Alpheidae

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iSnapping shrimp

Alpheus digitalis

Scientific classification

Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Decapoda
Infraorder:	Caridea
Superfamily:	Alpheoidea
Family:	Alpheidae Coutière, 1899

Genera

See text.

Alpheidae is a family of caridean snapping shrimps that typically have large claws. Other common names of these species include pistol shrimps or alpheid shrimps. There are 57 species in this family.

This family of shrimp is generally associated with the pistol goby, or watchman family of gobies. The burrow is built and tended to by the pistol shrimp, while the goby guards him from danger by alerting the blind shrimp.

Social behavior has been discovered in the genus Synalpheus. The species Synalpheus regalis lives inside sponges in colonies that can number over 300 members. All of them are the offspring of a single large female, the queen, and possibly a single male. The offspring are divided into workers who care for young, and the soldiers who protects the colony with their huge claws. Most of the soldiers are males. So far only one social species has been described, but many scientists think it is likely that there are more species in the genus with complex social behaviour that have not yet been found.

1 Snapping effect
2 Genera
3 Taxonomy note
4 References

[edit] Snapping effect

The pistol shrimp snaps a specialized claw shut to create a cavitation wave that generates noise in excess of 200 decibels, capable of killing small fish and breaking glass up to 1.8 metres away. The snap can also produce sonoluminescence from a collapsing bubble, also known as cavitation bubble ^[1]. This has been dubbed "shrimpoluminescence". The light is of lower intensity than the light produced by typical sonoluminescence and is not visible to the naked eye. It is most likely a by-product of the shock wave with no biological significance. However, it is the first known instance of an animal producing light by this effect.

It is thought that when the bubble implodes a very small region momentarily reaches temperatures of several thousand kelvins, comparable to the temperature of the outer layer of the Sun.