Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc. Slugs bodies are made up mostly of water and, without a full-sized shell, their soft tissues are prone to desiccation. Slugs produce two types of mucus: thin watery, thick and sticky. The majority of land slugs have two pairs or tentacles on their head. Hygroscopic slime trail. Rock stone going keel foot fringe vestigial shell tail respiratory opening mantle macro close up disgusting abominable nasty detestable cloying loathsome sickening parasitic parasit parasitical large big long giant black brown grey wild life documentary. 4K UHD 3840X2160.