Praunus flexuosus
{{Short description|Species of crustacean}}
{{Speciesbox
| image = Praunus flexuosus (Gebogene Schwebegarnele, chameleon shrimp) (28691591852).jpg
| genus = Praunus
| species = flexuosus
| authority = (O. F. Müller, 1776)
}}
Praunus flexuosus, known as the chameleon shrimp, is a species of opossum shrimp found in European waters. It reaches {{convert|26|mm|abbr=on}} long, with a distinctly bent body, and closely resembles Praunus neglectus. It lives in shallow water and tolerates a wide range of salinities. It is found from northern France to the Baltic Sea, and was introduced to North America in the mid 20th century.
Description
Praunus flexuosus is a long, slender animal, with a pronounced bend in the abdomen. It reaches sexual maturity at a length of around {{convert|18|mm}}, but can go on to attain a length of {{convert|26|mm|abbr=on}}. Its colouration is highly variable, ranging from brown or red to green, which accounts for its common name of "chamaeleon shrimp".{{cite book |author=Nellie Barbara Eales |year=1967 |title=Littoral Fauna of the British Isles |publisher=Cambridge University Press |isbn=978-0-521-04862-0 |url=https://books.google.com/books?id=SBY9AAAAIAAJ&pg=PA122}}
Praunus flexuosus is very similar to the related species P. neglectus. The two can be differentiated by the following characters:
| class="wikitable" |
! Character !! P. flexuosus !! P. neglectus | ||
| Body length | 25–26 mm (1.0 in) | {{convert|20|mm|1|abbr=on}} |
| Colour | black to colourless | usually grass green |
| Setae on antennal scale and uropods | colourless | violet or reddish purple |
| Antennal scale length | >3× peduncle | <3× peduncle |
| Antennal scale shape | 7–8× as long as broad | 5× as long as broad |
| Apex of antennal scale | shorter than spine terminating outer margin | longer than spine terminating outer margin |
| Tarsus of thoracic limbs 3–7 | 6 segmented | 5 segmented |
| Tarsus of thoracic limb 8 | 5 segmented | 4 segmented |
| Lateral margins of telson | 21–27 small spines | 18–20 larger spines |
| Cleft in telson | widely open, {{frac|1|6}} of telson length | proximally narrow, {{frac|1|5}} of telson length |
Taxonomy
Praunus flexuosus was the first mysidacean species ever to be formally described, when Otto Friedrich Müller described it under the name Cancer flexuosa in 1776.{{cite book |author=Karl J. Wittmann |year=1999 |chapter=Global biodiversity in Mysidacea, with notes on the effects of human impact |pages=511–525 |url=https://books.google.com/books?id=msw2BgcugkcC&pg=PA512 |editor=Frederick R. Schram & J. C. von Vaupel Klein |title=Crustaceans and the Biodiversity Crisis: Proceedings of the Fourth International Crustacean Congress, Amsterdam, the Netherlands, July 20–24, 1998 |volume=12 |series=Crustacean Issues |publisher=Brill |isbn=978-90-04-11387-9}}
Distribution and ecology
Praunus flexuosus lives along the coast of the north Atlantic Ocean between 40° north and 71° north, and in the Baltic Sea.{{cite web |url=http://species-identification.org/species.php?species_group=crustacea&id=65 |title=Praunus flexuosus |work=Macrobenthos of the North Sea – Crustacea |editor1=Mario de Kluijver |editor2=Sarita Ingalsuo |access-date=July 20, 2011}} There is only one doubtful record from further south than Roscoff. It is "the only documented non-native marine zooplankton species established on the East Coast [of North America]".{{cite book |editor1=Bella S. Galil |editor2=Paul F. Clark |editor3=James T. Carlton |year=2011 |title=In the Wrong Place – Alien Marine Crustaceans: Distribution, Biology and Impacts |volume=6 |series=Invading Nature |publisher=Springer |isbn=978-94-007-0590-6 |chapter=Marine crustacean invasions in North America: a synthesis of historical records and documented impacts |pages=215–250 |author=Gregory Ruiz |author2=Paul Fofonoff |author3=Brian Steves |author4=Alisha Dalhstrom |url=https://books.google.com/books?id=e0vDFQ3yQzcC&pg=PA221}} It was first discovered in North America in 1960, on the north side of Cape Cod,{{cite journal |author=Roland L. Wigley |year=1963 |title=Occurrence of Praunus flexuosus (O. F. Müller) (Mysidacea) in New England waters |journal=Crustaceana |volume=6 |issue=2 |page=158 |doi=10.1163/156854063X00534}} and has since colonised as far north as Nova Scotia.{{cite book |author=Kenneth L. Gosner |year=1999 |title=A Field Guide to the Atlantic Seashore: From the Bay of Fundy to Cape Hatteras |volume=24 |series=Peterson Field Guide |publisher=Houghton Mifflin Harcourt |isbn=978-0-618-00209-2 |chapter=Mysid shrimps |pages=229–230 |url=https://books.google.com/books?id=E1UQ9VEX7qAC&pg=PA230}} This colonisation may have occurred after P. flexuosus was transported as a fouling animal on ships' hulls during the Second World War. It was only discovered around the coast of Iceland in 1970, but has since proved to be common along Iceland's south-west coast.{{cite journal |author=Olafur S. Astthorsson |year=1987 |title=Records and life history of Praunus flexuosus (Crustacea: Mysidacea) in Icelandic waters |journal=Journal of Plankton Research |volume=9 |issue=5 |pages=955–964 |doi=10.1093/plankt/9.5.955}} This introduction may also have been facilitated by wartime convoys (see Battle of the Atlantic).
Praunus flexuosus can tolerate salinities of 2‰–33‰.{{cite journal |author1=D. S. McClusky |author2=V. E. J. Heard |name-list-style=amp |year=1971 |title=Some effects of salinity on the mysid Praunus flexuosus |journal=Journal of the Marine Biological Association of the United Kingdom |volume=51 |issue=3 |pages=709–715 |doi=10.1017/S0025315400015083}} It is often found on algae, and is most closely associated with the seaweed Fucus vesiculosus.{{cite journal |author1=E. Lindén |author2=M. Lehtiniemi |author3=M. Viitasalo |name-list-style=amp |year=2003 |title=Predator avoidance behaviour of Baltic littoral mysids Neomysis integer and Praunus flexuosus |journal=Marine Biology |volume=143 |pages=845–850 |doi=10.1007/s00227-003-1149-x |url=http://www.helsinki.fi/~elinden/projektisivusto/Lindenetal.pdf |format=PDF}} It lives in shallow water, and is often found around artificial constructions, such as docks.{{cite book |editor=P. J. Hayward & John Stanley Ryland |year=1995 |title=Handbook of the Marine Fauna of North-west Europe |publisher=Oxford University Press |isbn=978-0-19-854055-7 |author1=P. J. Hayward |author2=M. J. Isaac |author3=P. Makings |author4=J. Moyse |author5=E. Naylor |author6=G. Smaldon |chapter=Crustaceans |pages=289–461 |url=https://books.google.com/books?id=sZ8mdRT4jbIC&pg=PA334}} It is an omnivore, feeding on debris and preying on small crustaceans, especially harpacticoid copepods, but consumes a greater proportion of macrozooplankton than other common littoral mysids, such as Neomysis integer and Praunus inermis.{{cite journal |author1=Maiju Lehtiniemi |author2=Hanna Nordström |name-list-style=amp |year=2008 |title=Feeding differences among common littoral mysids, Neomysis integer, Praunus flexuosus and P. inermis |journal=Hydrobiologia |volume=614 |issue=1 |pages=309–320 |doi=10.1007/s10750-008-9515-9 }} P. fleuosus is less gregarious than species such as N. integer. When it detects a predator nearby, using a combination of visual and chemical cues, P. flexuosus hides among vegetation.
Life cycle
Praunus flexuosus has two generations per year. A population overwinters, and produces a spring generation that appears in May or June, before dying off in the summer.{{cite journal |author=J. Mauchline |year=1971 |title=The biology of Praunus flexuosus and P. neglectus [Crustacea, Mysidacea] |journal=Journal of the Marine Biological Association of the United Kingdom |volume=51 |issue=3 |pages=641–652 |doi=10.1017/S0025315400015010}} Some of the spring generation reach sexual maturity and reproduce in the autumn, producing the generation which will reproduce the following spring. Females release eggs into a brood pouch or marsupium, where they are held until they hatch.
References
{{Reflist|32em}}
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Category:Crustaceans of the Atlantic Ocean