Nature
Ever wondered what noise a shark makes? If you have no idea, you’re not alone. For a long time we thought these animals were pretty much silent and didn’t make active sounds, but now new research has captured the first ever recordings of sharks making noises. And what do you know? They click.
The discovery was something of a happy accident as the team only picked up on the noises while doing behavioral hearing tests on sharks. The investigation centred around New Zealand rig sharks (Mustelus lenticulatus) that had to be handled underwater as part of the investigation. When the researchers played back recordings, they were frankly stunned to hear what sounded like little shark protests.
I am very curious if and when these sharks click in the wild
Carolin Nieder
“I was very surprised as I was under the assumption that sharks don't make sounds,” said lead author and postdoctoral investigator at the Woods Hole Oceanographic Institution (WHOI) Carolin Nieder to IFLScience. “At first, we thought it might be a strange artifact. However, with time as the animals got used to the daily experimental protocol, they then stopped making the clicks all together, as if they got used to being in captivity and the experimental routine.”
“This led us to consider that maybe we are observing a sound-making behavior rather than a strange artifact. About one year later a paper published by Fetterplace et al (2022) documented clicks produced by wild sting rays in response to approaching divers. It was then when we thought it might be worth documenting our observation.”
This marks the first documented case of active sound production in a shark. As for how they make it, rig sharks have plated teeth that if snapped together forcefully could theoretically make this kind of clicking sound. However, the team emphasizes we don’t yet know this is the source of the sound for certain, and it’s something Nieder hopes to one day experimentally test.
So, still some questions to answer, but the discovery is already shaking up what we know about these “silent” animals.
“I think it could change the way we think about how sharks use sounds in the ocean,” continued Nieder. “Perhaps sounds and sound production are more important to these ancient fish than we currently understand. I think there is a chance that other sharks are making similar noises, maybe sharks that have similarly flattened teeth, which we think could be involved in the production of these clicks – through forcefully snapping the flattened teeth – but this also needs further testing. We can only speculate at this point.”
"I would like to properly (experimentally) test our teeth-snapping hypothesis and, of course, I am very curious if and when these sharks click in the wild."
Nieder hopes that the team’s documentation might inspire others to start “listening” to sharks, as it could be that now we know what to keep an ear out for (and have more advanced equipment), we might start really hearing them. Unlocking how sharks use sound could reveal new insights into their ecology, behavior, and ecological niches, as well as being an important tool for conservation strategies in an ocean environment that’s getting ever noisier.
The study is published in Royal Society Open Science.
