The loudest creature on Earth, measuring just 2 millimeters, "screams" without a mouth (video).

When discussing the loudest animal on Earth, one might assume it is something particularly large. However, scientists caution that this assumption is misleading. In reality, the record holder for loudness on the planet, at least relative to body size, is the tiny water boatman, according to IFLScience.

The tiny water boatman (Micronecta scholtzi) measures just over 2 millimeters in length and resembles a flea or a stink bug. However, in 2011, scientists named it the loudest sound producer relative to its size. This finding was presented at the annual conference of the Society for Experimental Biology.

Equally fascinating is the fact that these tiny water boatmen actually produce their sounds without using their mouths. When a water boatman wants to attract attention, it extends its penis. Researchers note there is a term for this action — "stridulation," which refers to rubbing body parts together to create sound. Members of this species employ this method in a unique way: the water boatman uses its organ as a "violin bow."

Researchers indicate that the stridulation of the water boatman can reach up to 99.2 decibels and produces sound at a frequency of 10 kHz, which falls within the range of human hearing. Simply put, we are capable of hearing the "trills" of the tiny water boatman.

According to Dr. James Windmill from the University of Strathclyde, even though 99% of the sound is lost when transmitted from water to air, the song of the water boatman is so loud that it can be heard by a person walking along the shore, even if the boatman is at the bottom of the river.

Scientists have also discovered that boatmen use their songs to attract mates. Dr. Windmill states that despite the ability of this species to produce such loud sounds, they do so in a very tiny space. Researchers are still baffled as to how they achieve this.

Researchers believe that understanding how these tiny creatures can produce such loud sounds is significant for technology and biomimetics. From a biological perspective, this work may also be useful for conservation, as recordings of insect sounds can be utilized for monitoring biodiversity. From an engineering standpoint, understanding this process could be applied to acoustic technologies.