Praunus flexuosus

Praunus flexuosus, known as the chameleon shrimp, is a species of opossum shrimp found in European waters. It reaches 26 mm (1.0 in) 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.

Praunus flexuosus
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Subphylum:
Crustacea
Class:
Malacostraca
Order:
Mysida
Family:
Mysidae
Genus:
Praunus
Species:
P. flexuosus
Binomial name
Praunus flexuosus

Description

Praunus flexuosus is a long, slender animal, with a pronounced bend in the abdomen.[1] It reaches sexual maturity at a length of around 18 millimetres (0.71 in), but can go on to attain a length of 26 mm (1.0 in).[1] Its colouration is highly variable, ranging from brown or red to green, which accounts for its common name of "chamaeleon shrimp".[2]

Praunus flexuosus is very similar to the related species P. neglectus. The two can be differentiated by the following characters:[1]

CharacterP. flexuosusP. neglectus
Body length25–26 mm (1.0 in)20 mm (0.8 in)
Colourblack to colourlessusually grass green
Setae on antennal scale and uropodscolourlessviolet or reddish purple
Antennal scale length>3× peduncle<3× peduncle
Antennal scale shape7–8× as long as broad5× as long as broad
Apex of antennal scaleshorter than spine terminating outer marginlonger than spine terminating outer margin
Tarsus of thoracic limbs 3–76 segmented5 segmented
Tarsus of thoracic limb 85 segmented4 segmented
Lateral margins of telson21–27 small spines18–20 larger spines
Cleft in telsonwidely open, ​1⁄6 of telson lengthproximally narrow, ​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.[3]

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.[1] There is only one doubtful record from further south than Roscoff.[1] It is "the only documented non-native marine zooplankton species established on the East Coast [of North America]".[4] It was first discovered in North America in 1960, on the north side of Cape Cod,[5] and has since colonised as far north as Nova Scotia.[6] This colonisation may have occurred after P. flexuosus was transported as a fouling animal on ships' hulls during the Second World War.[7] It was only discovered around the coast of Iceland in 1970, but has since proved to be common along Iceland's south-west coast.[7] This introduction may also have been facilitated by wartime convoys (see Battle of the Atlantic).[7]

P. flexuosus can tolerate salinities of 2‰–33‰.[8] It is often found on algae, and is most closely associated with the seaweed Fucus vesiculosus.[9] It lives in shallow water, and is often found around artificial constructions, such as docks.[10] It is an omnivore, feeding on debris and preying on small crustaceans, especially harpacticoid copepods,[11] but consumes a greater proportion of macrozooplankton than other common littoral mysids, such as Neomysis integer and Praunus inermis.[12] P. fleuosus is less gregarious than species such as N. integer.[9] When it detects a predator nearby, using a combination of visual and chemical cues, P. flexuosus hides among vegetation.[9]

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.[11] Some of the spring generation reach sexual maturity and reproduce in the autumn, producing the generation which will reproduce the following spring.[11] Females release eggs into a brood pouch or marsupium, where they are held until they hatch.[11]

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References
  1. Mario de Kluijver; Sarita Ingalsuo (eds.). "Praunus flexuosus". Macrobenthos of the North Sea – Crustacea. Retrieved July 20, 2011.
  2. Nellie Barbara Eales (1967). Littoral Fauna of the British Isles. Cambridge University Press. ISBN 978-0-521-04862-0.
  3. Karl J. Wittmann (1999). "Global biodiversity in Mysidacea, with notes on the effects of human impact". In Frederick R. Schram & J. C. von Vaupel Klein (ed.). Crustaceans and the Biodiversity Crisis: Proceedings of the Fourth International Crustacean Congress, Amsterdam, the Netherlands, July 20–24, 1998. Crustacean Issues. 12. Brill. pp. 511–525. ISBN 978-90-04-11387-9.
  4. Gregory Ruiz; Paul Fofonoff; Brian Steves; Alisha Dalhstrom (2011). "Marine crustacean invasions in North America: a synthesis of historical records and documented impacts". In Bella S. Galil; Paul F. Clark; James T. Carlton (eds.). In the Wrong Place – Alien Marine Crustaceans: Distribution, Biology and Impacts. Invading Nature. 6. Springer. pp. 215–250. ISBN 978-94-007-0590-6.
  5. Roland L. Wigley (1963). "Occurrence of Praunus flexuosus (O. F. Müller) (Mysidacea) in New England waters". Crustaceana. 6 (2): 158. doi:10.1163/156854063X00534.
  6. Kenneth L. Gosner (1999). "Mysid shrimps". A Field Guide to the Atlantic Seashore: From the Bay of Fundy to Cape Hatteras. Peterson Field Guide. 24. Houghton Mifflin Harcourt. pp. 229–230. ISBN 978-0-618-00209-2.
  7. Olafur S. Astthorsson (1987). "Records and life history of Praunus flexuosus (Crustacea: Mysidacea) in Icelandic waters". Journal of Plankton Research. 9 (5): 955–964. doi:10.1093/plankt/9.5.955.
  8. D. S. McClusky & V. E. J. Heard (1971). "Some effects of salinity on the mysid Praunus flexuosus". Journal of the Marine Biological Association of the United Kingdom. 51 (3): 709–715. doi:10.1017/S0025315400015083.
  9. E. Lindén; M. Lehtiniemi & M. Viitasalo (2003). "Predator avoidance behaviour of Baltic littoral mysids Neomysis integer and Praunus flexuosus" (PDF). Marine Biology. 143: 845–850. doi:10.1007/s00227-003-1149-x.
  10. P. J. Hayward; M. J. Isaac; P. Makings; J. Moyse; E. Naylor; G. Smaldon (1995). "Crustaceans". In P. J. Hayward & John Stanley Ryland (ed.). Handbook of the Marine Fauna of North-west Europe. Oxford University Press. pp. 289–461. ISBN 978-0-19-854055-7.
  11. J. Mauchline (1971). "The biology of Praunus flexuosus and P. neglectus [Crustacea, Mysidacea]". Journal of the Marine Biological Association of the United Kingdom. 51 (3): 641–652. doi:10.1017/S0025315400015010.
  12. Maiju Lehtiniemi & Hanna Nordström (2008). "Feeding differences among common littoral mysids, Neomysis integer, Praunus flexuosus and P. inermis". Hydrobiologia. 614 (1): 309–320. doi:10.1007/s10750-008-9515-9.
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