Biologists Document First-Ever Case of a Shark Intentionally Producing Sounds
A groundbreaking study has revealed the first known instance of a shark deliberately making sounds, challenging long-standing assumptions about shark communication. Published in Royal Society Open Science, an international team of marine biologists observed several sharks emitting clicking noises when handled, prompting researchers to explore the mechanisms behind this phenomenon.
Sharks and Sound Production: A Scientific Surprise
For years, scientists believed sharks were incapable of producing sounds due to their lack of swim bladders—the organ most fish use to generate noises. Additionally, anatomical studies have shown no specialized structures in sharks that could facilitate sound production. However, during experiments involving juvenile rig sharks (Mustelus lenticulatus), also known as spotted estuary smoothhound sharks, researchers made a surprising discovery. These sharks, native to New Zealand, rely on plate-like teeth to crush crustaceans rather than the sharp teeth seen in other species.
Unexpected Clicking Sounds During Experiments
The team conducted behavioral experiments in a large water tank, studying shark hearing. Part of their methodology required temporarily restraining the sharks for brief periods. It was during these handling sessions that researchers first detected the clicking sounds. Intrigued, they sought to determine whether this was a deliberate behavior.
To verify their observations, the scientists placed the sharks in separate tanks and repeated the handling process, this time recording the interactions with underwater microphones. The results confirmed that all tested sharks produced the clicking sounds upon being held. Interestingly, the frequency of these sounds diminished over time, suggesting the sharks adapted to the stimulus.
Potential Purpose of the Clicking Sounds
While some species of rays and skates are known to generate sounds when disturbed, researchers propose that the rig sharks’ clicking noises result from rubbing their teeth together. One theory suggests this could serve as a defense mechanism to momentarily startle predators, such as fur seals. However, the study found no evidence that these sounds function as a distress signal for other sharks, as the clicks’ frequencies exceeded the typical hearing range of sharks.
Future Research and Implications
This discovery opens new avenues for understanding shark behavior and communication. Further studies may explore whether other shark species possess similar sound-producing capabilities and how these findings contribute to our broader knowledge of marine life acoustics.
For more details, refer to the original research published in Royal Society Open Science: Carolin Nieder et al, Evidence of Active Sound Production by a Shark, Royal Society Open Science (2025). DOI: 10.1098/rsos.242212