Pistol shrimp have a unique reputation as one of the ocean’s most intriguing crustaceans. Most are only about the size of your index finger, and they sport asymmetric claws, one of which is much larger than the other and contains the primary mechanism that gives this shrimp its distinctive name.
Unlike most shrimp, the pistol shrimp doesn’t have any pincers at the end of its claw. Instead, the asymmetrically large claw is comprised of a hammer and anvil mechanism that, with the help of two powerful muscles, slams shut at break-neck speeds to create an underwater cavitation bubble. Surrounding water then compresses the cavitation bubble, causing it to implode.
Anyone that has ever witnessed a pistol shrimp in action has probably heard the ‘popping’ sound that it produces under water. This sound is actually the compression of the cavitation bubble, and not the claw closing itself. As this compression takes place, this small space can temporarily reach temperatures of almost 4,000 degrees Celsius, devastating any prey that the pistol shrimp chooses to chase after. Albeit true that this incredibly focused attack needs to be well-placed to have any impact on its prey, the pistol shrimp is particularly good at landing its strike.
It’s also worth noting that a pistol shrimp’s snapping produces quite a bit of noise. The clicking of some pistol shrimp colonies have been measured at nearly 210 decibels, which compares to the loud grinding of a chainsaw at just 120 decibels. In fact, Naval vessels once used pistol shrimp colonies’ snapping to help conceal massive submarine positions from enemy hydrophones.
Indeed, while the pistol shrimp may not look like much at first glance, it’s safe to say that they’ve got a pretty cool trick up their sleeve.