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Recent research challenges the long-held perception of sharks as silent predators of the sea. Evidence suggests that these creatures, often assumed to be non-vocal, may actually produce sounds purposefully, marking a significant discovery in marine biology.
According to a study published on March 26 in Royal Society Open Science, evolutionary biologist Carolin Nieder from Woods Hole Oceanographic Institution asserts that the clicking sounds produced by the flattened teeth of sharks could be the first documented instance of intentional sound production in these species. This finding emerged during Nieder’s work on auditory responses in a small shark species known as rig (Mustelus leucticulatus) at the University of Auckland’s Leigh Marine Lab in New Zealand.
The phenomenon was initially discovered incidentally. Nieder was lowering an underwater microphone into the tank when, while handling one of the rig sharks, she heard distinct clicking noises. Intrigued, she conducted further tests, finding that sharks could produce an average of nine clicks over a span of 20 seconds when grasped. This clicking is believed to originate from the clashing of their uniquely shaped, flattened teeth, which are adapted for crushing the shells of crustaceans.
Shark Sounds: A New Avenue of Research
Nieder’s work is pivotal, as it highlights an area of study that has been largely overlooked. Traditional research on fish communication has largely focused on bony fishes, where a range of sounds — from chirps to growls — have been documented in controlled environments. In contrast, the cartilaginous relatives of fishes, such as sharks and rays, have not been extensively studied for sound production.
The notion that sharks can generate noise raises intriguing questions regarding their communication methods. While handling the sharks, Nieder noted that movement did not appear to affect the sound production — clicks were recorded whether the sharks were wriggling or still. This observation led her to suggest that the sounds were made through a forceful snapping mechanism of their teeth.
However, further research is necessary to substantiate these claims. Currently, the study primarily focused on assessing the hearing capabilities of the sharks, revealing a frequency response limited to below 1,000 hertz. For context, human hearing can detect sounds up to 20,000 Hz. This discrepancy indicates that sharks may require louder sounds for communication compared to smaller fish, such as goldfish, which are more attuned to subtler auditory cues.
Nieder emphasizes that while sharks possess remarkable sensory capabilities, including an acute sensitivity to electric fields in their environment, their auditory range presents challenges for establishing direct communication. “If you were a shark, I would need to talk a lot louder to you than to a goldfish,” she explains, highlighting the need for more pronounced sounds to engage them successfully.
This research opens a new chapter in our understanding of shark behavior and communication, suggesting that these creatures may be more socially complex than previously assumed. As studies continue, scientists hope to unveil further details about the acoustic world of sharks, potentially redefining how we perceive their interactions within marine ecosystems.
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www.sciencenews.org