Isopoda is an order (group) of crustaceans that includes woodlice, sea slaters and their relatives.
Copepods from Ernst Haeckel 's Kunstformen der Natur. Copepods form a subclass belonging to the subphylum Crustacea (crustaceans); they are divided into ten orders. Some 13,000 species of copepods are known, and 2,800 of them live in fresh water. Most copepods have a single compound eye in the middle of their head, but copepods of the genus Corycaeus possess two large cuticular lenses paired to form a telescope. Copepods vary considerably, but can typically be 1 to 2 mm (0.04 to 0.08 in) long, with a teardrop-shaped body and large antennae. Crustaceans belong to the phylum Arthropoda, along with insects, arachnids, millipedes, centipedes, and fossil trilobites. However, crustaceans occupy their own subphylum, Crustacea. The term crustacean derives from the Latin crusta, meaning crust or hard shell. A small number of crustaceans live on land. Whether marine or terrestrial, crustaceans share certain traits that determine their inclusion in the subphylum Crustacea. As with any large group of organisms, exceptions to these rules will occasionally apply. Most of the 44,000 species of crustaceans live in saltwater or freshwater. A small number of crustaceans live on land. Whether marine or terrestrial, crustaceans share certain traits that determine their inclusion in the subphylum Crustacea. As with any large group of organisms, exceptions to these rules will occasionally apply. Some species are able to roll themselves into a ball to conserve moisture or as a defence mechanism. There are over 10,000 species of isopod worldwide with around 4,500 species found in marine environments, mostly on the seabed, 500 species in fresh water and another 5,000 species on land. The order is divided into eleven suborders. The majority of crustaceans are aquatic and the isopods are one of the few groups of which some members now live on land. The only other crustaceans which include a small number of terrestrial species are amphipods (like sandhoppers) and decapods (crabs, shrimp, etc.). Isopoda is an order (group) of crustaceans that includes woodlice, sea slaters and their relatives. Isopods live in the sea, in fresh water, or on land, and most are small greyish or whitish animals with rigid, segmented exoskeletons (external skeletons). The majority of crustaceans are aquatic and the isopods are one of the few groups of which some members now live on land. The only other crustaceans which include a small number of terrestrial species are amphipods (like sandhoppers) and decapods (crabs, shrimp, etc.). Phylum Arthropoda, Subphylum Crustacea Crustaceans are specialized for life in the water Most possess gills to obtain oxygen Chitinous exoskeleton reinforced with CaCO3 Two pairs of antennae Barnacles are crustaceans! The wonderful world of crustaceans! The majority of marine arthropods are crustaceans (subphylum Crustacea). Crustaceans are distinguished from other Arthropods by their possession of a pair of biramous (two-parted) limbs, and by a nauplius larval stage. Includes barnacles, shrimp, krill, crabs, lobsters, and copepods. SPHAEROMATIDAE and other isopods. The Isopoda are small crustaceans with seven pairs of legs that range in size from 300 micrometres (Microcerberidae) to nearly 50 centimetres (Bathynomus). Subphylum Crustacea, Crustaceans. Pillbugs are crustaceans, more closely related to shrimp and crabs than to insects. Photo Credit: Photo: Joseph Berger, Bugwood.org. Sources: Borror and DeLong’s Introduction to the Study of Insects, 7th edition, byCharles A. Triplehorn and Norman F. Johnson. A small number of crustaceans live on land. Whether marine or terrestrial, crustaceans share certain traits that determine their inclusion in the subphylum Crustacea. As with any large group of organisms, exceptions to these rules will occasionally apply. Pillbugs, also known as sowbugs, or woodlice, are familiar backyard creepy crawlies to most of us. Pillbugs are correctly. classified as terrestrial Isopods, and belong to the Class Crustacea. Familiar crustaceans include lobsters, crabs, shrimp, and daphnia (water fleas). The crustaceans, in turn, are part of a larger group, Arthropoda, or jointed-legged animals. 
https://en.wikipedia.org/wiki/Copepod http://insects.about.com/od/isopods/ss/Subphylum-Crustacea-Crustaceans.htm http://insects.about.com/od/isopods/ss/Subphylum-Crustacea-Crustaceans.htm https://en.wikipedia.org/wiki/Isopoda https://en.wikipedia.org/wiki/Isopoda http://www2.sunysuffolk.edu/mcnamam/Phylum%20Arthropoda_Subphylum%20Crustacea.ppt http://www.marinespecies.org/isopoda/ http://insects.about.com/od/isopods/ss/Subphylum-Crustacea-Crustaceans.htm http://www3.northern.edu/natsource/INVERT1/Pillbu1.htm
what subphylum do isopods belong to