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a family of gastropods. The shell, which is spirally coiled and relatively high (in the common freshwater snail, up to 7 cm), usually has a large opening. The eyes are located at the base of the tentacles. The organ of respiration is a lung, which in some species fills with water and functions as a gill. Lymnaeidae are hermaphrodites. Fertilized ova are deposited in the form of mucoid ribbons.
Lymnaeids feed on algae, animals, plant remains, and the tissues of higher plants. They usually inhabit fresh waters and are only rarely encountered in saltwater lakes and the coastal zones of brackish inland seas (for example, the Baltic Sea). There are about 120 species of lymnaeids. The USSR has more than 30 species, united in eight or nine subgenera of the genus Lymnaea. (The subgenera are often considered separate genera.) Almost all lymnaeids are intermediate hosts of worms that are parasites of man and of domestic and wild animals. For example, Lymnaea truncatula transmits the causative agents of fascioliasis of cattle.