• Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Crustacea
  • Class: Malacostraca
  • Subclass: Eumalacostraca
  • Superorder: Peracarida
  • Order: Mysida
  • Norwegian: pungreker


Opossum shrimps, also called mysid shrimps, (order Mysida) are small shrimp-like crustaceans with a body length from 5 to 30 mm. They are free-swimming or resting on the bottom or on algae. In contrast to the larger shrimps and other decapods, they have eight pair of legs rather then five. The shell is soft and flexible. Many species are translucent and almost invisible in normal daylight.


The order Mysida belongs to the superorder Peracarida, which means "near-to-shrimps". You will also find amphipods and isopods in the same superorder. Only five families of marine mysid shrimps are registered. MarBEF - The European Register of Marine Species, includes only two families, Mysidae and Petalophthalmidae.