A tiny water bug that “sings” by rubbing its penis against its belly has been dubbed the loudest animal on Earth — relative to its body size — in a study by French and Scottish scientists.
A species of water boatman, an insect that is common in rivers and ponds across Europe and measures just under 1/12 of an inch (2 mm), has been found to be incredibly loud, according to Discover magazine.
Scientists recorded the Micronecta scholtzi “singing” at up to 99.2 decibels, which is the equivalent of listening to a loud orchestra play while sitting in the front row, the BBC reports.
The average song of M. scholtzi reached 78.9 decibels, comparable to noise level of a ringing phone or a passing freight train.
The insect "sings" by a process called “stridulation,” the act of rubbing two body parts together to create a sound. In this case, the insect rubs a ridge on its penis against its ridged abdomen in what scientists believe is a courtship display to attract a mate.
The team of biologists and engineering experts recorded the insects using underwater microphones, and the study was published in the scientific journal PloS One.
"We were very surprised. We first thought that the sound was coming from larger aquatic species such as a Sigara species [of] lesser water boatmen," engineering expert Dr. James Windmill from the University of Strathclyde in Glasgow told the BBC.
"When we identified without any doubt the sound source, we spent a lot of time making absolutely sure that our recordings of the sounds were calibrated correctly,” he said.
Because the insect lives underwater, most of the sound is lost when transferring from water to air. However, the water bug's song is still loud enough to be heard by a person walking along the banks of a pond or river.
Most of the loudest animals on Earth are also the largest. Blue whale songs can reach 188 decibels, the BBC says.