Whales verbal communication
Whenever psychologists try to define the most distinctive feature of human nature, a complex and articulated system of verbal communication is mentioned in the first place. By comparing any human language with any vocal language of any land animal, the enormous difference in complexity appears evident. However, when we bring cetaceans into the picture, the term “distinctive” referred to humans results rather inappropriate.
How whales produce sound
All cetaceans in fact use an extremely complex set of sounds to communicate with each other, as well as to sense the surrounding environment. Before understanding how they do that, we need to make an important distinction: the infraorder “Cetacea” is divided into two superfamilies: Odontoceti (toothed whales) and Mysticeti (baleen whales). Although they share certain similar features, having a recent common ancestor, there are also significant differences between the two groups. Among them, the way they produce sounds, and the reasons why they do that.
Orca
Toothed whales (including dolphins, orcas, belugas, pilot whales, melon headed whales, sperm whales, etc.) have a special structure within their nasal cavity, right before their blow holes, which is very similar to humans’ vocal cords, called phonic lips. By contracting such structures while blowing small amounts of air through it, they can produce a broad variety of sounds, which ranges from clicks and squeaks up to whistles, on a broad range of frequencies (far broader than the frequency range of human voice).
Clicks are mostly used for echolocation, in a similar way of the sonar system of ships and submarines: the emitted sound hits the objects/animals located ahead of the whale, and it is reflected back to it, amplified by a system of bones and fatty matter located in the whale’s skull, and finally detected by the whale’s inner ears. In this way the whale succeeds in determining the size of the object/animal, its distance and even the direction and speed of its movement. This turns out extremely useful when hunting fishes or squids, as visibility underwater is far lower than on land.
Whistles are instead used for communicating with other individuals. One evident form of whale communication is that regarding each individual’s identity, characterised by specific “signature whistles”. These are used to signal each individual’s presence and position to the other nearby individuals. What is mind-blowing is that individuals of certain species of toothed whales have been observed calling each other by reproducing the whistle signature of the other individuals. This behaviour is actually a specific application of a whale’s ability to imitate and reproduce the pattern of sounds that they hear, no matter how complex they are.
Other kinds of whistles are used to interact with other individuals for a variety of purposes, such as communicating one’s intentions based on the emotional state of the moment (hungry: let’s go hunting; playful: let’s play; aroused: let’s have sex).
Differently from toothed whales, baleen whales (including blue whales, fin whales, humpback whales etc.) do not have phonic lips, but a larynx that lacks vocal folds. The sound therefore is produced in a very different way from how humans and toothed whales make it. The exact mechanism is not completely understood, but the sound is probably produced by squeezing and re-circulating air through the larynx cavity, as no air moves out from the mouth or nose during the vocalizations.
Whale communication by song
Another important difference with toothed whales is that baleen whales use sounds mainly for interacting with other individuals of the same species, as echolocation is not required for feeding purposes (although it might still be useful for navigation purposes). The most notable form of vocal whale communication used by certain species of baleen whales, in particular humpback whales and certain blue whales, are the so-called “whale songs”. These are the most complex systems of vocal whale communication known in the whole animal kingdom, after human language.
Pygmy blue whale
Their structure in fact consists of complex, “Matryoshka dolls” like patterns of sounds, composed by different levels of melodic lines. At the base there is a unit, which consists of single emissions of sounds lasting a few seconds, and which can be modulated both in frequency and in amplitude. A group of 4-6 units constitutes a bub-phrase, a 2 sub-phrases constitute a phrase, which usually lasts for about 20 seconds. Phrases can be repeated over and over for a handful of minutes, making a theme, before the whale starts singing a new theme.
A whale typically sings several different themes throughout a timeframe of around 30 minutes, making a song. The same song can be sung over and over by the same whale for several hours, and sometimes for whole days. What is interesting is that all the whales belonging to the same species and living in the same geographical area sing exactly the same songs, and these songs are slightly changing throughout the time. The main purpose of these songs seems to be finding a partner for reproductive purposes, as they are sung predominantly during the mating season.
Songs however are not the only form of vocal whale communication between baleen whales, as stand-alone sounds are also used, for a variety of purposes. One of them is the feeding call, which is a 5-10 seconds long sound of nearly constant frequency that humpback whales emit just before launching together onto a bank of sardines. Although the exact function of this sounds is not known, I like to think that it just corresponds to our “enjoy your lunch”.
Whales in Timor Leste
Melon Headed Whales – Jose Cortez
At least a third of the world’s known cetaceans can be found in the coastal waters of Timor Leste with 24 species confirmed as residing or passing through Timor Leste’s waters. One of the biggest whales on the planet, the pygmy blue whale, growing up to 23m in length, migrates from their feeding grounds in Southern Australia to their calving grounds in the Banda sea in June-August then returns October-December.
The best time to see the Pygmy Blue whales is October and November, take a look at our whale watching trips
For more information take a look at the whales and dolphins of Timor Leste website, dedicated to the understanding and protection of cetaceans in Timor Leste.
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Header photo – Pygmy Blue Whale thanks to Guy Warnock
Giovanni d’Erasmo
PADI Dive instructor at Dive Timor Lorosae and M.Sc in Marine Sciences