Scientists have made an exciting discovery in the underwater world – a tiny, transparent fish that produces a sound as loud as a jackhammer. The fish, known as Danionella cerebrum, caught the attention of researchers when they heard mysterious clicking noises coming from their lab’s fish tanks. Upon investigation, they found that this 12mm long species drums out a powerful rhythm on its swim bladder, producing a sound that reaches 140 decibels, equivalent to a gunshot.
While it is common for larger animals to make louder noises in nature, the underwater realm presents a different scenario. The minuscule Danionella cerebrum has now been identified as one of the loudest fish ever discovered. Other marine creatures like the pistol shrimp are also known for creating loud sounds, reaching up to 200 decibels. However, what makes Danionella unique is its transparency, allowing scientists to observe its brain activity and closely study its behavior.
The researchers initially stumbled upon this phenomenon while working with the fish in their lab in Germany. Verity Cook, the lead author of the study and a PhD student at Charité University in Berlin, explained that people passing by the fish tanks could hear the sounds and were curious about their origin. It was then revealed that the fish themselves were responsible for the noise, which was extraordinary considering their small size.
To determine the exact loudness of the fish’s sound, the research team employed an array of microphones and video cameras. They discovered that at a distance of one body length away, the amplitude of the sound reached around 140 decibels, which is how loud it is perceived by other fish. Even at one meter away, the amplitude remains at approximately 108 decibels, equivalent to the noise made by a bulldozer. When humans stand beside the fish tanks, they hear these pulses as a continuous buzzing sound due to the reflection of sound waves in the water.
Although there are other fish species like the Plainfin Midshipman and the Black Drum that are louder, they are significantly larger than Danionella cerebrum. In terms of communication signals, no other animal of this size has been found to produce such loud sounds. The researchers believe that the drumming mechanism used by the fish is a highly sophisticated instrument.
All bony fish possess a swim bladder, a gas-filled organ that helps them stay underwater. Many species use their muscles to drum on this bladder and produce sounds. However, Danionella takes it a step further. When the fish contracts its muscles, they pull on a rib, creating tension with a piece of cartilage inside the muscle. Upon release, the cartilage strikes the swim bladder, producing the loud sound. Interestingly, only male Danionella produce this sound, and they do so only in the presence of other males. Some males are louder than others, indicating a potential hierarchy within the group.
The researchers speculate that the fish’s ability to make such a loud noise evolved due to its habitat in murky waters in Myanmar. In order to communicate effectively in these conditions, Danionella developed this unique skill. Verity Cook emphasizes that evolution has found various intriguing solutions to different problems and that we should not assume that we understand everything based on how things work in other species.
The study detailing this discovery has been published in the journal Proceedings of the National Academy of Sciences. The findings shed light on the fascinating world of underwater communication and provide valuable insights into the behaviors and adaptations of marine organisms. As scientists continue to explore the depths of our oceans, who knows what other remarkable discoveries await us?