Pistol Shrimp Pack Some Serious Heat

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When I’m not blogging for mental_floss, I can usually be found wearing bright orangerubber pants and gutting, cutting and selling fish at my local Whole Foods (and winning awards for it). Sometimes, my two worlds collide and I find some fascinating stuff involving my ocean-dwelling friends that begs for a blog post. This is one of those times.

The 500+ species of pistol shrimp around the world have one “normal-sized” claw (that is, proportional to their body, the way most shrimp do) and one claw that is about half the size of their bodies. This oversized claw stays open until the shrimp, while defending itself from a predator or hunting for a meal, snaps it closed.

Closing the claw results in the creation of a powerful a powerful, 60mph jet of water and, in its low-pressure wake, a cavitation bubble. When this bubble collapses, it produces 1) a bright flash of light that lasts for a fraction of a second, 2) sound pressures of up to 11.74 psi at a distance of 4 cm from the claw, 3) interior temperatures reaching over 4,000 degrees Fahrenheit, and 4) a loud “pop” that can register at 218 decibels (Here’s a little chart to put that in perspective for you).

A “shot” from a pistol shrimp claw can stun or even kill small marine animals at close proximity, allowing the shrimp to escape danger or consume its prey.

The resulting shock wave easily stuns and kills small fish. Researchers who study—and have been shot at by—pistol shrimp say the pain is not unlike the effect of getting hit by a rubber band gun.

More fascinating than the shrimp’s defenses are the way some of them work with goby fish. The goby has better eyesight than the shrimp, so the shrimp keep in constant physical contact with the fish by resting their antennae on the fish’s tail. The shrimp takes any sudden movement on the part of the goby as a sign of danger, and both fish and shrimp head for the shrimps burrow. With the fish having played watchman, the shrimp then holds up its end of the bargain by acting as an armed guard until the danger has passed.

You can see the pistol shrimp in action here (with over the top sound and video editing)…

...and here (without any sonic embellishment)…

October 12, 2010 - 10:14am
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