A 12 millimeter fish emits a sound as loud as a gunshot. The mystery solved by researchers

Scientists have revealed that one of the world's smallest fish, measuring around 12mm, can make a sound as loud as a gunshot, The Guardian reports.

The sounds emitted by these fish exceed 140 decibels. Photo: Archive

Male Danionella cerebrum, a fish found in waterways in Myanmar, produces sounds that exceed 140 decibels, according to the study published in the journal PNAS, the equivalent of an ambulance siren or a jackhammer.

The most common sound-producing mechanism in fish involves vibrations of the swim bladder – a gas-filled organ used to control buoyancy – driven by rhythmic contractions of specialized “drumming” muscles, the paper says.

However, the mechanism for producing the sound impulses generated by Danionella cerebrum, which has the smallest known brain of any vertebrate, has been a mystery, as muscle mechanisms related to the swim bladder have not provided a plausible explanation for the origin of the sound.

Scientists at the Charite University of Berlin discovered that the fish has a unique sound-producing system involving a drum cartilage, a special nerve and a fatigue-resistant muscle. This allows the fish to accelerate the drum cartilage with extreme forces and generate fast and powerful impulses.

“Understanding this extraordinary adaptation expands our knowledge of animal movements and highlights the remarkable diversity of propulsion mechanisms across species, contributing to the broader understanding of evolutionary biology and biomechanics“, the document states.

The research team used high-speed video footage to investigate the mechanism of sound production.

To produce the sound, a rib that is next to the swim bladder is moved by a special muscle in a piece of cartilage. When the rib is released, it hits the swim bladder and produces the drumming sound. The rib is much harder in males, which explains why females do not make sounds.

Researchers have not been able to find out why the fish make such loud sounds, but have suggested that they may help navigate in murky waters or be an aggressive tactic used by males to warn off rivals.