The Syncarida includes 200 described species divided between two orders, the Anaspidacea and the Bathynellacea. Bathynellaceans occur worldwide in interstitial (spaces between sand grains) or groundwater habitats, whereas the anaspididaceans are strictly Gondwanan
in their distribution (i.e., limited to the southern continents). Many anaspididaceans are apparently endemic (limited to) to Tasmania
, where they are found in freshwater habitats such as open lake surfaces, streams, ponds, and crayfish burrows. No syncarids are marine. Anaspididaceans are mostly less than 1 cm long, although some may reach 5 cm; bathynellaceans range from 1 to 3 mm in length. Syncarids move by either crawling or swimming. Little is known about the biology of most species, but some are considered to be omnivorous. Unlike most other crustaceans, which carry their eggs and early developing embryos, syncarids deposit their eggs on a substrate or shed them into the water following copulation. (Brusca and Brusca 2003) Camacho (2006) provides an annotated list of the 256 species and subspecies of Syncarida then known, including synonymies, information on habitat type ( caves, springs, wells, etc.), type locality, other localities where each taxon has been found, and an abbreviated reference to the original description and other important taxonomic references when available. Critical remarks about the validity of some taxa are also included. A summary of genera and species known per continent and a map of the world distribution of genera is presented, as well as a comprehensive list of syncarid literature.