There are no extant marine fairy shrimps, but some species may occur in mountain lakes with almost pure water, while others—mainly Artemia—occur in saturated brine. In the Artemiina, the distribution of Artemia and Parartemia species used to be complementary. Artemia occurred in bodies of salt water on all continents except Australia, and Parartemia only in Australia. In the twentieth century, however, several species of Artemia were successfully introduced in various parts of Australia.

Most families of anostracans are found on three or four continents, but their ranges are often restricted to parts of a continent at the subfamily or genus level. For example, in the Thamnocephalidae, the genus Thamnocephalus is restricted to North America and northern South America, while Dendro-cephalus is found exclusively in South America. A peculiar type of disjunct (widely separated) distribution is seen in the genus Branchipodopsis, which is represented in southern Africa by more than 15 species. Elsewhere in Africa, however, it has been reliably recorded only on the horn of Africa and the island of Socotra. The genus also occurs in such widely separated locations as Oman, the Caspian basin, and the Mongolian plateau. At the species (and sometimes genus) level, ranges may be extremely small, often restricted to the type locality. Such is the case with several species of Californian Branchinecta. Other species with extremely small ranges are found further south in Baja California. Another example is the genus Dexteria, limited to the area around Gainesville, Florida, and probably extinct by now as a result of the city's development.

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