Scientists report that one of the world's smallest fish species, which is about the width of an adult human fingernail, can produce a sound as loud as a gunshot.
According to research published in the journal PNAS, males of the genus Danionella cerebrum, a fish around 12 mm in size found in Myanmar streams, generate sounds that exceed 140 decibels (dB). This sound intensity is comparable to the sound of fireworks exploding, rifle shots, jackhammers, or ambulance sirens, and it is even louder than the sound of an airplane taking off (130 dB).
This study shows that the most common mechanism in fish for making sounds involves the vibration of their swim bladders. This organ, which is filled with air, functions to control buoyancy and is controlled through the rhythmic contractions of special muscles.
However, the sound-generating mechanism of the Danionella cerebrum, which has the smallest known brain among vertebrates, remains a mystery. The reason is that the mechanical mechanism involved in the swim bladder does not provide a reasonable explanation for the origin of the sound.
Scientists at Charité University (Germany) have discovered that this fish has a unique sound-generating system, including cartilage, ribs and anti-fatigue muscles. This allows the fish to increase its speed and "drum to create sound" with great force.
The findings show that to create sound, a rib located next to the bladder is moved by a special muscle. Then, the ribs will collide with the swim bladder and make a sound like a drum. The ribs in males are much harder, which explains why females do not make sounds.
According to scientists, this small fish makes such loud sounds to create waves, helping the fish move better in turbid water. It is also a tactic used by male fish to protect their territory or compete for prey with other individuals.