Isopods are generally small crustaceans, usually with seven pairs of legs that range in size from 300 micrometres (Microcerberidae) to nearly 50 centimetres (Bathynomus). Their name, meaning "like-foot" or similar (iso) and foot (pod), probably comes from early zoologists' familiarity with the common terrestrial "slaters" or "woodlice" (other names: cloportes, pissebedden, pillbugs, roly-polies, sowbugs). The isopods are diverse, with 10 425 species found in all ecosystems from the deepest oceans to montane terrestrial habitats as well as deep underground in caves or aquifers. Isopods are thought of as dorsoventrally flattened, as in the typical terrestrial slater, and indeed many species fit this morphological stereotype. Isopods from deep sea and groundwater habitats, and especially parasitic taxa, may depart considerably from this typical body plan.
The isopods belong to the well-known crustacean group, Malacostraca, which includes familiar crustaceans such as shrimp, crabs, lobsters and krill. Unlike those malacostracans with an obvious carapace, isopods lack one. Isopods belong to the superorder Peracarida, which includes a diverse array of taxa that all brood their young in a ventral pouch between their legs. Isopods are unique among these crustaceans for many reasons. Because they lack a carapace, the gills, which are covered by the carapace in other groups, are absent, so they breathe using specialised lamellar gill-like pleopods ("swimming limbs") on the posterior section of the body. In many terrestrial isopods, the pleopods bear respiratory structures similar to lungs. Internally, the heart is positioned in the posterior section of the thorax to provide increased circulation for the gills. Unlike all other crustaceans, the isopods shed their cuticle (a process called ecdysis) in two steps (biphasic molting).
This site has the following aims:

1. to provide a catalogue of the world's isopod species
2. to promote stability in isopod nomenclature
3. to act as a tool for higher taxonomic revisions and regional monographs
4. to provide a base link for other online databases that use isopod nomenclature

To provide sufficient expert knowledge for maintaining the list, we have formed an editorial committee to whom the queries on particular taxa should be addressed.
This list began as an initiative of the US National Museum of Natural History, Smithsonian Institution, maintained by the late Brian Kensley and Marilyn Schotte (now retired). It grew into a valuable resource for providing nomenclature on the Isopoda and was hosted for many years at http://invertebrates.si.edu/isopod/. This list has now been migrated to http://www.marinespecies.org, and updated with more detailed information on synonymies and distributions as well as a capability to host more information, such as images, original literature, and specimen data.