Why do whales sing? - Stephanie Sardelis
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Want to learn more and hear more dolphin and whale sounds? Explore Voices in the Sea.
Of the over 80 known species of whales and dolphins, cumulatively known as cetaceans, only some species of baleen whales produce songs. These songs have specific structures to them: units are compiled into phrases, which are ordered into themes, and repeated to form complex songs. Listen to some of them at this link.
As far as we know, only males sing. The ultimate purpose of whale song remains a mystery, although scientists have suggested some likely explanations: whale songs might be used to attract females while at breeding grounds, or to deter other males from breeding or feeding sites. Whale songs might also be used for orientation during migration, or as a display of social status to other whales. Regardless, whale songs are certainly an important aspect of the lives of marine mammals, as vocalizations are the most efficient signals transmitted in the dark, murky ocean.
Another mystery surrounding whale songs is how they physically produce sounds. Unlike humans, the trachea and nasal passage of whales are completely separate, and whales do not have vocal cords. The biggest factors inhibiting our understanding of how these animals produce songs are that we cannot keep them in captivity due to their massive size and we cannot monitor their internal organs while they are still alive. But, anatomists that work with dead, beached whales have shed some light onto the subject by identifying the U-Fold: a flap of skin over which air passes to create vibrations, similar to how our vocal cords work. While it is nearly impossible to confirm that this is the function of the U-Fold, it is a highly likely theory and the best developed to date. Read more about it here. Here is a visualization of where the U-Fold is positioned and how vibrations from it are amplified through the laryngeal sacs to produce loud, ocean-spanning songs.
Scientists have developed technologies to listen to whale songs underwater in order to investigate their purpose and track the whales for conservation. Hydrophones, or specialized underwater microphones, are used to record marine mammal sounds all over the world. These sounds are then turned into images, called spectrograms, which visualize vocalization patterns. Here are some great examples of the different sounds marine mammals make (songs or otherwise), and what they look like as spectrograms. Each marine mammal makes distinct sounds, which appear as unique spectrogram markings, making species identification from sound files easy and effective.
Once scientists have recorded marine mammal vocalizations, they can use the timing and location of the sounds to understand where marine mammals are going and when. By developing a thorough understanding of the migration routes and key habitats used by marine mammals (particularly those that are endangered), we can protect them with greater accuracy. Marine Protected Areas with restrictions on shipping speed and density can be developed based on acoustics to limit dangerous encounters of whales with ships (including lethal vessel strikes/collisions and masking of communication from shipping noise). For example, here is a case study of how acoustic tracking was used to study endangered North Atlantic right whales.
Using whale songs as a conservation tool is particularly effective because people love to connect with animals that communicate with complexity equal to that of humans. Many organizations provide followers with live transmissions of whale songs in order to inspire audiences and encourage the protection of our oceans. For instance, livewhales.com is a program that distributes humpback whale songs recorded live off of the Hawaiian coast from January through March. Whale songs spark our imagination and bring together a global community of conservation-minded individuals dedicated to protecting the oceans and their musically inclined inhabitants.
Special thanks to Reidenberg, Joy S., and Jeffrey T. Laitman. "Discovery of a low frequency sound source in Mysticeti (baleen whales): anatomical establishment of a vocal fold homolog." The Anatomical Record 290.6 (2007): 745-759.
Looking for more lessons on whales? Try these from TED-Ed:
How whales breathe, communicate ... and fart with their faces by Joy Reidenberg
Why are blue whales so enormous? by Asha de Vos
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