Lymnaeoidea

Lymnaeoidea is a taxonomic superfamily of freshwater pulmonate gastropods within the class Gastropoda. It comprises several families, most notably Lymnaeidae, commonly known as pond snails, and includes related genera that together define the group. The superfamily has a worldwide distribution, with species inhabiting a range of freshwater habitats such as ponds, lakes, marshes, and slow-moving rivers.

Members typically have small to medium-sized shells that are elongate or conical, with a relatively long aperture and well-defined whorls. They are aquatic, air-breathing snails that rely on a lung-like pallial cavity rather than gills. Their feeding habits are primarily detritivorous and herbivorous, grazing on periphytic algae, decaying vegetation, and associated matter.

Ecologically, Lymnaeidae and allied families play important roles as grazers in freshwater ecosystems. They are also notable from a health perspective because several lymnaeid species act as intermediate hosts in parasite life cycles; Fasciola hepatica, the liver fluke, is a prominent example of a parasite that uses some Lymnaea species during its lifecycle.

Taxonomic boundaries within Lymnaeoidea have shifted with advances in molecular phylogenetics, and the exact composition of the group varies among authorities. The best-known genus within the group is Lymnaea, which includes widely studied species such as Lymnaea stagnalis. Other lymnaeid genera include Radix and Austropeplea. The group is characterized by its cosmopolitan distribution and adaptation to a broad range of freshwater environments.