Mysida is an order of small, shrimp-like crustaceans in the malacostracan superorder Peracarida. The shape and complexity corresponds roughly to that of a modern malacostracan brain. There are 170 malacostracan species and six malacostracan subspecies assessed as endangered. There are 307 malacostracan species and 14 malacostracan subspecies assessed as vulnerable. There are 125 malacostracan species and one malacostracan subspecies assessed as critically endangered. There are 1130 malacostracan species and 17 malacostracan subspecies assessed as data deficient. There are 1193 malacostracan species and 15 malacostracan subspecies assessed as least concern.