Sharks Break Their Silence: New Study Finds Rig Sharks Produce Sounds

For centuries, sharks were thought to be the silent predators of the ocean, gliding stealthily without making a sound. However, groundbreaking research from the University of Auckland’s Leigh Marine Laboratory has shattered this perception, revealing that sharks, specifically the rig shark (Mustelus lenticulatus), can actively produce sounds. The study, published in Royal Society Open Science, presents recordings of unique clicking sounds emitted by these small, bottom-dwelling sharks when handled underwater. The discovery challenges the longstanding belief rooted in shark biology – as sharks lack swim bladders, vocal cords, and other sound-producing structures, they were presumed silent. Yet, during hearing experiments, ten juvenile rig sharks emitted distinct clicks, possibly as a defensive response to the stress of being handled. This insight suggests sharks might use sound as a deterrent or warning, akin to the behavior seen in other fish species like cod and piranhas. The mechanism behind these clicks appears to involve the rig shark's blunt, interlocking teeth. Rapid jaw movements create a snapping action, likely generating the sharp clicks. These sounds are primarily broadband with a peak frequency far above the rig’s hearing range but still include low frequencies potentially audible to sharks. While the purpose of these clicks remains uncertain, they may serve as stress signals or even communicate with other marine creatures, including predators. Intriguingly, not all sharks exhibit this behavior. Tests on the dusky smoothhound, a close relative, triggered no clicks, possibly indicating varied sensitivity or adaptive differences among shark species. This discovery shifts the narrative of shark communication, suggesting a complexity previously unrecognized. While other sharks may yet reveal their own acoustic behaviors, the study underscores the rich potential for further exploration of marine life’s soundscapes. It’s a reminder that even in the ocean's quietest corners, much remains to be discovered about these fascinating creatures. The study's revelations, backed by advanced imaging and dissection techniques, invite deeper investigation into the acoustic abilities of sharks and rays, suggesting that these predators of the deep might have more to say than previously believed.