MOSCOW, March 14. Male fish of the species Danionella cerebrum produce the loudest sound of any fish of similar size, scientists from the Charité Medical University in Berlin reported in an article for the scientific journal Proceedings of the National Academy of Sciences.
“Such an amplitude is not at all typical for animals of this size. To explain the mechanism of such loudness, we filmed three individuals in an aquarium using supersonic filming on cameras that take up to 8 thousand pictures per second. The sound is generated so quickly that we saw a reduction in the swimming bubble on only one of them,” the scientists said.
Since no known muscle can contract so quickly, the team of researchers had to resort to microcomputed tomography. They managed to find out that the fish have special muscles. When they contract, they pull on the so-called tympanic cartilage inside the muscle. When it relaxes sharply, it hits the swim bladder, then returns to its original position.
Scientists believe that this ability helps the fish interact, since they live in murky waters with a visibility range of no more than 5 centimeters. At a distance of a centimeter, the sound power is 147 decibels. For comparison, the volume of a jet engine at a distance of 100 meters is “only” 140 dB. Moreover, the organs that generate this sound are located in close proximity to the hearing aid of the fish.
“It remains a mystery how these fish manage not to go deaf,” scientists are surprised.
The genus of ray-finned fish Danionella from the carp family is considered one of the smallest vertebrates in the world. The length of an adult is 10-12 millimeters. It has no scales, and its body and head are so transparent that a living brain is visible — the smallest of all known vertebrate species. Due to its simplified anatomy, Danionella has traditionally attracted the attention of scientists, who consider it as one of the most primitive representatives of vertebrates and use its example to study the formation of the latter’s brain.
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