Alpheidae - Snapping Shrimps
Snapping shrimps are also known as "pistol" shrimps. They are noted for having one oversized claw (usually larger than ½ the body) that is capable of making loud snapping sounds. As the shrimp snaps its fingers shut, a jet of water spurts out, sometimes at speeds of up to 60 mph. The jet causes a low pressure bubble to form. As the bubble collapses, it produces a burst of sound, light and heat for a fraction of a second. The high speed sound can stun larger fishes and kill smaller organisms. The heat generated is nearly equal to the heat given off the sun's surface.
Most snapping shrimps dig burrows and can be found around coral reefs, seagrasses and oyster beds. They are known to share their burrows in a symbiotic relationship with other organisms, most notably gobies. The goby (which has better eyesight than the snapping shrimp) keeps watch for danger and signals the snapping shrimp when danger approaches. Then they both dive into their shared burrow. Snapping shrimps are also known to reverse claws. When the snapping claw is lost, it grows back into a smaller claw, and the minor claw starts growing into the new snapping claw. These shrimps are small, not reaching over 5 cm (2 in) so are of very little commercial value, though they are sometimes used as bait.