The Mysidacea is a group of

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

-like

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

s in the superorder Peracarida, comprising the two extant

orders Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Mysida and

Lophogastrida Lophogastrida is an order of malacostracan crustaceans in the superorder Peracarida, comprising shrimp-like animals that mostly inhabit the relatively deep pelagic waters of the oceans throughout the world. Most lophogastridan species are long, ...

and the prehistoric

Pygocephalomorpha The order Pygocephalomorpha is an extinct group of peracarid crustaceans. Pygocephalomorpha were abundant from the Carboniferous until their extinction in the Permian. Families The order contains extinct five families, and seven genera ''incert ...

. Current data indicate that despite their external similarities, the three orders are not closely related, and the taxon Mysidacea is not used in modern taxonomy.

References

{{Taxonbar, from=Q1208947 Malacostraca Obsolete arthropod taxa