Lunged Aquatic Snails (Pulmonates)
Most people know a snail when they see one, but it is less common to be able to tell the difference between the two main types of aquatic snails. Instead of breathing underwater through gills, pulmonate snails breathe via a lunglike pulmonary cavity located within the mantle (the mantle is the part connecting the muscular foot and the head to the shell, and it secretes the material that forms the shell). Many pulmonate snails crawl to the water surface to take in air, but others can stay underwater all the time. Another characteristic of pulmonate snails is that they lack an operculum, a hard horny “trapdoor” that other types of aquatic snails have that closes when the animal retracts into the shell.