Some of Earth’s fish are known for their Herculean strength and funky vision. For the less than one inch long Danionella cerebrum, it’s their loud vocals. This tiny fish in the minnow and carp family can produce sounds louder than an airplane taking off as perceived by human ears at a distance of 328 feet, according to a study published February 26 in the journal Proceedings of the National Academy of Sciences (PNAS).
[Related: World’s oldest living aquarium fish could be 100 years young.]
Danionella cerebrum is a small and translucent fish that was first discovered in 2021 in shallow and murky mountain streams in southern and eastern Myanmar. It has the smallest known vertebrate brain, but can hold its own with other members of the animal kingdom of all sizes when it comes to making noise. Small snapping shrimp can produce popping sounds of up to 250 decibels, while large elephants use their trunks to make noises up to 125 decibels.
“This tiny fish can produce sounds of over 140 decibels at a distance of 10 to 12 millimeters [about 0.4 inches],” Ralf Britz, a study co-author and ichthyologist at the Senckenberg Natural History Collections in Germany, said in a statement. “This is comparable to the noise a human perceives of an airplane during take-off at a distance of 100 meters [328 feet] and quite unusual for an animal of such diminutive size.”
For Danionella cerebrum, its impressive vocals come from sound-generating apparatus that helps them communicate with one another through cloudy waters. An international team of researchers took high-speed videos of groups of fish in a tank to observe how this specialized muscle works to make noise. It is made up of drumming cartilage, a specialized rib, and even some fatigue-resistant muscle.
To make noise, it hits the drumming cartilage against a gas-filled organ that helps them stay underwater called a swim bladder. This drumming produces rapid pulses in high and low frequencies. The higher frequency pulses are generated by compressing the swim bladder from the left and right in an alternating pattern. Lower frequency pulses are created with repeated compressions on the same size of the fish’s body. According to the study, no other fish is known to generate sound from repeated unilateral muscle contractions.
[Related: How echolocation lets bats, dolphins, and even people navigate by sound.]
The team assumes that competition between males in a very dark and murky environment has contributed to the development of this special noise making organ. Understanding the extraordinary adaptation of Danionella cerebrum is helping scientists learn more about animal movement and all of the different propulsion mechanisms different species use.
See-through fish like zebrafish are often used as a model organism in biomedical research since it is possible for scientists to easily study their organs and larvae since they are transparent. The fish in the Danionella genus like Danionella cerebrum offers scientists a similar opportunity to compare how the mechanisms behind sound generation differ between species.
“The sounds produced by other Danionella species have not yet been studied in detail,” the team writes. “It would be interesting to learn how their mechanism of sound production differs and how these differences relate to evolutionary adaptation.”
