Operculum

Definition

The operculum is a protective structure that covers the opening of a mollusc's shell when the animal retracts inside. It acts as a barrier against predators and environmental stress.

5 Must Know Facts For Your Next Test

1. The operculum is commonly found in gastropods like snails.
2. It is often composed of calcium carbonate or proteinaceous material.
3. Opercula can vary in shape and size depending on the species.
4. In some annelids, an operculum can also be present to protect their tube-like structures.
5. The operculum helps prevent desiccation in terrestrial molluscs.

Review Questions

• What is the primary function of an operculum in molluscs?
• Name two materials that can make up an operculum.
• How does the presence of an operculum benefit terrestrial molluscs?

Related terms

Mantle: A significant part of a mollusc's anatomy that secretes the shell and forms a cavity for respiration and excretion.

Radula: A toothed, chitinous ribbon used by molluscs for feeding, often compared to a tongue.

Setae: Bristle-like structures in annelids used for locomotion or sensory purposes.