The orders Amphipoda, Isopoda and Mysida are all members of the class Malacostraca, and are related to crabs and shrimp. While amphipods and mysids are mostly found in marine environments, about half of all isopod species are found on land. Although there is some variation within these orders, amphipods and mysids usually resemble tiny shrimp, while isopods tend to have a similar appearance to land arthropods, such as centipedes and slaters.
