These Tiny Fish Are Loud as a Gunshot

Often in nature, the larger the animal, the louder the noise. The sperm whale, for instance, can make clicks as loud as 200 decibels, while the elephant can trumpet as loud as 117 decibels. But as we know, nature is full of surprises, and in one such surprise, researchers have discovered the king of trumpeting is beat by an animal smaller than one of its toenails, with the ability to make sounds as loud as a gunshot. Scientists at the Charite University in Berlin were keeping Danionella cerebrum, a species of fish often used in the study of neuroscience, in tanks in their lab when passersby noticed a loud, unexplained buzz. It turned out the sound was coming from the fish. "And it's extraordinary, because they're so tiny and so loud," PhD student Verity Cook tells the BBC.

Scientists soon discovered the males possess "a unique sound production apparatus," according to a study published Monday in PNAS. They contract a muscle, which pulls on a rib, creating tension with cartilage inside the muscle. The cartilage then releases, hitting the gas-filled swim bladder and making a loud noise typically repeated in rapid pulses at 140 decibels. That's as loud as a gunshot, ambulance siren, or jackhammer, the Guardian reports. "That's how loud we believe the sound to be perceived by other fish" at one body length away, Cook, the lead study author, tells the BBC. At a distance of a few feet, "the amplitude is around 108 decibels," or as loud as a bulldozer.

"People were just walking past the fish tanks, and they could hear these sounds," says Cook, noting that because water reflects much of the noise, it sounds like a continuous buzz to humans. "In terms of communication signals, I couldn't find another animal of this size that makes sounds this loud," Cook adds. Indeed, the finding makes Danionella cerebrum one of the noisiest species yet discovered, per the BBC. For comparison, "the loudest human yell was 129 decibels," per USA Today. Scientists speculate that the drumming noise is used for communication, perhaps to warn off rival males or to navigate the murky streams of Myanmar, where the fish live. As Cook tells the BBC, "Evolution has come up with lots of interesting ways to solve lots of interesting problems." (More discoveries stories.)