Biodiversity & Conservation

An opossum shrimp - Neomysis integer

Neomysis integer

Image Marco Faasse - Neomysis integer.
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Distribution map

Neomysis integer recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

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Neomysis integer is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Arthropoda Arthropods, joint-legged animals, e.g. insects, crustaceans & spiders
Class Malacostraca Crabs, lobsters, sand hoppers and sea slaters
Authority (Leach, 1814)
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland Records indicate Neomysis integer to have a widespread, but patchy distribution on all British and Irish coasts in locations of lowered salinity, usually estuaries or brackish water enclosures.
Habitat information icon Habitat information Neomysis integer is the dominant mysid shrimp in the upper reaches of estuaries. It is also found in non-tidal lagoons, isolated bodies of nearly freshwater, and in high shore hypersaline pools, but is rare in fully marine habitats.
Text page icon Description A slender, free-swimming, shrimp that grows up to 17 mm in length. Its body is almost transparent, with occasional brown pigmentation. The species has a well developed carapace, which protects the large stalked eyes, head and thorax. The rostrum of the head is distinctly pointed but short. Its antennae are conspicuous and biramous (having an inner and outer extension), the outer extension (exopod) of the second pair of antennae, takes the form of a flattened plate, known as the antennal scale. The antennal scale is bordered along its margin with setae and is an important diagnostic characteristic. Thoracic limbs are well developed and also biramous, the outer set have a distinctly feathery appearance. Abdominal limbs are less developed and finger-like, with the exception of the last pair which are biramous and flattened, and form the tail fan (uropods).
Identifying features
  • Body almost transparent; up to 17 mm in length.
  • Large eyes on stalks.
  • Well developed carapace with distinctly pointed but short rostrum.
  • Two pairs of conspicuous antennae, both biramous.
  • First pair of antennae are long. Outer limb of second antenna, forms antennal scale, which is very long and narrow, tapering to a point.
  • Thoracic appendages all biramous, the outer limbs (exopods) are fringed (appear feather like).
  • Abdominal appendages (pleopods) also biramous. Male pleopods are small, the 4th pair are elongated with a terminal pair of barbed setae.
  • The telson (tail blade) is long, triangular in outline with narrow truncated tip; short spines around margin.
Additional information icon Additional information The species seems to be particularly susceptible to injury, causing atypical morphology which may lead to misidentification (Hayward & Ryland, 1995). Synonyms of Mysis or Neomysis vulgaris were in use in the early and continental literature, though Tattersall & Tattersall (1951) considered the specific integer (Leach) to have priority (Parker, 1979).

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This review can be cited as follows:

Georgina Budd 2008. Neomysis integer. An opossum shrimp. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 09/02/2010]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=3884>