by Whale songs are strange, interesting and sometimes disturbing, one of the most mysterious sounds to be heard reverberating through the ocean.
How baleen whales, including humpback whales, are able to sing underwater has puzzled scientists since whale songs were first discovered more than 50 years ago.
While toothed whales, including dolphins and killer whales, have developed a vocal organ in their nose to produce sound, baleen whales are thought to use a larynx – or voice box – in their throat to do so, according to a new study published in the journal Library. Nature magazine on Wednesday.
The larynx of baleen whales is shaped differently from other mammals. It has long, rigid, cylinder-like cartilages that form a U shape. This structural adaptation allows the leviathans to breathe in and out large amounts of air when they surface, according to the study.
In the respiratory tract, the nasal and oral plugs protect the airways from water when the marine mammal is breathing and eating.
Air sacs also evolved in a way that could allow baleen whales to recycle air while creating vocal sounds, according to researchers.
Unlocking the way whales vocalize could help scientists better understand the impact of man-made noise pollution in marine waters on the ocean giants.
In addition to documenting wildlife recordings, researchers were able to find a sei whale, a humpback whale and a minke whale soon after they died between 2018 and 2019 and study them in detail in the laboratory. “This level of analysis has never been done before,” lead study author Coen Elemans, a professor of bioacoustics at the University of Southern Denmark, told CNN on Thursday.
The scientists also created computer models of the whales’ voice boxes that simulated aspects they could not measure in the laboratory, such as the effect of muscle contraction on sound production.
Through this simulation, the researchers discovered that there is a “completely new mechanism that has not been described in any other animal,” Elemans said.
Among the specialized structures was a cushion of fat that vibrated when air was pushed out of the lungs, allowing the whales to create low-frequency sounds underwater to communicate over great distances.
Since the ocean is dark, sound is the main method that whales have to find each other and, therefore, a mate, Elemans said. The study solves a puzzle “for a whole group of iconic animals,” he said.
“They are like the largest animals that have ever roamed this planet. They are very intelligent, they are very vocal, they are very social. And for those animals, we now understood how they managed to communicate with each other on the water. And this probably evolved like 40 million years ago and allowed whales to thrive today,” he continued.
Human interference
However, this “cool” mechanism puts “limits” on the whales, Elemans said.
The baleen whales were only able to make low-frequency sounds from the surface of the water to a maximum depth of about 328 feet (100 meters), the study team found. That is because the whales cannot be too far from the surface of the ocean because they need air to produce their calls, which have a maximum sound frequency of 300 hertz.
This depth and frequency overlaps with noise made by most man-made vessels, which today are often between 30 and 300 hertz near the ocean surface, according to the study .
This means that most of the boating noises are calls between baleen whales, reducing the distance they can communicate.
“We have to change the noise we make, the type of noise we make, when we make it, where we make it. And we hope that this study can help to … reduce the noise we make,” said Elemans.
Evolutionary biologist James Rule, a research fellow at London’s National History Museum who was not involved in the research, described the study as “groundbreaking,” telling CNN on Thursday that it suggested “a new way whales produce complex songs about water.”
The finding that the whales are limited in the frequency of the sound they can make is “important, because human-made noise pollution in the ocean is an ever-growing problem that affects the lives of marine mammals,” he said. he.
“This shows the vital role that the study and digitization of animal morphology plays in answering some of the biggest questions about the lives of the most obscure and mysterious animals (on earth),” he added.
Ellen Coombs, a Peter Buck Postdoctoral Fellow at the Smithsonian National Museum of Natural History who was not involved in the study, said in a statement to CNN, “Many baleen whale populations are beginning to increase in numbers due to the cessation of most countries have commercial whales — but it seems these magnificent animals are now dealing with the next man-made challenge, and it’s a noisy one.”
The study, which “just started to scratch the surface,” involved young animals of only a few animal species, Elemans said, adding that his team would like to study adult animals next.
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