Operculum (fish)


Operculum (fish)
Campanologies hectoris
1. operculum (gill cover), 2. lateral line, 3. dorsal fin, 4. adipose fin, 5. caudal peduncle, 6. caudal fin, 7. anal fin, 8. photophores, 9. pelvic fins (paired), 10. pectoral fins (paired)

The operculum of a bony fish is the hard bony flap covering and protecting the gills. In most fish, the rear edge of the operculum roughly marks the division between the head and the body.

The operculum is composed of four fused bones; the opercle, preopercle, interopercle, and subopercle. These appear to be derived from the separate gill-slit covers of an elasmobranch ancestor of the teleost fishes. The posterior rim of the operculum is equipped with a flexible, ribbed structure which acts as a seal to prevent reverse water flow during respiration. The morphology of this anatomical feature varies greatly between species. For example, the bluegill (Lepomis macrochirus) has a posteriorly and dorsally oriented rounded extension with a small black splotch present. In some species, the operculum can push water from the buccal cavity through the gills.

For some fish, opercula are vital in obtaining oxygen. They open as the mouth closes, causing the pressure inside the fish to drop. Water then flows towards the lower pressure across the fish's gill lamellae, allowing some oxygen to be absorbed from the water.

Whereas the cartilaginous ratfishes have soft and flexible opercular flaps, the sharks, rays and relatives (elasmobranch fishes) lack opercula completely and respire instead through a series of gill slits perforating the body wall. Without opercula, other methods of getting water to the gills are required, such as ventilation.

See also

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Operculum — may refer to: Operculum (animal), a stiff structure resembling a lid or a small door that opens and closes Operculum (gastropod), a lid on the shell of some gastropods Operculum (bryozoa), a lid on the orifice of some bryozoans Operculum (fish),… …   Wikipedia

  • Operculum (animal) — A live individual of the sea snail Rapana venosa retracted into the shell, with the operculum closing the aperture …   Wikipedia

  • Fish — /fish/, n. Hamilton, 1808 93, U.S. statesman: secretary of state 1869 77. * * * I Any of more than 24,000 species of cold blooded vertebrates found worldwide in fresh and salt water. Living species range from the primitive lampreys and hagfishes… …   Universalium

  • Fish — are aquatic vertebrate animals that are typically ectothermic (previously cold blooded), covered with scales, and equipped with two sets of paired fins and several unpaired fins. Fish are abundant in the sea and in fresh water, with species being …   Wikipedia

  • operculum — ► NOUN (pl. opercula) Zoology 1) a flap of skin protecting a fish s gills, typically stiffened by bony plates. 2) a plate that closes the aperture of a gastropod mollusc s shell. ORIGIN Latin, lid, covering …   English terms dictionary

  • operculum — [ō pʉr′kyo͞o ləm, ō pʉr′kyələm] n. pl. opercula [ō pʉr′kyo͞olə, ō pʉr′kyələ] or operculums [ModL < L, lid, dim. < operire, to close, shut: for IE bases see OB & APERTURE] any of various covering flaps or lidlike structures in plants and… …   English World dictionary

  • fish — fishless, adj. /fish/, n., pl. (esp. collectively) fish, (esp. referring to two or more kinds or species) fishes, v. n. 1. any of various cold blooded, aquatic vertebrates, having gills, commonly fins, and typically an elongated body covered with …   Universalium

  • Fish anatomy — The anatomy of fish is primarily governed by the physical characteristics of water, which is much denser than air, holds a relatively small amount of dissolved oxygen, and absorbs light more than air does. Body (1) operculum (gill cover), (2)… …   Wikipedia

  • Fish migration — Many species of salmon are anadromous and migrate long distances up rivers and streams to spawn. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres… …   Wikipedia

  • Fish locomotion — The prevailing type of fish locomotion is swimming in water. In addition, some fish can walk , i.e., move over land, burrow in mud, and glide through the air. Contents 1 Swimming 1.1 Body/caudal fin propulsion 1.1.1 Anguilliform locomotion …   Wikipedia