Slugs have teeth that number in the thousands. The rows of backward-pointing, replaceable teeth are attached to the slug's radula in an arrangement known as denticles. The radula is a ribbon-like structure that holds the teeth.
Herbivorous slugs use the radula to feed by grazing or scraping food off of various surfaces, while carnivorous slugs, such as the ghost slug, have elongated teeth located on the radula that they use to seize and devour earthworms. Some species of slugs also use the radula for combat. The radula is typically made up of rows of bilaterally symmetrical self-similar teeth that are generally rooted inside the membrane of the radula. In some species of slugs, the teeth bend with the membrane as it moves, while the teeth move as one complete entity in other species.