Scientists have unveiled a remarkable discovery about one of the world’s smallest fish, the Danionella cerebrum, which measures approximately the width of an adult human fingernail. Despite its minuscule size, this fish from the streams of Myanmar can produce sounds as loud as a gunshot, exceeding 140 decibels.
The most common method for fish to produce sound involves vibrations of their swim bladder, a gas-filled organ crucial for buoyancy control, driven by rhythmic contractions of specialized muscles. However, the male Danionella cerebrum, boasting the smallest known brain among vertebrates, challenges conventional understanding with its exceptionally loud pulses.
Researchers at Charité University in Berlin conducted a detailed study to unravel the mystery behind the fish’s sound production. They discovered a unique system involving a drumming cartilage, specialized rib, and fatigue-resistant muscle. This mechanism allows the fish to accelerate the drumming cartilage at extreme forces, resulting in rapid and loud pulses that defy its diminutive size.
The paper highlighting this discovery emphasizes its significance in expanding our understanding of animal motion, evolutionary biology, and biomechanics. By uncovering such an extraordinary adaptation, scientists gain insights into the diverse propulsion mechanisms across species.
High-speed video recordings were instrumental in investigating the intricacies of the sound production mechanism. The process involves a rib adjacent to the swim bladder being moved by a specialized muscle into a piece of cartilage. Upon release, the rib strikes the swim bladder, creating the distinctive drumming sound. Notably, the rib is considerably harder in males, explaining why females of the species do not produce sounds.
While the exact purpose of these loud sounds remains uncertain, scientists speculate they could aid navigation in murky waters or serve as an aggressive tactic used by males to deter competition. Further research is needed to delve deeper into the behavioral implications of this unique sound production system in the Danionella cerebrum.
The study revealing this astonishing finding was published in the PNAS journal.