Gill cover

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

The bones of the Opercular series in a perch : Operculare (yellow), Praeoperculare (red), Interoperculare (green) and Suboperculare (pink). The preopercular is not an element of the actual gill cover of the bony fish.

The gill cover consists of three individual bones: operculare , suboperculare and interoperculare . The preopercular , as the name suggests, "located in front of the gill cover" does not functionally belong to this, but represents the abutment or hinge of its movements. The rear abutment is the shoulder girdle .

By spreading the gill cover and lowering the floor of the mouth, the volume of the gill space increases. The resulting negative pressure sucks in water through the open mouth. The gill slits are sealed by the gill membranes. If the gill covers close and the floor of the mouth rises, the gill space is reduced and the respiratory water is expelled past the oxygen-absorbing gills through the gill slits. But since the oral cavity and the paired gill cavity expand and constrict somewhat delayed, an almost constant flow of water (in countercurrent to the flow of blood) can pull over the gills. The gill leaves do not hang passively in the water flow, but act as (non- return ) valves themselves .

Gill cap-like skin flaps are already present in the sea ​​cats belonging to the cartilaginous fish , while sharks and rays lack an outer gill cavity. In the Acanthodier Climatius , each individual cleft gill had a small lid, in the more advanced Acanthodians, such as Acanthodes , there was a common lid for all gill arches. The gill cover can also be reduced again afterwards, for example in moray eels , puffer fish (Tetraodontidae) and sunfish (Molidae). In these cases the floor of the mouth takes over its pumping function.

literature

• Kurt Fiedler: Textbook of Special Zoology, Volume II, Part 2: Fish . Gustav Fischer Verlag, Jena 1991, ISBN 3-334-00339-6 .

Individual evidence

1. ↑ Juraj Holcik: The Freshwater Fishes of Europe, 9 Vols., Vol. 1/2: General Introduction to Fishes, Acipenseridae. Pp. 29-30, Aula-Verlag, Wiesbaden 1989, ISBN 3-891-04431-3 .
2. ↑ Fishbase Glossary: Operculum ( Memento of the original from January 25, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
3. ^ Fiedler, p. 148
4. ↑ Fiedler, p. 54
5. ↑ Fiedler, p. 245