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a subclass of Gastropoda, or gastropod mollusks.
Most pulmonates have well-developed shells and lack opercula. The number of known species is 15,000 (according to other data, 35,000); there are more than a thousand species in the USSR. Most are land or freshwater snails (some are marine). They breathe by means of a unique lung—a cavity between the mantle and the body, whose superior wall is threaded with a rich network of blood vessels. In species that live at great depths or in fast-running water, the lung fills with water and the snails breathe the oxygen dissolved in it. Pulmonates are hermaphrodites and develop without a larval stage.
There are two orders. Basommatophora are predominantly freshwater species, with eyes located at the base of the single pair of cephalic antennae (Ancylus, Planorbis, and pond snails). Sty-lommatophora are land species with two pairs of antennae and eyes at the tips of the superior pair (the edible snail—Helix pomatia—and slugs). Many pulmonates are intermediate hosts of parasitic worms that harm domestic and commercial animals. Some are agricultural pests (Achatina and slugs). Some large pulmonates, such as the edible snail, are used as food by humans.
REFERENCESZhadin, V. I. Molliuski presnykh i solonovatykh vod SSSR. Moscow-Leningrad, 1952.
Likharev, I. M., and E. S. Rammel’meier. Nazemnye molliuski fauny SSSR. Moscow-Leningrad, 1952.
I. M. LIKHAREV