Alpheidae is a family of caridean snapping shrimp, characterized by having asymmetrical claws, the larger of which is typically capable of producing hot shrimps loud snapping sound. Other common names for animals in the group are pistol shrimp or alpheid shrimp. The family is diverse and worldwide in distribution, consisting of about 1,119 species within 38 or more genera.

The two most prominent genera are Alpheus and Synalpheus, with species numbering well over 250 and 100, respectively. When in colonies, the snapping shrimp can interfere with sonar and underwater communication. The shrimp are considered a major source of sound in the ocean. It is distinctive for its disproportionately large claw, larger than half the shrimp’s body. The claw can be on either arm of the body, and, unlike most shrimp claws, does not have typical pincers at the end.

Rather, it has a pistol-like feature made of two parts. A joint allows the “hammer” part to move backward into a right-angled position. Some pistol shrimp species share burrows with goby fish in a mutualistic symbiotic relationship. The burrow is built and tended by the pistol shrimp, and the goby provides protection by watching out for danger.

When both are out of the burrow, the shrimp maintains contact with the goby using its antennae. Eusocial behavior has been discovered in the genus Synalpheus. The species Synalpheus regalis lives inside sponges in colonies that can number over 300. Pistol shrimp have the ability to reverse claws. When the snapping claw is lost, the missing limb will regenerate into a smaller claw and the original smaller appendage will grow into a new snapping claw. Laboratory research has shown that severing the nerve of the snapping claw induces the conversion of the smaller limb into a second snapping claw.

The reversal of claw asymmetry in snapping shrimp is thought to be unique in nature. The claw of the snapping shrimp is a dimorphic addition to the arsenal of the shrimp. The snapping shrimp species will retain the same mate after copulation, making them monogamous. Most females of the Alpheidae species are susceptible to mating.