Baleen whales evolved a unique larynx to communicate but cannot escape human noise

Baleen whales are the largest animals to roam our planet and top predators play an important role in marine ecosystems. To communicate and find each other over vast distances, baleen whales depend on the production of sounds that travel long distances in deep and dark oceans.

However, since Whale songs First discovered more than 50 years ago, it is not known how The baleen wheel Create their complex sound yet.

A new research in The nature Reports that baleen whales developed unique structures in their larynx that enable their low-frequency vocalizations, but also limit their range of communication.

The study was led by Vice Scientist Professor Koen Allemans, Department of Biology, University of Southern Denmark, and Professor Tecumseh Fitch, Department of Behavioral and Cognitive Biology, University of Vienna in Austria.

“The toothed and baleen whales evolved from land mammals with a larynx that served two functions: protecting the airways and producing sound,” says Tecumseh Fitch. and made strict demands to prevent suffocation underwater,” says Tecumseh Fitch.

The study shows that baleen whales can still make sounds with their larynx, but they have developed new structures to do so, which are only present in baleen whales. First, the tiny cartilages in the human larynx—called arytenoids—that change the position of our vocal folds have changed dramatically in whales.

“The arytenoids evolved into large, elongated cylinders that joined at the base to form a large U-shaped rigid structure that extended almost the entire length of the larynx,” says Allemans.

“This is likely to maintain a tight open airway when they have to move large amounts of air in and out while breathing at explosive levels,” Fitch says.

“We found that this U-shaped structure pushes against a large fat cushion inside the larynx. When the whale pushes air from its lungs past this cushion, it begins to vibrate and this causes the water to flow. Very low-frequency sounds are generated inside,” says Allemans. .

Trying to work on biology and especially the physiology of whales is very difficult.

“Even though humans hunted whales to the brink of extinction, they tried to learn about their physiology,” says Magnus Wahlberg, a whale expert at the University of Southern Denmark and co-author of the study. I tried very little.”

“Strandings are unique and rare opportunities to learn about these amazing animals, but even then, it’s very difficult to study physiology, because the tissue degrades so quickly. Whales are notorious for beaching themselves. ,” adds Wahlberg.

Thanks to the Danish and Scottish marine mammal stranding networks, researchers can quickly extract the larynx of sea, minke and humpback whales for close-up investigation in the lab.

“Our experiments showed for the first time how whales make their very low-frequency sounds,” says Allemans.

To understand how Muscle activity can change calls, the researchers created a computational model of an entire whale’s larynx.

“Our model includes accurate 3D shapes. larynx and its muscles, which made it possible to mimic, for example, how frequency is controlled by muscle modulation,” said Professor Qian Zhou of the Department of Mechanical Engineering at the Rochester Institute of Technology in the US and Zudong Zheng says.Study

“Our model accurately predicted the results of our experiments, but we could also calculate acoustic properties that we couldn’t measure in the lab, such as the frequency range,” post Rochester Institute of Technology, USK. Dak, says Weili Jiang. the study.

The models predicted the natural sound of the whale very well.

However, these new discoveries Physical characteristics What allowed the whales to successfully navigate vast oceans, there are also insurmountable physical limitations for many baleen whales.

Combining experiments and models, researchers provide the first evidence that baleen whales are physically unable to avoid human noise, as it masks their vocalizations, thereby limiting their range of communication. Is.

“Unfortunately, the frequency range and maximum communication depth of 100 meters we predicted overlap completely with Ghalib. Cover vibration and depth of man-made noise caused by shipping traffic,” says Allemans.

“The first sound recording of Humpback whale “Roger and Katie Payne’s song in 1970 resonated deeply with humanity, launched the burgeoning field of marine biology, and sparked global interest in marine conservation efforts,” says Kevin Allemans.

“These recordings were so politically important at the time that they were aboard the Voyager space mission,” he continues.

Payne made people aware of how calm the seas were before humans began to widely use propeller ships and continuously run shipboard generators. They were marine whales that evolved.

Allemans adds, “Compared to the seventies, our oceans are now even more saturated with man-made noise from shipping lanes, drilling activity and seismic guns. We need stricter regulations for such noise, because it “Whales depend on sound to communicate. We show that despite their amazing physiology, they are literally immune to human noise in the oceans.”