In the 1970s it was recognized that baleen whales are very vocal
It’s one of the most haunting sounds on Earth – the “song” of baleen whales such as humpback whales, which can be heard far across the water. Now, scientists have finally figured out how these filter-feeding marine mammals do this.
Baleen whales, including the blue whale, the largest animal in Earth’s history, use larynxes, or vocalizers, that are anatomically modified to produce sounds underwater, researchers said Wednesday. Researchers say they evolved a novel structure – a pad of fat and muscle inside the larynx.
This means that baleen whales use their larynxes to make sounds like humans do, while toothed whales – which include dolphins, porpoises, killer whales and sperm whales – have evolved a different mechanism, using specialized organs in their nasal cavities.
It was recognized in the 1970s that baleen whales are highly vocal, but exactly how they produce the range of sounds remains unclear.
“These are among the most spectacular animals our planet has ever seen. They were highly intelligent social animals that dwarfed most dinosaurs and fed on the smallest shrimps. They had the rare ability to learn new songs and spread their culture of sound to the south said Coen Elemans, a biologist at the University of Denmark and lead author of the study published in the journal Nature.
“To communicate and find each other in the dark ocean, baleen whales rely heavily on the production of sound. For example, female humpback whales and their calves communicate with each other through sound, while male humpback whales sing to attract Females,” Ellemans added.
All baleen whales, including fin whales, baleen whales, right whales, gray whales, minke whales, bowhead whales, etc., emit very low-frequency calls that are almost inaudible to humans. Some species, including humpback and bowhead whales, emit higher-pitched sounds that are more familiar to people as whale songs.
The researchers conducted laboratory experiments using the throats of dead sei whales, common minke whales and humpback whales that were stranded on beaches in Denmark and Scotland. They also developed a three-dimensional computer model of the whale’s larynx to simulate the effect of muscle contraction on sound.
In humans, speech involves the vocal cords in the larynx – the vocal cords. These small strips of vibrating tissue stretch across the airway, supported by small cartilage structures called arytenoids, that rotate to open or close the larynx.
In baleen whales, the arytenoids are large and stiff, forming a ring that presses against the throat pads. When the whale exhales, this pad vibrates in waves due to the airflow, creating sound.
“What’s fascinating is that although the changes in the larynx are unique and an entirely new structure, the physical principles of the interaction between air and tissue that are the primary source of sound follow the same principles as in other mammals. principles, including humans and birds, from bats to tigers to elephants,” said W. Tecumseh Fitch, an evolutionary biologist at the University of Vienna and study co-author.
“It appears that all of these biological species utilize the same set of tricks to produce sounds, although they use different organs or parts of organs to produce sounds,” Fitch added.
The larynx evolved when the first land vertebrates began breathing air and needed to separate food from the air to prevent suffocation. Whales evolved from land mammals about 50 million years ago. Modifications of the larynx allow baleen whales to vocalize underwater while protecting their airways.
“Returning to the ocean posed serious challenges for early whales, requiring adaptations to inhale and exhale large volumes of air during explosive surface breathing, avoid suffocation and drowning, and retain air during underwater vocalizations,” Ellemans said.
Research has also shown that the whales’ vocalizations occur in the same frequency range and ocean depth (about 330 feet (100 meters) deep) as human-made shipping noise, interfering with their ability to communicate.
“Unfortunately,” says Elemans, “baleen whales are physiologically constrained from singing higher or lower easily to avoid human noise.”
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