Which structure in a mollusk is primarily used for feeding?

The radula is a distinctive feeding structure found in many mollusks, particularly those in the class Gastropoda, such as snails and slugs. It functions like a raspy tongue, equipped with numerous tiny teeth that allow the organism to scrape or cut food before ingestion. This allows mollusks to feed on a variety of materials, including algae, plant matter, and even other small organisms, depending on their dietary habits. The presence of the radula is crucial for their feeding efficiency, enabling them to adapt to different environments and food sources.

In contrast, the foot is primarily used for locomotion, and while the shell offers protection and support, it does not assist in feeding. The velum, found in some mollusks like bivalves, is typically involved in locomotion or feeding through filter-feeding mechanisms rather than direct scraping or cutting of food. Therefore, the radula clearly serves as the primary structure for feeding in many mollusks, making it the correct choice.