Mysidacea is an order of the class Malacostraca from the subphylum Crustacea. They are small, pelagic living, shrimp-like crustaceans. The carapace is not fused with the last four thoracic segments but covers them loosely. they have a visible statocyst in the uropod endopodite. The first one or two pairs of thoracic appendages are maxillipeds, the other six or seven are uniform and filamentous. They live near the seabed in large swarms, and form an important food source for fish.

Alternative form for mysid : mysids.