Humpback whales have a specialised larynx for underwater singing

Biologists have figured out how baleen whales produce their signature songs – and it involves their uniquely shaped larynx.

Baleen whales, including humpbacks, communicate with complex songs that can be heard over vast distances. “People recorded the first whale calls in the 1970s, but it was only recently that we began to appreciate the variety of sounds these animals actually make,” he says. QUEEN ELEMENTS at the University of Southern Denmark. “Now, the question is, how do they do it?”

To learn more, Allemans and his team removed the larynxes of three recently deceased baleen whales: a sei whale (Balaenoptera borealis), a humpback whale (Megaptera noveangliae). and a northern minke whale (Balaenoptera acutorostrata).

The larynx, commonly known as the voice box, is an organ that sits at the top of the neck in mammals. When air flows through the organ, the tissue layer vibrates, resulting in sound.

Not so with baleen whales, says Allemans. Examining the whales’ larynxes, the team found they had an unexpected shape – with a cushion of fat sitting on one side of the organ.

As these whales breathe, air is pushed against the blubber, causing them to vibrate and make sounds. “We’ve never seen this in any other animal,” Allemans says. “This is quite unique to baleen whales.”

Whales can also recycle air in their lungs, which comes in handy during prolonged submersion. When they exhale through their windpipe and larynx, the air goes into a sac along the wall that returns to their lungs.

From a computer model of the larynx, the team found that baleen whales can produce frequencies up to 300 Hz at depths of up to 100 meters below the sea surface. This is within the frequency range of the noise of ships, leading to concerns that shipping noise could drown out their songs.

“These whales can’t survive that,” Allemans says. “So we need to take steps to reduce our noise.”