By Matt McGrathEnvironment Correspondent
A tiny, transparent fish sounds as loud as a jackhammer, scientists in Berlin have discovered.
They were prompted to investigate after a mysterious clicking sound came from the fish tanks in their laboratory.
They found that Danionella cerebri elicits a powerful rhythm in an organ called the fish swim bladder.
In the water near the fish, it hits 140 decibels, which is as loud as a gunshot.
At 12 mm in length, researchers believe the species is the loudest fish ever discovered.
They believe that drumming can be a form of social interaction.
In most parts of nature, large animals are loud and noisy.
It's a different story underwater—the tiny marine species is one of the noisiest ever discovered.
Scientists know that other species, such as the aptly named pistol shrimp, can make loud noises of around 200 decibels when hunting other species.
Danyonella is prized by science because its transparency allows you to see its brain in action and allows researchers to closely study its behavior.
AlamyBut while working with these fish in their lab in Germany, the scientists noticed something different.
“People were walking past fish tanks and could hear these sounds and were wondering where they were coming from,” said Verity Cook, lead author of the study and a PhD student at Charité University in Berlin.
“It turns out they come from fish. And it's unusual because they're so small and so noisy.”
Using an array of microphones and video cameras, the research team was quickly able to work out how loud it was.
“At a body-length distance, about 140 decibels is the amplitude of sound that we believe other fish can perceive,” he told BBC News.
“Sound decreases with distance, so at a distance of one meter, the amplitude is 108 decibels.”
It is still equivalent to the sound of a bulldozer.
Much of this sound is reflected back into the water, so when humans stand near fish tanks, they hear these pulses as a continuous sound.
Although plainfin midshipman and black drum and other fish are noisy, they are all much larger than danionella.
“In terms of communication signals, I can't find another animal that makes this loud noise,” Ms Cook added.
Researchers argue that the drumming technique used by fish is a highly sophisticated tool.
All bony fish have a swim bladder, a gas-filled organ that helps them stay underwater.
Many species use their muscles to drum in this bladder to produce sounds, but Taninella goes several steps further.
When its muscles contract, these pull on the rib cage, which creates tension with the piece of cartilage that sits inside the muscle.
As the cartilage protrudes, it impinges on the swim bladder.
Only males of the species make this sound, and they only do it in company. Some are louder than others.
“We know that when you put eight males together in a large tank, three of them will dominate the sound production and the others will be quiet. So we think there is some sort of hierarchy,” Ms Cook said.
Originating in murky waters in Myanmar, researchers believe it may have played a role in developing the ability to make a loud noise to help them communicate.
“Evolution has come up with many interesting ways to solve many interesting problems,” Ms Cook said.
“We shouldn't assume that we know how things work because of how things work in other species.”
Research has been done Published In Journal, Proceedings of the National Academy of Sciences.
