1. a lid-like covering or flap that can open and close
Usage: biology
2. a plate that covers the gills of fish
Usage: biology
3. a horny or calcareous plate that closes the opening of a gastropod shell
Usage: biology

Examples

• The fish’s operculum protects its delicate gills from damage.
• When threatened, the snail retreats into its shell and seals the opening with its operculum.
• The biologist examined the operculum to identify the fish species.
• Each gill chamber is covered by a bony operculum that moves during breathing.
• The operculum acts like a trapdoor for many marine gastropods.
• Students learned to identify the operculum as part of fish anatomy.