in the lab, it emitted the sounds of whale song, per the New York Times. This unique adaptation enables baleen whales to produce sound by recycling air—and avoid breathing in water, according to ABC News’ Julia Jacobo.

Perhaps, if the vocal cords also vibrated against each other as the fat pad vibrated—or if each cord vibrated against the pad at a different frequency—the whales could make multiple sounds at once, Reidenberg says to National Geographic.

Since the study only involved three whales, the researchers will need to look at more larynxes to reach conclusions that might more accurately represent all baleens.

Additionally, all three whales examined were juveniles, Heidi Pearson, a marine biologist at the University of Alaska Southeast who did not contribute to the findings, notes to National Geographic. Since only adult males sing, the findings will need to be confirmed with adult males, Reidenberg tells the AP.

The researchers also found that the frequency of the whale noises would likely be in the same range as noises made by shipping vessels. As a result, human activities might cover up the sounds of whales and hinder their ability to communicate, suggesting human noise at sea needs to be better regulated, according to the statement.

Whales live in a “completely acoustic world,” Sharon Livermore, who was not involved in the study and is director of marine conservation at the International Fund for Animal Welfare, tells ABC News. “Underwater noise is a pollutant, and it’s an invisible pollutant to the human eye.”

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.