Water Insect Sets Noise Record With 'Singing Penis'

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Water Insect Sets Noise Record With 'Singing Penis'

Wed, 12/10/2011 - 22:13
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Study reveals water boatman is the loudest animal on the planet relative to its body size. In terms of decibels, tiny insect is louder than a sperm whale.

The loudest penis is that of a tiny European species of aquatic freshwater insect.

In a recent study published in the journal PLoS One, French and Scottish scientists have discovered that the 2mm long water boatman Micronecta scholtzi make the loudest sounds of any animal on earth relative to its body size. Although the sperm whale may be louder in sheer terms of decibels, when compared to size, the water boatman has all other animals beat.

Using specialist underwater microphones, the aquatic animal was recorded "singing" at up to 99.2 decibels, the equivalent of listening to a loud orchestra play while sitting in the front row. To produce the intense sound, water boatmen "stridulate" by rubbing a ridge on their penis across the ridged surface of their abdomen.

"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," said engineering expert Dr James Windmill from the University of Strathclyde, Glasgow.

"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." What makes M. scholtzi extraordinary is that the area they use to create sound only measures about 50 micrometres across, roughly the width of a human hair.” We really don't know how they make such a loud sound using such a small area," said Dr Windmill.


The question of how the animals physically make such a loud call remains a mystery. In many insects, song volume is limited because predators would hear them, but observations suggest that M. scholtzi lack auditory predators. It is believed that sexual selection could be the reason why the insects' songs reach such high amplitude.

“We assume that this could be the result of a runaway selection," according to biologist and co-author Dr. Jerome Sueur from the Museum of Natural History, Paris." Males try to compete to have access to females and then try to produce a song as loud as possible potentially scrambling the song of competitors."

“The song is so loud that a person walking along the bank can actually hear these tiny creatures singing from the bottom of the river.”

— Dr. James Windmill