Scientists have long known that whales, sperm whales and dolphins communicate with each other by means of sounds. This communication reminds whale singing that is heard under water for many kilometers. A new study by scientists from the Woods Hole Oceanographic Institution (WHOI) found that some elements of the songs whales go unnoticed in previous works on the analysis of the scale. And we missed were important to communicate the elements of marine mammals.
The results of their work, scientists published in the online edition of Biology Letters (November issue). The main object of the study, according to the head of research Aran Mooney, steel whales, humpbacks. With a small boat he and his colleagues conducted the measurement of two components of the songs whales: conventional acoustic pressure waves (vibration of matter, through which the sound) and particle motion (physical vibration of substances while driving through sound). Scientists were surprised at how much new information has brought the study of these two types of sound waves.
"We have omitted the one side of the boat our equipment, and swam to the opposite side of the whales, which we studied. We did not expect that the motion of the particles caused by the sounds of whales, will be recorded as far away from the herd. In fact, this phenomenon was recorded at distances much larger than we expected, "- said Mooney.
Measurements of scientists conducted at a maximum distance of 200 meters from the whales. But they believe that this movement of the particles, particularly at low frequency sound can propagate much further. "This is a completely different manifestation of the use of sound than what we consider typical of whales", - the head of research.
To understand the difference between the described types of sound, you can imagine yourself sitting in a car, in which the music is played loudly. What we hear - a pressure wave, and something from which vibrates the seat - it is the movement of particles. "When it comes to whale songs, particle movement is not being investigated. It is more difficult to measure the wavelength than conventional speakers "- says Mooney.
The acoustic pressure wave can be easily detected by "hydrophone" - specialized underwater microphone. This device is sold everywhere. But the sound is distributed using the motion of the particles measured not so simple. To do this, you must use specific equipment - sensitive underwater accelerometers. Until recently they were almost inaccessible to researchers. Fortunately, Mooney and his team both types of sensors became available, scientists decided to use all that you can.
Experts say it is still not known whether whales capture the motion of particles, but the structure of the hearing in these animals suggests kosveenno confirms the assumption. Most likely, the low-frequency vibration is the basis of communication of whales. The analogue also have animals that are not fully aquatic lifestyle. It is a hippo who hear ordinary sounds, but apart from this, are able to perceive the vibration of the entire body of water. This hippos can detect specimen of its kind, located many kilometers.
In that are of great importance for the low frequency sounds of whales, scientist doubts. He fears that human activity causes the whales simply can not communicate normally. "Most of the sounds produced by a person in the sea - it is low-frequency sounds. The level of sound pollution is constantly increasing: increasing the number of ships, more than seismic surveys of the seabed and ocean floor, "- says Mooney. All this contributes to a low-frequency vibrations that literally prevent to live large marine mammals.
Today, by the way, that the whales could be the source of the strange sounds captured by the Canadian military agency in the area of the Strait Fury and Hecla Strait (Canada). Military attracted residents' complaints for unusual sounds on the northern coast of the country. Throughout the summer the Inuit settlement of Igloolik heard strange humming and squeaking. Private yachts, which appeared in the same region, a confirmation message Eskimos.
After the military conducted an acoustic scanning, we found out that in this place there were six walruses and whales two flocks. Perhaps whales and become a cause of concern military.
also recently reported that Shane Gero, a marine biologist from Aarusskogo University (Denmark) and colleagues found in the methods of communication culture of sperm whales. Scientists have found that different groups of sperm whales have their own traditions and even "language dialects". Sperm whales, which swim from one place to another, retain all the features of the communication over the years. In their study, Gero along with co-authors develop the idea of the possibility of the existence of a culture of sperm whales, or even "civilization".