It turns out that you don't need to be a very large or very strong creature to make really loud sounds. For this, it is not even necessary to have special organs - moreover, until recently, scientists generally assumed that creatures with a soft body were not capable of making noise in principle - there was simply nothing. But Leocratides kimuraorum, a small marine worm, has radically changed the understanding of this issue.
The polychaete worm Leocratides kimuraorum was discovered only in 2017 by Japanese scientists who studied sea sponges. They are the main food of these worms, but due to the small size of predators, only 2.9 mm in length, several individuals often appear on one sponge at the same time. A fierce struggle for the power source unfolds between them, and their main instrument for battle is sound impulses.
In laboratory conditions, scientists managed to study this process in detail. As soon as two worms collide, they turn towards each other with their mouth openings. The worm pumps up an air bubble in the pharynx, and then with an effort "bursts" it, releasing a shock wave outward. At the same time, the sound power reaches 157 dB, and the conflicting worms are thrown in different directions, which ends the quarrel. Scientists believe that this is a special kind of communication between them.
For comparison, before that, the loudest of the small creatures was considered the clicker crab, whose hunting claw can click with a volume of up to 189 dB. However, the mechanism of sound formation in this case is fundamentally different; therefore, crayfish clicks can be heard with an ordinary ear. For an outside observer, worms are very quiet, and the strength of the sound they emit was measured only with the help of instruments, which is why they remained unknown to science for so long.