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Opercular series in bony fish: operculum (yellow), preoperculum (red), interoperculum (green) and suboperculum (pink) The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills ; it is also used for respiration and feeding.
After the appearance of jawed fish (placoderms, acanthodians, sharks, etc.) about 420 million years ago, most ostracoderm species underwent a decline, and the last ostracoderms became extinct at the end of the Devonian period. More recent research indicates that fish with jaws had far less to do with the extinction of the ostracoderms than ...
The operculum lies on the top rear part of the foot. When the foot is retracted, the operculum is rotated 180° and closes the shell. [2] An operculum (fish), a flap that covers the gills in bony fishes and chimaeras. The cover that rapidly opens a cnida of a cnidarian such as a jellyfish or a sea anemone. The lid may be a single hinged flap or ...
Turbinidae have a strong, thick calcareous operculum readily distinguishing them from the somewhat similar Trochidae or top snails, which have a corneous operculum. This strong operculum serves as a passive defensive structure against predators that try to enter by way of the aperture or that would break the shell at the outer lip.
The large bone which forms the upper posterior part of the operculum. operculum The bony flap that covers the gills. opercular Pertaining to the operculum. opercular spine A spine projecting from the operculum. orbit The eye socket. origin The most anterior point of a fin base. osseous Bony. ovate Egg-shaped.
In modern fishes, the cleithrum is a large bone that extends upwards from the base of the pectoral fin and anchors to the cranium above the gills, forming the posterior edge of the gill chamber. [2] The bone has scientific use as a means to determine the age of fishes. The lobe-finned fishes share this arrangement.
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Such gills are characteristic of cartilaginous fish such as sharks and rays, as well as deep-branching vertebrates such as lampreys. In contrast, bony fishes have a single outer bony gill covering called an operculum. Most sharks and rays have five pairs of gill slits, but a few species have 6 or 7 pairs. Shark gill slits lie in a row behind ...