Pistol Shrimp

Alpheidae, commonly called snapping shrimp, pistol shrimp or cracker shrimp, is a family of the shrimp infraorder Caridea distinguished by asymmetrical claws, one of them greatly enlarged; roughly half of its species actually lack the snapping ability and are termed non-snapping shrimp. The family, established by Rafinesque in 1815, contains more than six hundred twenty recognised species across fifty two genera, with Alpheus and Synalpheus the most diverse. Snapping shrimp typically measure three to five centimetres long, and in the snapping species a joint lets the claw's hammer section cock backward before releasing to snap shut, generating a cavitation bubble that collapses at speeds up to twenty five metres per second and produces an acoustic pulse loud enough to stun small prey and interfere with underwater sonar and communication. They live worldwide in coral reefs, seagrass flats and oyster reefs, most commonly in tropical and temperate waters, though some genera inhabit cold seas or freshwater caves. Many species form mutualistic burrow-sharing partnerships with goby fish, and some Synalpheus species live in eusocial colonies of more than three hundred individuals inside sponges, organised around a single breeding queen.