noun, plural o·per·cu·la [oh-pur-kyuh-luh] /oʊˈpɜr kyə lə/, o·per·cu·lums.
- the gill cover of fishes and amphibians.
- (in many gastropods) a horny plate that closes the opening of the shell when the animal is retracted.
Origin of operculum
Related formso·per·cu·lar, adjective
Examples from the Web for operculum
Clitia is known from Creusia, by the articulations of the valves, and by the operculum, which in Creusia consists of four valves.A Conchological Manual|George Brettingham Sowerby
Behind the hyomandibular there is a large bony plate, the operculum, formed of four large membrane bones.The Vertebrate Skeleton|Sidney H. Reynolds
Shell fusiform and solid, aperture elongated, columella folded; no operculum; eyes on sides of tentacles.
The operculum is calcareous, with eccentric, deeply cut grooves.The Sea-beach at Ebb-tide|Augusta Foote Arnold
The shell consists of six plates, with an operculum of four valves.
British Dictionary definitions for operculum
noun plural -la (-lə) or -lums
- the hard bony flap covering the gill slits in fishes
- the bony plate in certain gastropods covering the opening of the shell when the body is withdrawn