Whale Song
The songs of whales are sounds emitted by these whales to communicate. They talk about "songs" to describe repetitive and predictable printing of these messages, which depend on the species of whale that issues them.
The biological process that allows the animal to produce these sounds depends on the family to which he belongs. However, all whales, dolphins and killer whales use these sounds as sonar to detect underwater. In fact, light is hardly present at great depths, and this tool allows effective representation of their environment. According to some environmentalists , increased noise in the oceans, primarily because of human machines, interferes with these sounds and deceives the animal and often, this error is fatal.
Summary |
In humans, the sounds are produced as follows. Air pulmonary exhaled through the larynx where the vocal cords. Them in opening and closing segment of the air column in a series of puffs which are then shaped by the throat , the tongue and lips to form the desired sounds.
In cetaceans, the production of sounds derived from other processes. The mechanism is also different in odontocetes (toothed whales, including dolphins) from among the baleen whales (baleen whales, including larger whales such as the blue whale ).
Making Sound in cetaceans Odontoceti
Toothed whales do not produce low frequency sound known as the whale songs. Instead, they produce clusters of fast clicks and whistles of high frequency. Isolated clicks are usually used for echolocation , so that the series of clicks and whistles used to communicate. Although dolphins produce when in groups a real cacophony of various sounds, the meaning of these sounds remains mysterious. Frankel (1998) quotes a researcher who compared the noise produced by a group of dolphins that made by children in a playground.
The various sounds are produced by the passage of air through an anatomical structure located in the head, called phonic lips (phonic lips of English speakers) or snout monkey, similar to the nasal passages and humanities. When the air duct follows this narrow, it causes, like the hum human aspiration and the joining of the lips voice and the vibration of the surrounding tissues, emitting a sound. Vibration may, like the man does with his larynx for voice, be voluntarily controlled by the animal with great precision. For echolocation, the vibration passes through the brain tissue until the melon , a sort of sounding board who directs the beam shape and sound. All toothed whales except the sperm whale has two pairs of phonic lips and can make two sounds independently. The air that has passed between the phonic lips in the buccal sac. From there, he can be expelled outside through the vent or be returned to the lower part of the nasal device and recycled to make a new sound.
Recent analysis using the techniques of cranial CT axial tomography and single photon emission showed, at least in the case of the bottlenose dolphin , that the air could be routed to the aircraft nose from the lungs through the sphincter palatopharyngeal , enabling the process of sound creation to continue as long as the animal was able to hold his breath (Houser et al., 2004).
Making Sound in cetaceans baleen
Whales do not like structure muzzle monkey (phonic lips). Their larynx appears to play a role in sound production, but they have no vocal cords and the exact mechanism remains unclear. The process, however, is not completely analogous to that of humans because whales produce sounds without expiring. It is likely that they use air in a closed circuit. The cranial sinuses can also be used to create sounds, but researchers have not yet clearly explained the process.
The purpose of sound production in cetaceans
Unlike the complex and haunting songs of humpback whales (and some blue whales), whose aim is initially assumed the selection of sexual partners (see below), sounds simpler other cetaceans have a constant value. Although the toothed whales (including the killer ) are able to use the echolocation (directional transmission of ultrasound) to detect very precisely the size and nature of objects, baleen whales do not have this ability. Moreover, unlike some fish, like sharks , smell whales is not well developed. Sounds audible to humans play a role in navigation in their environment where visibility is low and the sound travels well. For example, the depth at which the major obstacles can be detected by the loud sounds made by whales to panonstus.
Song of the Humpback Whale
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spectrogram, 10 accelerated
Two groups of whales, humpbacks and blue whales in the Indian Ocean, are known to emit repetitive sounds at different frequencies, the so-called "singing whales". Philip Clapham (1996), Biologist U.S. Marine, described the sound as "the most complex of the animal kingdom."
The male humpback whales are not carried in this song that during the mating season, and it is possible that these sounds have an impact on sexual selection of partners. However, we do not have so much information, despite work on the subject, and the study of this hypothesis is subject to many current research.
Researchers Roger Payne and Scott McVay were the first analyzed these songs in 1971. The sounds follow a very distinct hierarchy. The base unit (sometimes called notes) is a continuous variable frequency between 20 Hz and 10 kHz, which lasts a few seconds. The human being is able to perceive sounds in the range 20 Hz - 20 kHz, so they we are perfectly audible without equipment. The frequency variation over a note can be a frequency modulation: towards acute to the grave, without change in power, or amplitude modulation: stronger, weaker or the same volume. This makes a total of 9 units of sound.
A sequence of 4 to 6 units form a sub-sentence, and lasts about 10 seconds. At least two sub-phrases form a sentence. A whale is usually repeated the same sentence for 2 to 4 minutes, what is called a theme. A series of themes form a song. Whales can repeat this song - which lasts about 20 minutes - for hours or even days. This linguistic hierarchy in "Russian Dolls" has captured the attention of researchers.
In addition, over time, the song of a whale is changing. For example, a note that originally increased its frequency ("upsweep") shall, as and when singing a constant note, another note can become stronger (louder). In addition to these few changes, others settle with age of the animal, in the months or years. The whales live in the same part of the globe have similar songs - apart, even the notes are completely different. But the logic remains the same.
A study of 19 years showed that the whale does not "return back": a song that has evolved continues to evolve, old songs are never pronounced thereafter.
Humpback whales also emit sound isolation, not belonging to a song.
A third category of song is the call to the meal ("feeding call). It is a song relatively long (5-10 seconds) at a frequency and a constant amplitude. Humpback whales usually feed them all together, by gathering to attack schools of fish. The exact reason for the issuance of this song is still unknown, but it is possible that fish recognize. Indeed, when we go back to using equipment adapted to the call of a whale meal, fish flee at the other end of the basin, although there is no whale.
Other songs of whales
Other whales emit sounds between 15 and 20 hertz. However, marine biologists at the Woods Hole Oceanographic Institution have reported in New Scientist in December 2004 that they had taken a whale in the Pacific Northwest for 12 years who had sung "at 52 Hz Scientists are currently unable to explain this important difference compared to the songs previously observed. However, they argue that the animal originally sound was indeed a whale, a species known, then suggesting that we probably underestimate the vocal ability of these animals.
Most whales and dolphins emit sounds of varying complexity. The beluga (or "sea canary") is especially for his songs punctuated by whistles, clicks and pulses varied.
Human Interaction
Although some people think that is too much interest in whales under the pretext that they are marine animals, most scientists agree that these songs have a leading role in the lives of these whales in their relations social development and in their diet. Some critics consider it a humane animal behavior than seeing meaning in these songs, for example equating the bellowing cattle.
Researchers use hydrophones (often used in the original military use to track submarines) to ascertain the exact position of the origin of sounds, to detect them even at great distances. Research by Dr. Christopher Clark of Cornell University gathering military data accumulated during 30 years show that the whale songs moves over 3000 km. In addition to the information thus derived on sound production in cetaceans, these observations allowed a better approach to the migratory route of whales during mating season - which also happens to be the season of singing.
Clark contends that, before the man from disturbing the surface of oceans, whale songs could probably cross the ocean from coast to coast. His research highlight the fact that the noise underwater ambient produced by humans (boats, submarines ...) double every decade. This greatly affects the sharpness and the transmission of sounds emitted by whales - some even suggest the hypothesis that this phenomenon disorient whales, which would then wash up on beaches. Other research, conducted in Canada , showed that near a major seaport, for example off the city of Vancouver , the killer whale adapt their frequency, increase the amplitude of their songs so that 'they are better audible. Noise pollution, limiting the communication between these animals, makes finding a partner difficult.
See also
Listening to whales
| Song of a humpback whale |
| Song of a killer |
| Orca song, at a distance |
| Killer whale vocalizations |
 | Difficulties in using these media? |
References
- (In) Lone Whale's Song Remains A Mystery, New Scientist, No. 2477, December 11, 2004
- (In) Sound production, Adam S. Frankel, Encyclopedia of Marine Mammals (pp. 1126-1137) ISBN 0125513402 (1998)
- (In) In search of impulse sound sources in odontocetes Ted Cranford in Hearing by Whales and Dolphins (W. Lu, A. Popper and R. Fays eds.). Springer-Verlag (2000).
- (In) gradually change in the songs of Humpback Whales (Megaptera novaeangliae): a Detailed Analysis of Two Seasons in Hawaii by KBPayne, P. Tyack and RS Payne in Communication and Behavior of whales. Westview Press (1983)
- (In) BBC News, 28 February 2005. Unweaving the song of whales
- (In) Humpback Whales by Phil Clapham ISBN 0948661879
- (In) Structural and functional imaging of bottlenose dolphin (Tursiops truncatus) cranial anatomy, by Dorian S. Houser, James Finneran, Don Carder, William Van Bonn, Cynthia Smith, Carl Hoh, Robert Mattrey and Sam Ridgway, Journal of Experimental Biology Volume = 207
External Links
- (En) Research on communication between whales at Cornell University
- (In) Listen live whale songs from the depths of the oceans
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