Operculum (fish)

The gill cover ( operculum ) is a bony covering of the gill area in bony fish ( Osteichthyes ).

The operculum consists of three bones: Operculare, Suboperculare and Interoperculare. The Praeoperculare, as the name says, "before the operculum" located belongs functionally to this and instead provides the abutment or hinge whose movements Represents the rear abutment is the shoulder girdle.

Due to the spreading of the gill cover and the lowering of the floor of the mouth, the volume of the gill area enlarged. Due to the resulting vacuum is drawn through the same open mouth water. The gill openings are sealed off by the gill membranes. Join the gill cover and raises the floor of the mouth, then the gill chamber and the respiratory water is reduced to the oxygen -absorbing gills past ejected through the gill slits. However, since the oral cavity and the paired gill cavity expand a little time lag and narrow, an almost continuous stream of water may result ( in countercurrent to the blood flow ) through the gills. The gill lamellae depend not passive in the water flow, but themselves act as ( non-return ) valves.

Operculum Similar skin flaps are already present in the cartilaginous fish belonging to the chimaeras, sharks and rays, however, lacks an outer gill cavity. When Acanthodier Climatius each gill slit had a small cover at the more advanced Acanthodiern how acanthodes there was a common cover for all gill arches. The operculum can be subsequently reduced again, such as the moray eels, puffer fish ( Tetraodontidae ) and sunfish ( Molidae ). In these cases the floor of the mouth assumes its pumping function.