Fascinating Phenomenon of Whale Songs
Do whales really sing? Let's find out.
“In nature, nothing is perfect. Yet, everything is perfect,” Alice Walker once said. While animals do not have the benefit of language as a tool of communication, nature has given them their own means of communication. For animals of the Order Cetacea, which includes whales, it is the process of vocalisation that enables them to communicate with each other.
The first recordings date back to the 1950s, when U.S. Navy developed the ‘hydrophones’ for submarine warfare. The hydrophones ended up catching frequencies emitted by humpback whales as well. By 1971, researchers Roger Payne and Scott McVay were not only able to perform spectrographic analyses of these frequencies, but were also able to link these frequencies to the various visible behaviours displayed by humpback whales.
Vocalisation in itself is a very unique process. Whales use a variety of sounds for communication, and these sounds vary from one type of whales to another. Sound, in these cases, is also more effective because of the rather limited effectiveness of other senses in water. Due to the tighter molecular composition of water as compared to air, sound travels four times faster in water than in air. The sounds that whales produce are reminiscent of human singing. Hence, these whale vocalisations are also interchangeably called whale songs.
Different types of whales produce different sounds. Generally, the difference lies between Odontocenti (toothed whales) and Mysticeti (baleen whales). In Odontocenti, the sounds are usually characterised as rapid, high frequency clicks. The frequencies of these clicks range from 0.2 Hz to 150 Hz. While lower frequencies act as biological sonar and help the whales in finding directions and locations, higher frequencies reveal detailed information about the nearby surroundings. In fact, the frequencies and their understanding is so precise that whales can determine the size, shape, and speed of a target merely by using high frequency sounds. Furthermore, whales can also differentiate between the material compositions of various objects using these frequencies.
Mysticete whales on the other hand use a larynx to produce sounds. Herein, the vocal folds, which are structures akin to the vocal cords in terrestrial mammals, are known to be the cause of sound production.
Interestingly, whales do not produce merely primitive sound patterns. They have a rather complex system of communication consisting of different elements. The shortest sound produced by a whale is known as a ‘unit’, which can comprise of a moan, shriek, or wail. Collectively, six to eight units are called a phrase. These phrases are repeated for longer durations of time and therefore end up forming the ‘theme’ of the song, which usually lasts for 30 minutes. Furthermore, these songs are repeated over sessions, the average duration of which is 20 hours. These songs are in the form of a pattern, and are predictable in nature.
However, that again is not the full repertoire of whale vocalisations. It also includes the element of ‘cultural transmission’, wherein different elements of songs are learnt by separate whale populations, which further acquire the sounds or the themes and incorporate them into their own songs.
There is often the question of whether these sounds are a part of a deliberate communication process or just physiology. Researchers have argued that ingressive and egressive air movements can cause the sounds. Furthermore, the change in frequency caused by the shift in carbon dioxide/oxygen ratio, which occurs during a dive, can alter the resonant frequency of the vocalization.
Whatever the case may be, whale songs are a marvel of nature. They are simply melodious to listen to, and proof that the gift of music does not lie with human beings alone.
Editorial Support: Phoenix Content India
