Weird Creature Facts: The Pistol Shrimp
If you've read my article on the bombardier beetle, you already know of one denizen of the animal kingdom that employs a defense mechanism analogous to modern weaponry. Now let's take a look at another favorite of mine: the pistol shrimp. It's a good thing the pistol shrimp only grows to an inch or so long. If it were any bigger, its hunting method would be downright terrifying. This shrimp, you see, has the ability to fire concussion projectiles made out of water.
Depending on the species, the pistol shrimp boasts an enormous claw that can close with incredible force. When the shrimp snaps its claw shut, it creates what is known as a 'cavitation bubble' or an area of extremely low water pressure. The cavitation bubble extends forward at the speed of 60mph and slams into the shrimp's unfortunate prey. The shock of the bubble's strike is strong enough to stun or kill small fish. The stunned prey falls to the ocean floor, where the shrimp pulls it into its burrow and begins to feed.
There's more to the shrimp's high-tech weaponry than this, however. As the cavitation bubble closes, the massive pressure causes an increase in temperature. The temperature inside of the cavitation bubble increases to 4,700° celsius. To put that in perspective, the surface of the sun is about 5505° celsius. The noise produced by this micro-cataclysm can reach 218 decibels. In comparison, a jet engine reaches a measly 140 decibels.
On top of its naturally-occurring sonic death-ray, the shrimp also takes part in an interesting symbiotic relationship with certain species of goby fish. The pistol shrimp has terrible eyesight and cannot see predators approaching. Despite its formidable weaponry, the pistol shrimp is left vulnerable to attacks by fast predators that can take advantage of its poor eyesight. In order to overcome this difficulty, the pistol shrimp stays close by its symbiont, the goby fish. The shrimp rests its antennae on the goby's body. When the goby sees a predator approaching, it warns the pistol shrimp by means of certain bodily movements which act as signals. When the shrimp feels these signals, it retreats, along with the goby, back into their mutually-shared burrow. This allows the shrimp to lay in wait to ambush unwitting fish with its pressure-weapon without fear.
If you enjoyed this article, I have another piece on a deep-sea terror which you may be interested in. My article on the anglerfish explains the creature in depth. Despite lacking the weaponry of the pistol shrimp, is quite frightening in its own way.
Breaking wave image courtesy of publicdomainpictures.net