Photo: Kim Fleming (Flickr)
What is the loudest animal on earth? A great blue whale? How about a lion roaring?
Blue whales produce one hundred eighty eight decibels of sound. That’s louder than a one hundred fifty decibel rock concert, which can damage hearing. But the loudest animal, relative to its body size, is a tiny insect called the water boatman.
Water boatmen can be found worldwide in fresh and brackish water. They are oval shaped, gray insects with oar like hind legs. They use those legs to paddle along the surface of ponds, lakes and rivers, but the half inch insects don’t live on the water’s surface. Since they don’t have gills, they must swim to the surface for air to breathe.
They are able to carry air bubbles against their abdomens or under their wings. Using those bubbles like diving tanks, they spend most of their time eating algae and hanging out on plants.
Males compete using songs to attract mates by rubbing their genitalia against ridged abdomens in a process called stridulation. The area they use is only about the width of a human hair, but they sure can make plenty of sound. At over ninety nine decibels, they are almost as loud as a subway train or a chain saw.
So Loud Yet So Quiet
So why don’t people notice how loud these tiny insects are? It all has to do with the way sound travels across the water air interface. Water boatmen only sing their songs below the water’s surface.
Fortunately, for people taking leisurely strolls next to streams or ponds, ninety nine percent of the sound is lost when sound waves move from water into air. The songs of the water boatman can be heard coming from the water, but they’re not loud enough to spoil someone’s hike.