Whales and Sound
Having evolved for the past 38 million years suspended underwater, the way that whales engage with and use sound is unimaginably different from the way that we humans interact with our terrestrial surroundings. Surprisingly, cetaceans originally evolved from mesonychids – an extinct species of hoofed carnivore. Since their development under the sea however, the structures responsible for sound creation and perception in whales have changed significantly. In contrast to many terrestrial species that depend mostly on a combination of visual and auditory cues, cetaceans rely primarily on sound vibrations to navigate through the depths of the ocean.
Sound is such a vital component of a whale’s reality also due to how easily sound vibrations move through the water -- they travel 4X faster in water than vibrations produced in the air! Not only can signals be sent quickly to communicate with other whales or family members, but some sounds produced under water can be heard from miles away. This allows whales to move or make decisions as a collective, without needing to maintain eye contact with each other. The underwater speed of sound also helps whales detect elusive prey – sometimes with the help of echolocation, as in the case of toothed whales. Overall, sound is what ties whales to their reality. How they perceive shapes and movements. It fosters bonds between families, and it allows whales to communicate across the expanse of the ocean. Sound for whales, is our vision, our sense of smell. They use sound to investigate the shape of a rock where we would run or fingers along its edges. Sound is how whales engage with the world that surrounds them.
Although we cannot understand what is being perceived or shared between whales, we also cannot underestimate how important sound may be for their understanding of the ocean or of each other.
How Do Whales Produce Sound?
Toothed whales produce sound by passing air through what are called the phonic lips (kind of like human sinus passageways)—creating vibrations that are channelled through surrounding tissues to the melon, a chamber located in the whale’s forehead. From there, sound is directed outwards with both control and accuracy.
Although it is not known with great detail, baleen whales, produce sound more akin to humans and other terrestrial mammals. Humans create sound vibrations by pushing air over the vocal cords and adjusting pitch and tone using the larynx. It has been proposed that like humans, baleen whales also generate sound by passing air over their vocal folds. Unlike terrestrial mammals however, baleen whales are able to create sound without breathing. For as long as 15-20 minutes for example, humpbacks can sing without releasing any air from either their mouths or blowholes by recycling air through their vocal structures.