Scientists have reported that one of the smallest fish species in the world, measuring as wide as an adult human fingernail, can produce sounds as loud as gunshots.
According to Oddity Central, Danionella cerebrum was first identified in the 1980s but was only officially recognized in 2021, after researchers discovered slight physical differences between this species and Danionella translucida.
Both fish species are tiny, comparable to a human fingernail, and are so similar that they can only be distinguished under a microscope.
Danionella cerebrum. (Photo: Wikimedia Commons).
Recently, a group of researchers discovered another fascinating characteristic of Danionella cerebrum. This feature not only distinguishes the species from others in the same genus but also elevates it to a high rank on the list of the loudest animals in the world.
The Guardian reported on February 27, citing a new study published in the journal PNAS, that a male specimen of Danionella cerebrum, a fish measuring about 12 mm found in streams in Myanmar, produces sounds exceeding 140 decibels (dB).
This volume level is comparable to that of an ambulance siren or a jackhammer.
The article noted that the most common mechanism for sound production in fish involves the vibration of their swim bladders. This organ, which is not fully filled with gas, functions to control buoyancy and is regulated through the rhythmic contraction of specialized muscles.
Male specimen of Danionella cerebrum. (Screenshot from THE GUARDIAN).
However, the sound production mechanism of Danionella cerebrum, which has the smallest brain known among vertebrate species, remains a mystery. The reason is that the swim bladder-related muscle mechanism does not provide a reasonable explanation for the origin of the sound.
The research team employed high-speed video recording techniques and then slowed down the footage to observe the sound production mechanism.
Scientists at Charité University (Germany) discovered that this fish has a unique sound-producing system, comprising cartilage, ribs, and fatigue-resistant muscles. This allows the fish to accelerate the “drumming sound” with immense force.
The findings indicate that to produce sound, a rib located next to the bladder is moved by a special muscle. Subsequently, the rib collides with the swim bladder and generates a drum-like sound.
The ribs in male fish are significantly harder, which explains why female fish do not produce sound.
Scientists have yet to determine why this fish produces such loud noises but speculate that it may assist in navigating murky waters or serve as an aggressive tactic employed by males to assert dominance over rivals. Alternatively, it could be an aggressive strategy used by males to signal competition during mating.
