Mystery of whale songs revealed: Scientists discover how marine mammals' tunes travel miles through the ocean

Whales have many talents, but perhaps their most unique and mysterious one is their hauntingly beautiful singing. And scientists finally know how they do it.

The secret is a unique voice box that vibrates fat and muscle to produce sounds, rather than blowing air through it.

Singing underwater presents a difficult problem because, theoretically, it would use up all your air.

But according to a new study from an international team of scientists, whales evolved a voice box that is different from most other mammals'.

It also provides insights into the limited vocal range of the whales, something that can leave them vulnerable to having their sounds drowned out by ship engines and other human noise. 

A humpback whale breaches near Bering Island, Kamchatka. Humpack whales and other baleen whales produce sound by recirculating air through a unique structure in their throat

Whales have even been observed learning complex songs from each other.

The new study is small, conducted with just three whales, but for the first time it provides an answer to how the world's largest animals' songs can travel for miles through the ocean. 

READ MORE: Humpback whale song recorded off the coast of New York

A humpback whale surfaces near the Statue of Liberty in this photo taken from a boat on New York Harbor in December 2020. 

Until now, scientists didn't know exactly how these ocean giants could accomplish their signature feat. 

The untimely demise of three whales gave scientists the opportunity to probe the vocal anatomy of the animals.

Dead whales used in the study died of either natural causes or accidents, the scientists behind the study wrote.

A male sei whale was found near Denmark, and though its cause of death was uncertain, the scientists described it as emaciated. 

A female humpback whale probably drowned after being tangled in fishing gear, and the female minke whale likely died from a bacterial infection, the researchers wrote.

These whales are all baleen whales, different from toothed whales.

Baleen whales feed by filtering water through giant comb-like plates that catch marine invertebrates and small fish. 

To find out how the whales make sounds, the team, led by Coen Elemans of the University of Southern Denmark, dissected each animal's larynx and blew air through it to see what would happen.

What they found was that the whale voicebox does not that work in the same way as a vocal cord.

The study was published in the journal Nature.

This painting of a humpback whale indicates the cartilages of the animal's pharynx, part of the structures that produce sound

Instead, a U-shaped piece of tissue vibrates against fat and muscle structures in the whale's throat.

Blowing air through these structures in the laboratory produced the deep, resonant sounds that whales are famous for.

And its unique anatomy enables whales to recycle air while singing - as well as avoid inhaling water. 

It was 'super-exciting' to figure this out, Elemans told BBC News. 

Three young humpback whales swim with a diver. Baleen whales' special vocal structure lets them sing for long periods of time without having to breathe - and without drowning

The song of whales travel long distances, but they can be drowned out by boat engines and other human activities

'This is the most comprehensive and significant study to date on how baleen whales vocalize, a long-standing mystery in the field,' Jeremy Goldbogen told The AP. Goldbogen, who is an associate professor of oceans at Stanford University, was not involved in the study. 

These results open up doors for future study, he said, 'given the extraordinarily diverse acoustic repertoires,' of whales.

Sadly, the research also shows how vulnerable the animals are to human activities.

A computer analysis of the vocal structures showed that there is a narrow frequency range of sounds the whales can make, which leaves them vulnerable to disruption.

Since ships and other human activity produce noise that's in the same range as whale song, and since whales use their songs to find mates, human activity can make it hard for whales to find each other and reproduce.

'They cannot simply choose to, for example, sing higher to avoid the noise we make in the ocean,' said Elemans. 

And while this may not be as big of a problem for humpbacks and other species that live in groups, blue whales which cover long distances solo may be more vulnerable to human shipping and other activities that produce undersea noise.