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 | |
|---|---|
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| Species: | P. flexuosus |
| Binomial name | |
| Praunus flexuosus (O. F. Müller, 1776) | |
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]
| Character | P. flexuosus | P. neglectus |
|---|---|---|
| Body length | 25–26 mm (1.0 in) | 20 mm (0.8 in) |
| 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, 1⁄6 of telson length | proximally 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]
References
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