DeepSummary
Researchers have discovered how baleen whales like humpbacks and blue whales produce their deep, haunting vocalizations despite evolving from land mammals. Unlike toothed whales which evolved a novel sound-producing organ in their nose, baleen whales use a modified version of their larynx - specifically a cushion and U-shaped cartilage structure that vibrates as air passes over it.
This laryngeal adaptation allows baleen whales to create very low frequency sounds from around 10-300 Hz by expelling air from their lungs. However, humpbacks and some others can also make higher frequency sounds by moving their vocal folds together like humans. The limited air supply when diving restricts baleen whales to vocalizing at depths shallower than 100 meters.
Crucially, the frequency range and depth at which baleen whales vocalize overlaps significantly with anthropogenic noise from shipping and boats. Since this noise is relatively new from an evolutionary perspective, the whales are unable to rapidly adapt their vocal anatomy to communicate outside of the noise-polluted range, potentially impacting their ability to find mates and food.
Key Episodes Takeaways
- Baleen whales like humpbacks produce their iconic low-frequency vocalizations using an evolved laryngeal adaptation involving a cushion and U-shaped cartilage.
- This vocal mechanism restricts baleen whales to communicating at low frequencies around 10-300 Hz and depths shallower than 100m.
- The low frequency range and shallow depths they vocalize in directly overlap with anthropogenic ocean noise from shipping and boats.
- Since this noise pollution is relatively new, whales cannot rapidly evolve new anatomical structures to vocalize outside the noise-polluted range.
- The research provides evidence for revisiting regulations around ocean noise to better protect baleen whale communication abilities.
- Humpbacks and some other baleen whales can make higher frequency sounds by actively moving their vocal folds together like humans.
- Unlike toothed whales which evolved a novel sound-producing nasal organ, baleen whales vocalize using a modified version of their ancestral larynx.
- The study's evidence came from analyzing larynx samples from beached whales that maintained good tissue quality before decomposition.
Top Episodes Quotes
- “So if you're on the ocean with a quiet sailboat, you would always hear the whale sing.“ by Kun elements
- “So combining our experiments and the models we made, we could now not only show what the actual mechanism is that these animals use to make sound, but we could also show what's the limitations of this mechanism.“ by Kun elements
- “So that means that the noise we make actually limits the communication range of these animals severely, and they cannot escape it, they cannot go deeper, and most animals can also not go into higher frequencies to escape the boat noise and the shipping noise and other types of noise we make for communication.“ by Kun elements
- “And since boat engines are such a new thing on evolutionary scales, the whales are not able to just evolve new structures within a few decades to escape this noise, basically, it's not something they can do behaviorally or by changing the motor control from their brain. They're really stuck by the physiology of the sound production in this frequency range, in this depth range, so they cannot escape human noise.“ by Kun elements
- “So I hope that this evidence we now have actually gives a good basis to look again at these laws and maybe see which frequency ranges and sound amplitude ranges are most restrictive for the whales and change our laws according to.“ by Kun elements
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Episode Information
Nature Podcast
podcast@nature.com
2/23/24
The deep haunting tones of the world's largest animals, baleen whales, are iconic - but how the songs are produced has long been a mystery. Whales evolved from land dwelling mammals which vocalize by passing air through a structure called the larynx - a structure which also helps keep food from entering the respiratory system. However toothed whales like dolphins do not use their larynx to make sound, instead they have evolved a specialized organ in their nose. Now a team of researchers have discovered the structure used by baleen whales - a modified version of the larynx. Whales like Humpbacks and Blue whales are able to create powerful vocalizations but their anatomy also limits the frequency of the sounds they can make and depth at which they can sing. This leaves them unable to escape anthropogenic noise pollution which occur in the same range.
Article: Evolutionary novelties underlie sound production in baleen whales
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