In the depths of Southeast Asia’s freshwater streams, a tiny creature—barely the length of a fingernail—holds a fascinating secret. At just 12 mm long, Danionella cerebrum seems unassuming, a translucent fish that blends seamlessly into the waters it occupies.
But don’t let its size fool you.
This otherwise unremarkable fish has an extraordinary superpower: It produces sounds exceeding 140 decibels. In human terms, a sound of this level can easily rival the roar of a jet engine taking off a mere 100 meters away from you.
A See-Through Fish That You Can’t Miss
Danionella cerebrum is native to shallow, freshwater streams of Myanmar. These environments are known for their murky waters, where the fish blends into its surroundings with its near-invisible body, keeping it safe from meandering predators. These waters are teeming with life, and while larger species may draw more attention, this wily little fish occupies its own unique niche.
Danionella cerebrum may escape the wandering eye with ease, but it might not fare as well against a keen ear in its surroundings. These fish can produce sounds of high amplitude exceeding 140 decibels at the distance of its body length, according to a February 2024 study published in the PNAS.
For comparison, a normal conversation between humans reaches about 60 decibels. A jackhammer on a construction site hits around 120 decibels.
Now, noisy animals on our planet are not unheard of—take the Gulf corvina (Cynoscion othonopterus), whose collective calls can reach 200 decibels, or the white bellbird (Procnias albus), known for one of the loudest bird calls at an impressive 125 decibels. But what makes this particular discovery so intriguing is that all this sound is generated by a simple 12-mm frame.
A Sound-Producing Machine That Speaks For Itself
For a frame so small, the ability to produce sounds of such high amplitudes lies in a unique sound production apparatus that sets Danionella cerebrum apart from most of its aquatic peers. And all it takes is a fundamental combination of bone, muscle, and cartilage working together to drum against the fish’s swim bladder, producing the loud noise.
- Drumming cartilage. This structure acts like a drumstick, striking the swim bladder during muscle contractions, which produces the loud sounds.
- Specialized rib. The fifth rib is pulled forward during muscle contractions, which creates tension on the drumming cartilage, before the cartilage is released to strike the swim bladder.
- Muscle adaptations. The muscles associated with this apparatus are capable of exerting extreme forces and adapted for low fatigue, supporting the production loud sound pulses over long intervals.
But sound production isn’t just about volume. The fish’s fatigue-resistant muscles are adapted to sustain these rapid muscle contractions, allowing the fish to produce clicks at repetition rates of up to 100 Hz. The result is a rapid burst of sound that cuts through the underwater world like a shockwave, making this tiny fish one of the loudest creatures for its size.
Unearthing The Voice Behind The Noise
For Danionella cerebrum, these loud clicks are more than just noise—they are critical tools for survival. Sound plays an essential role in the social and reproductive behaviors of the species, particularly during mating rituals. Researchers have found that the males’ vocal activity tends to peak during midday, correlating with periods when females produce the most viable eggs.
The acoustic signals help males attract females and assert dominance over rivals. In an underwater environment where visibility is often limited, sound provides a way for these fish to communicate efficiently, ensuring that males can broadcast their presence across a wide range. The louder the click, the more likely it is to capture the attention of potential mates.
But mating isn’t the only reason these tiny fish roar. The loud sounds may also serve as a deterrent to predators. In the fish’s clear-water habitat, where it might otherwise be vulnerable due to its small size, such high-volume clicks could confuse or startle predators, buying the fish precious time to escape.
The extraordinary acoustic abilities of Danionella cerebrum have made it the focus of research in fields like neuroscience and evolutionary biology. Because of its transparent body, scientists can study the fish’s neural pathways without invasive surgeries, making it a valuable model for understanding how vertebrates produce and process sound.
As research into Danionella cerebrum continues, scientists hope to gain deeper insights into the broader principles of animal communication. The species serves as a reminder that even the smallest creatures can have an outsized impact on our understanding of the natural world.
While the Danionella cerebrum seems harmless now, the noises alone could be scary when heard in the wild. How do the mysteries of the animal world make you feel? Find out where you stand on the Fear of Animals Scale.
