How are the gills of fish protected?

- Operculum: The operculum is a flap of skin and bone that covers and protects the gills. It is made up of four bones: the opercle, the subopercle, the interopercle, and the preopercle. The operculum opens and closes to allow water to flow over the gills.

- Gill rakers: Gill rakers are small, bony projections that line the gill arches. They help to filter out debris from the water and protect the delicate gill filaments.

- Gill filaments: Gill filaments are the thin, feathery structures that contain the blood vessels that exchange oxygen and carbon dioxide with the water. They are protected by a thin layer of mucus.

- Mucus: Mucus is a slimy substance that is secreted by the gills. It helps to lubricate the gills and protect them from damage.

These mechanisms work together to protect the gills of fish from damage and to allow them to function efficiently.