A tiny water boatman is the loudest animal on Earth relative to its body size, a study has revealed.  
Scientists from France and Scotland recorded the aquatic animal "singing" at up to 99.2 decibels, the equivalent of listening to a loud orchestra play while sitting in the front row.  
The insect makes the sound by rubbing its penis against its abdomen in a process known as "stridulation".  
Researchers say the song is a courtship display performed to attract a mate.  
 
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