As far as underwater noisemakers go, you may be inclined to think that the ocean’s larger animals, like humpback whales, are responsible for the vast majority of marine noise, but you may be surprised to learn that one of the strongest contenders for loudest oceanic animal could easily fit into the palm of your hand: the pistol shrimp.
The pistol shrimp belongs to a saltwater family of shrimp, called Alpheidae, that lives burrowed in the coral reefs and substrates of the planet’s warmer waters. Also called a snapping shrimp or cracker, it measures less than an inch in length, but is equipped to deal with both predator and prey through an oversize claw comprised of two parts that work together like a pistol to snap shut when necessary.
This snapping mechanism creates a cavitation bubble, which travels upward at an incredibly high speed. While rapidly rising, the bubble pops, producing a sound that can reach as much as 218 decibels! For comparison, the average street noise measures about 70 decibels; anything over 120 dB is considered deafening. This eardrum-piercing noise stuns its prey instantly, giving the shrimp enough time to capture and kill the hapless victim before it even knew what hit it. The noise can kill small fish, and has broken glass jars in tests performed on the phenomenon. Although it presents no biological use, temperatures upwards of 4,200 C have been recorded when the bubble collapses, which is only 800 C less than the temperature of our sun!
Because the target prey of the pistol shrimp is smaller crustaceans and fish, it seems logical that the smallest of sea creatures would want to stay clear of this shrill shrimp, but this is not the case. The pistol shrimp has adapted a wonderfully symbiotic relationship with many species of gobies, friends, with whom it shares the home. As the shrimp is almost blind, the goby offers a watchful vigil for the shrimp, alerting it to the presence of predators with a wiggle of its fin, at which point they both retreat into the burrow. When the pistol shrimp senses prey with its long antennae, it snaps its mighty claw and draws the prey into its burrow, where it will share bits with the goby. When it comes time to turn in, both occupy the burrow together until it’s time to start the day anew.
In the unlikely event the pistol shrimp wants to emerge further from the burrow, it stays in touching contact with the watchful goby. He looks after the goby by using sand to close up the entrance of their burrow in order to keep them safe at night, and cleaning parasites off of the goby’s fins. The goby even gets maternity support, as the pistol shrimp allows the goby to safely store their eggs in the shared burrow, hidden away from predators.
Even if the pistol shrimp is a loud little critter, we have to say he seems like an okay guy all around. Check out this beautifully shot footage of the underwater search for the ubiquitous, yet surprisingly elusive pistol shrimp.
