gastropod

Gastropoda, commonly called gastropods, is a large and diverse class of mollusks that includes snails and slugs. They occupy almost every habitat from deep ocean floors to deserts and freshwater bodies. They are the largest group within the phylum Mollusca, with tens of thousands of living species.

A distinctive feature is torsion, a 180-degree twisting of the visceral mass that occurs during larval development, producing an asymmetrical body plan. Most gastropods move using a broad muscular foot. The head bears sensory tentacles and eyes. Feeding is typically by a radula, a toothed belt used to scrape or cut food.

Many have a snail-like shell secreted by the mantle; shells are usually coiled and protective, though slugs have a reduced or absent shell. Shell morphology and life habits vary; some are marine, others freshwater or terrestrial.

Ecology and reproduction: Diet ranges from algae and plants to detritus and even other animals. Reproduction strategies vary; many land snails are hermaphroditic with internal fertilization, while some species have separate sexes. Development may be direct or involve free-swimming veliger larvae in marine species.

Economical and ecological importance: They serve as food sources for humans and wildlife; some are pests in agriculture; several groups are important for studies of evolution and molluscan biology. Conservation concerns include habitat loss and invasive species in some regions.