Alpheidae
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 Alpheus digitalis
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Acanthanas |
Alpheidae is a family of caridean snapping shrimp characterized by having asymmetrical claws, the larger of which is typically capable of producing a loud snapping sound. Other common names of these species include pistol shrimp or alpheid shrimp.
The family is diverse, and is worldwide in distribution, consisting of about 600 species within 38 or more genera.[1] The two most prominent genera are Alpheus and Synalpheus, with species numbering well over 250 and 120, respectively.[2][3] Most snapping shrimp dig burrows and are common inhabitants of coral reefs, submerged grass flats, and oyster reefs. While most genera and species are found in tropical and temperate coastal and marine waters, Betaeus inhabits cold seas and Potamalpheops is found only in freshwater caves.
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[edit] Ecology
Some snapping shrimp species share burrows with goby fishes in a symbiotic relationship. The burrow is built and tended by the snapping 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 antenna. The goby, having the better vision, alerts the shrimp of danger using a characteristic tail movement, and then both retreat into the safety of the shared burrow.[4] So far this association has been observed in species that inhabit coral reef habitats.
Social behavior has been discovered in the genus Synalpheus. The species Synalpheus regalis lives inside sponges in colonies that can number over 300 members.[5] 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 protect the colony with their huge claws. Most of the soldiers are males. So far only a few social species have been described, but many scientists think it is likely that there are more species in the genus with complex social behavior that have not yet been found.
Snapping shrimp have also been noted for their ability to reverse claws. When the snapping claw is lost, the missing limb will regenerate into a smaller claw and the original small claw will grow into a new snapping claw. Laboratory research has shown that severing the nerve of the snapping claw induces the conversion of the small claw, resulting in a shrimp with two large claws, but this phenomenon of claw symmetry in snapping shrimp has only been documented once in nature.[6]
[edit] Snapping effect
The snapping shrimp competes with much larger animals, like the sperm whale and beluga whale, for the title of 'loudest animal in the sea'. The shrimp snaps a specialized claw shut to create a cavitation wave that generates acoustic pressures of up to 80 kPa at a distance of 4 cm from the claw. The pressure wave is strong enough to kill small fish.[7] It corresponds to a zero to peak pressure level of 218 decibels relative to one micropascal (dB re 1 μPa), equivalent to a zero to peak source level of 190 dB re 1 μPa at the standard reference distance of 1 m. Au and Banks measured peak to peak source levels between 185 and 190 dB re 1 μPa at 1 m, depending on the size of the claw.[8] Similar values are reported by Ferguson and Cleary.[9] The duration of the click is less than 1 millisecond.
The snap can also produce sonoluminescence from a collapsing cavitation bubble. As it collapses, the cavitation bubble reaches temperatures of over 5000 K.[10] 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.
[edit] Taxonomy note
The problematic genera Pterocaris and Yagerocaris were thought to occupy uncertain positions within the family. However, Anker et al., (2006) provide a comprehensive phylogenetic study of the Alpheidae which supports monophyly of the family, and includes these two genera.[1]
[edit] External links
- Pistol Shrimp capturing prey Video (w/ embellished info)
- How snapping shrimp snap University of Twente
- Article on Pistol Shrimp going into physical details
[edit] References
- ^ a b A. Anker, S. T. Ahyong, P. Y. Noel, and A. R. Palmer (2006). Morphological phylogeny of alpheid shrimps: parallel preadaptation and the origin of a key morphological innovation, the snapping claw. Evolution 60 (12): 2507–2528.
- ^ W. Kim & L. G. Abele (1988). The snapping shrimp genus Alpheus from the Eastern Pacific (Decapoda: Caridea: Alpheidae). Smithsonian Contributions to Zoology 454: 1–119.
- ^ F. A. Chase, Jr. (1988). The Caridean Shrimps (Crustacea: Decapoda) of the Albatross Philippine Expedition, 1907–1910, Part 5: Family Alpheidae. Smithsonian Contributions to Zoology 466: 1–99.
- ^ Karplus, I. (1987). The association between gobiid fishes and burrowing alpheid shrimps. Oceanography and Marine Biology Annual Review 25: 507–562.
- ^ J. E. Duffy (1996). Eusociality in a coral-reef shrimp. Nature 381: 512–514.
- ^ M. R. McClure (1996). Symmetry of large claws in snapping shrimp in nature (Crustacea: Decapoda: Alpheidae). Crustaceana 69 (7): 920–921.
- ^ M. Versluis, B. Schmitz, A von der Heydt, and D. Lohse (2000). How Snapping Shrimp Snap: Through Cavitating Bubbles. Science 289: 2114–2117.
- ^ W. W. L. Au & K. Banks (1998). The acoustics of the snapping shrimp Synalpheus parneomeris in Kaneohe Bay. J. Acoust. Soc. Am. 103: 41–47.
- ^ B. G. Ferguson & J. L. Cleary (2001). In situ source level and source position estimates of biological transient signals produced by snapping shrimp in an underwater environment. J. Acoust. Soc. Am. 109: 3031–3037.
- ^ D. Lohse, B. Schmitz & M. Versluis (2001). Snapping shrimp make flashing bubbles. Nature 413 (6855): 477–478. doi:10.1038/35097152.
