They are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, and from small seeps and springs to major rivers.
Freshwater snails are indirectly among the deadliest animals to humans, as they carry parasitic worms that cause schistosomiasis, a disease estimated to kill between 10,000 and 200,000 people annually.
† Paleozoic molluscs of uncertain systematic position † Basal taxa that are certainly Gastropoda Patellogastropoda Vetigastropoda Cocculiniformia † Paleozoic Neritimorpha of uncertain systematic position † Cyrtoneritimorpha Cycloneritimorpha: Neritiliidae and Neritidae Caenogastropoda of uncertain systematic position Architaenioglossa: Ampullariidae and Viviparidae Sorbeoconcha: Melanopsidae, Pachychilidae, Paludomidae, Pleuroceridae, Semisulcospiridae and Thiaridae Littorinimorpha: Littorinidae, Amnicolidae, Assimineidae, Bithyniidae, Cochliopidae, Helicostoidae, Hydrobiidae, Lithoglyphidae, Moitessieriidae, Pomatiopsidae and Stenothyridae Ptenoglossa Neogastropoda: Nassariidae and Marginellidae Lower Heterobranchia: Valvatidae Nudipleura Euopisthobranchia Glacidorboidea with the only family Glacidorbidae Hygrophila: Chilinidae, Latiidae, Acroloxidae, Lymnaeidae.
Planorbidae ► and Physidae Acochlidiacea: Acochlidiidae, Tantulidae and Strubelliidae Eupulmonata The Neritimorpha are a group of primitive "prosobranch" gilled snails which have a shelly operculum.
On the basis of their findings, Noel et al.[12] concluded that both outbred and inbred populations of P. acuta can efficiently eliminate deleterious mutations.
Archaeological investigations in Guatemala have revealed that the diet of the Maya of the Classic Period (AD 250–900) included freshwater snails.
[15] Basommatophoran snails are even more widely infected, with many Biomphalaria (Planorbidae) serving as hosts for Schistosoma mansoni, Fasciolopsis and other parasitic groups.
[14] The term "neglected tropical diseases" applies to all snail-borne infections, including schistosomiasis, fascioliasis, fasciolopsiasis, paragonimiasis, opisthorchiasis, clonorchiasis, and angiostrongyliasis.