The radula is an anatomical structure found in molluscs and used for feeding. It is a minutely toothed, chitinous ribbon. It is typically used for scraping or cutting food before the food enters the esophagus. The radula is unique to the molluscs, and is found in all clades of mollusks except for the bivalves. Within the gastropods, the radula is used in feeding by both herbivorous and carnivorous snails and slugs. The arrangement of teeth on the radula ribbon varies considerably however from one group to another.