The Guardian newspaper today, February 27, cited a new study published in the journal PNAS , saying that a male of the Danionella cerebrum species, a fish about 12 mm in size found in streams in Myanmar, produces sounds exceeding 140 decibels (dB).
This volume level is equivalent to an ambulance siren or a jackhammer.
The paper says the most common mechanism in fish for producing sound involves the vibration of their swim bladders. This gas-filled organ controls buoyancy and is controlled through rhythmic contractions of specialized muscles.
Male individual of the genus Danionella cerebrum
THE GUARDIAN SCREENSHOT
However, the sound-producing mechanism of Danionella cerebrum, which has the smallest known brain among vertebrates, remains a mystery, because the muscular mechanism involved in the swim bladder does not provide a plausible explanation for the origin of the sound.
The team used high-speed video recording and then slowed down the footage to observe the mechanism that produces sound.
Scientists at Charité University (Germany) have discovered that this fish has a unique sound-producing system, including cartilage, ribs and fatigue-resistant muscles. This allows the fish to accelerate the "sound drum" with great force.
The discovery suggests that to produce the sound, a rib located next to the bladder is moved by a special muscle. The rib then hits the swim bladder and produces a drum-like sound.
The ribs in males are much stiffer, which explains why females do not make sounds.
Scientists are not yet sure why the fish makes such a loud noise but think it could be to help them navigate murky waters or be an aggressive tactic used by males to gain an advantage over rivals.
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