The primordial deep, it turns out, is a very chatty place.
In a new study published in the journal Ichthyology & Herpetology, Cornell University researchers reveal that fish rely on acoustic communication far more than previously thought.
People have long known that fish make sounds; in his History of Animals, Aristotle describes the “noises and squeaks” fish produce, sometimes by grinding their own bones against each other in a mechanism called stridulation. Yet for decades, a lack of adequate underwater microphones and recording technology has kept scientists in the dark about just how many species of fish make noises, and whether those noises are the incidental rumblings of speechless creatures, or actually constitute communication.
Now, researchers have learned that sounds are “a major mode of communication among fish, rather than just limited to a few oddballs”, says lead author Aaron Rice, a researcher at the K Lisa Yang Center for Conservation Bioacoustics at the Cornell Lab of Ornithology. Not only is acoustic communication widespread among fish, but Rice and his team’s analysis of sound-producing physical characteristics (like certain swim bladder musculature) across species suggests that ancient sturgeons first started chatting aloud 155m years ago, right around the same time some tetrapods, like birds and mammals, began speaking up, too.
Moreover, the study found that acoustic communication among different fish species has independently evolved at least 33 different times, probably due to the diversity of their habitats. This pattern suggests to researchers that more soniferous fish species and families exist and are yet to be recorded, and highlights the important role that acoustic communication has played in the history of vertebrates.
What are fish talking about? Mainly sex and food, it seems. “We see more elaborate sounds being produced in reproductive contexts,” says Rice. How these noises actually sound to humans varies widely; scientists use a variety of onomatopoeic descriptors like “boops”, “honks” and “hoots” to convey what they’re hearing. Some fish, like the three-spined toadfish, sound similar to croaking frogs, whereas others, like the midshipman fish, emit low, haunting, foghorn-like hums. Prior research on the noises produced by highly vocal codfish even found fish can have regional accents strong enough that others in their species may find them hard to understand.
Recognizing the extent to which fish communicate using sound allows researchers to better determine the effects of noise pollution on many different aquatic species. Researchers consider noise pollution to be as harmful as overfishing, water pollution and the climate crisis, negatively affecting marine mammals and at least 21 species of fish that rely on their hearing to thrive. Cornell’s study suggests the threat posed by noise pollution is even more severe. “If you have literally millions of individual fish that are relying on communication sounds for the success of their populations, perturbing their acoustic environment may have real consequences,” says Rice.
Rice hopes that capturing and cataloging fish sounds online will allow the public an opportunity to better connect with the often inscrutable creatures. Hopping on to a computer and listening to the sounds of the ocean could be a way to get people interested in and concerned for the wellbeing of fish the way we are with more familiar and charismatic animals, like birds.
Andrew Bass, a behavioral and evolutionary neuroscientist and co-author of the study, hopes the research will help humans better appreciate the complexity of other animal societies overall.
“There’s a reason why all these other species exist and have been successful,” he says. “A big piece of that success is social communication … [Humans] have very sophisticated language, but I think what our study shows is that the whole history of social communication using sound is very old. And that means we can learn a lot from other animals about ourselves.”
