Apple snails are freshwater (some amphibious) snails that are distributed throughout the humid tropics and subtropics of Africa, South and Central America, the Caribbean, southeastern North America, and southern Asia, where they often constitute a major portion of the native freshwater molluscan fauna. They are often referred to as apple snails because of their large, round, frequently greenish shells. The family belongs to the Caenogastropoda, the largest and most diverse group of gastropods (ca. 60% of the living Gastropoda).
The Ampullariidae have a primarily circumtropical distribution, reaching their highest diversity in South America. There are records of ampullariids from the Lower Cretaceous, ~145 million years before present (mybp), and the Upper Jurassic, ~160 mybp, in Africa and Asia respectively, and their fossil record dates back at least 50 mybp in the Neotropics. More than 150 nominal species are recognized in nine extant genera: Afropomus Pilsbry and Bequaert, 1927, Saulea Gray, 1867, and Lanistes Montfort, 1810 are African, Pila Röding, 1798 is African and Asian, Asolene d’Orbigny, 1838, Felipponea Dall, 1919, Marisa Gray, 1824, and Pomella Gray, 1847 are South American, Pomacea Perry, 1810 ranges from Argentina to the southeastern U.S.A. and the Caribbean.