Devin Farmiloe: Those are the haunting melodies of baleen whales reverberating through the ocean waves. Many people across the globe are familiar with the 1970 album Songs of the Humpback Whale, produced by biologist Roger Payne. While I am a little too young to have caught its release, I remember seeing the CD for sale at Walmart alongside other calming tracks for meditation.
[CLIP: Low-pitched humpback sei whale song]
Farmiloe: You could press a button to get a preview of each album, and all of a sudden, as you stood on the concrete floors in front of a display of posters, the eerie songs of the humpback would fill your ears.
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Now scientists believe they have discovered how humpbacks and other baleen whales produce these unique sounds. Their findings, published online last month, may also explain why noise pollution from ships hinders the whales’ ability to communicate.
[CLIP: Humpback whale song fading into show theme music]
Farmiloe: Hi, I’m Devin Farmiloe, and you’re listening to Science, Quickly.
Farmiloe: Even after Songs of the Humpback Whale popularized whales’ songs and increased public awareness of the animals’ decline, they remained an enigma.
Coen Elemans: We know very little of them…. And if they beach, unfortunately, then it’s really hard to get there on time. The tissues they have decompose incredibly fast. And whales, as you know—or might know—they also have been known to explode on the beach. So you have to get there fast in order to study physiology.
Farmiloe: That’s Coen Elemans, a professor of bioacoustics at the University of Southern Denmark. He is particularly interested in how animals make sound and how their brains control it.
Since it is difficult to study whale physiology, it took Coen and his colleagues a while to find suitable specimens. When they got access to three stranded baleen whales, including two located close to their lab in Denmark, it led them to a breakthrough. First, a six-month-old sei whale died in a nearby fjord in 2018, likely because of emaciation. Then, almost a year later, a juvenile female humpback got tangled in a fishing net and drowned at the northern tip of the country.
Elemans: We were lucky, in that sense, that two animals stranded very close to the lab here in a harbor where we have very quick access. So I think one of the big breakthroughs was we actually could get fresh tissue, and then we can actually study their physiology in a way that has not been done before.
Farmiloe: With this new opportunity to examine baleen whale physiology, Coen and his colleagues were able to solve the more than 50-year mystery of the creatures’ melodies.
The human voice box, or larynx, makes sound when air passes over our vocal folds. The larynx of the baleen whale, however, needs to accommodate living underwater.
This roughly half-meter-long voice box creates sound when a fatty wedge-shaped cushion vibrates and presses on the larynx while air passes through.
[CLIP: Elemans’ team recreating baleen whale songs]
In the lab, Coen and his colleagues attached the preserved voice boxes of the dead whales to a series of pipes, blowing air into the larynxes to make them sing. While the songs weren’t as beautiful as those heard in the sea, the scientists were able to replicate the sounds of these enigmatic creatures.
Coen and his colleagues also created digital models to help them fully understand the impact of muscle movements on whale vocalizations, including how they affect frequency.
Elemans: We figured out that their voice box actually still can make sound, but it does so in a very unique way. It doesn’t have vocal folds like we have, but it has a new structure that’s got sort of a cushion with muscle in it. And when they press a rigid structure—like a hard structure—against that and blow air past it, they can still make sound underwater.
Farmiloe: This unique way of producing sound hasn’t been observed in any other animal species. It was a necessary evolutionary change that happened over the course of tens of millions of years, some time after whales’ ancestors returned to the sea following a stint as terrestrial animals. And thanks to evolution, their voice box adapted to this new environment and gave them a way to communicate under water—until humans came along and started making a ruckus.
[CLIP: Sounds of noisy boats]
Elemans: But that system also actually limits what kind of frequencies they can make and also where they can make it. So we can rather convincingly show now that they can only make this from the surface to about 100 meters deep because then they simply run out of air.
Farmiloe: Typically baleen whales sing to one another under the ocean’s surface to communicate about swimming destinations, potential dangers, food locations and other important information. Boats, however, can disrupt this chatter.
Elemans: You can see that frequency band and also the depth of vocalizations where these animals make their vocalizations sadly perfectly overlaps where we make a lot of boating noise. And so one of the consequences is that these animals have a really cool way to make sound, but they cannot make, they cannot voluntarily say, like, “Oh, today I’m going to sing a bit higher,” because they’re just physiologically constrained. And they can also not sing deeper. So they are stuck in this frequency band and depth band where we make [the] most noise.
Farmiloe: Have you ever tried to have a conversation next to rushing traffic? Noise can disrupt human communication, too, but we have many other ways of giving and receiving information, such as sight. Whales do not have that luxury.
Elemans: They use sound for almost all their communication because on the water, you cannot see anything. So they use sound to find each other to coordinate movement and migration. So it’s really important for them.
Farmiloe: Decades after whale songs first played on record players across the world, inspiring a new wave of conservation, the hidden anatomy behind these melodies has been brought to the surface. Whale songs are now ubiquitous. They can be played in your living room, your car—even in an aisle of a Midwestern Walmart. But whales do not live on land anymore; they live in an increasingly noisy ocean, one that is drowning out their songs.
Science, Quickly is produced by Jeff DelViscio, Rachel Feltman and Kelso Harper and edited by Timmy Broderick, Elah Feder and Alexa Lim. Music is by Dominic Smith.
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For Science, Quickly, this is Devin Farmiloe.