Snails have well developed shells, which are generally spiral in shape.
As a result, slugs can move through relatively small holes and crevices in soil habitats. The skin of slugs regulates body water content and secretes a covering of slime which protects the animal from desiccation. The foot includes a gland that produces mucus on which the animal crawls. As a result, movement of slugs or snails across a plant or substance is marked by a characteristic trail of mucus which is sometimes referred to as a slime trail. In Ohio, slugs found in the field may be native or of European origin.