Previously unknown whale song components found.

Scientists have long known that whales, sperm whales and dolphins communicate with each other using sounds. At the same time, whale communication resembles singing, which can be heard underwater for many kilometers. A new study from Woods Hole Oceanographic Institution (WHOI) showed that some elements of whale songs went unnoticed in the course of previous work on the analysis of the scale. And missed were important for communication elements of marine mammals.

The results of their work, scientists have published in the online edition of Biology Letters (November issue). The main object of the study, according to research leader Aran Muni, was humpback whales. From a small boat, he and his colleagues measured the two components of whale songs: ordinary acoustic pressure waves (vibration of a substance through which sound passes) and particle movement (physical vibration of a substance as sound moves through it). Scientists were surprised at how much new information has come from studying these two types of sound waves.

“We lowered our equipment on one side of the boat, and sailed in the opposite direction from the whales we studied. We did not expect that the movement of particles caused by the sounds made by the whales would be fixed so far from the herd. In fact, this phenomenon was recorded at distances much greater than we expected, ” said Mooney.
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The measurements were carried out at a maximum distance of 200 meters from the whales. But they believe that this movement of particles, especially with low frequency sounds, can spread much further. “This is a completely different manifestation of the use of sound than what we thought was characteristic of whales,” the study leader said.

In order to understand the difference between the described types of sound, you can imagine yourself sitting in a car in which music is playing loudly. What we hear is pressure waves, and what the seat vibrates is the movement of particles. “When it comes to whale songs, the movement of the particles is not investigated. These are more difficult to measure waves than ordinary acoustic waves, ”says Mooney.

Acoustic pressure waves can be easily detected using a “hydrophone” - a specialized underwater microphone. This device is sold everywhere. But the sound propagated by the movement of particles is not so easy to measure. To do this, you need to use specific equipment - sensitive underwater accelerometers. Until recently, they were almost inaccessible to researchers. Fortunately, Mooney and his team have both types of sensors at their disposal, the scientists decided to use all that is possible.

Experts say that now they still do not know whether whales can detect the movement of particles, but the structure of the organs of hearing in such animals testifies to cosquinous confirmation of the assumption. Most likely, it is low-frequency vibration that is the basis of whale communication. The analogue is in animals that do not lead completely aquatic lifestyle. We are talking about hippos, which are heard and the usual sounds, but other than that, are able to perceive the vibration of the water all over. Due to this, hippos can find an individual of its own species, located many miles away.

The fact that the whales are of great importance for the sounds of low frequency, the scientist has no doubt. He fears that human activity leads to the fact that whales simply cannot communicate normally. “Most of the sounds made by man at sea are low-frequency sounds. The level of sound pollution is constantly growing: the number of ships is increasing, more seismic surveys of the seabed and the ocean floor, ”says Muni. All this contributes to an increase in low-frequency vibrations, which literally interfere with living a large marine mammal.



Today, by the way, it was the whales that could become a source of strange sounds recorded by the Canadian military in the Fury & Hekla Strait (Canada). The military was attracted by residents' complaints about unusual sounds off the northern shores of the country. Throughout the summer, the Eskimos from the settlement of Igloolik heard a strange buzz and squeak. Private yachts, which turned out in the same region, confirmed the reports of the Eskimos.

After the military conducted an acoustic scan, we managed to find out that there were six walruses and two whales in this place. Perhaps the whales were the cause of military concern.

It was also recently reported that Shane Gero, a marine biologist from the University of Aarhus, Denmark, and colleagues discovered culture in sperm whales communication methods. Scientists have found that different groups of sperm whales have their own traditions and even “language dialects.” Sperm whales, who float from one place to another, retain all the features of their communication over the years. In his study, Gero and his co-authors develop the idea of ​​the existence of culture or even “civilization” among sperm whales.