Slug

Slug, terrestrial gastropod mollusk, related to the snail, but with the shell represented by an internal horny plate overlying the respiratory cavity. Slugs are vegetation eaters and often ascend trees in search of food, then let themselves down by means of a mucous thread spun from a gland opening on the anterior edge of the foot. They may do extensive damage to cultivated plants and are particularly damaging in greenhouses and truck farms. The great gray slug, sometimes 10 cm (4 in) long, is a European species, introduced into and now common in eastern North America. A native American slug common in the United States is a small species, less than 2.5 cm (less than 1 in) long. See Gastropod; Mollusk.

Scientific classification: Slugs belong to the class Gastropoda. The native American slug common in the United States belongs to the family Limacidae and is classified as Limax campestris.