Small, Hot, and Loud
Front row seats at a rock concert may make your ears ring — the 120-plus decibel sound output from the stage can put you at risk for tinnitus (ringing in the ears), which typically begins at 127 decibels. Gunshots register at 133 decibels. A Boeing 727, at takeoff, creates sound at about 165 decibels. Blow up a pound of TNT from a few yards away and you’ll be near 180 decibels. And when something breaks the sound barrier, that sonic boom weighs in at 213 decibels.
The pistol shrimp, pictured above, laughs at such silence.
The shrimp are, true to their name, tiny — no more than the size of a finger, per National Geographic. But unlike most shrimp, pistol shrimp have — proportionally speaking — a massively enlarged claw protruding from their bodies. And while these shrimp use their claw to subdue their prey, they do not do so in the standard, pinch-and-grab sense. Rather, they use the claws to make mind-boggling loud noises. Literally.
When the shrimp snaps its claw shut, it creates a bubble. The bubble — and not the snapping of the claw itself — is responsible for a sound which, according to the Daily Mail, can hit 218 decibels. Nat Geo explains how the sound is created: “When the claw snaps shut, a jet of water shoots out from a socket in the claw at speeds of up to 62 miles (100 kilometers) an hour, generating a low-pressure bubble in its wake. As the pressure stabilizes, the bubble collapses with a loud bang.” On top of that, the bubble’s burst creates a flash of light which, while not visible to the naked eye, can be detected with the proper instruments. As a study published in Nature concluded, this necessarily leads to extremely high temperatures — around 5,000 Kelvin. (The temperature of the Sun’s surface is believed to be about 6,000 Kelvin, for comparison’s sake.)
The entire event happens in a split second, requiring high speed cameras in order for us to study this curiosity of nature. In that split second, however, the shrimp accomplishes its goal. The claw acts like a gun — hence the name of the shrimp — and extreme sound and pressure from the claw’s snapping action is its ammunition. The “bullet” stuns other shrimp, which the pistol shrimp then drags back into its burrow and eats for dinner.
A video of the pistol shrimp’s claw in action — with cheesy sound effects replacing the actual sound — can be seen here.
From the Archives: Indiana Jones and the Sonic of Boom: Another really loud noise from an unexpected source.
Related: 48 ounces of shrimp.
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