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An operculum is an anatomical feature, a stiff structure resembling a lid or a small door that opens and closes, and thus controls contact between the outside world and an internal part of an
An operculum is an anatomical feature, a stiff structure resembling a lid or a small door that opens and closes, and thus controls contact between the outside world and an internal part of an animal
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...
. Examples include:
* An operculum (gastropod), a single lid that (in its most complete form) closes the aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane.
An ...
of the shell when the animal is retracted, and thus protects the internal soft parts of the animal that are not completely covered by the shell. 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.
* An operculum (fish), a flap that covers the gills in bony fish
Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartil ...
es and chimaera
Chimaeras are cartilaginous fish in the order Chimaeriformes , known informally as ghost sharks, rat fish, spookfish, or rabbit fish; the last three names are not to be confused with rattails, Opisthoproctidae, or Siganidae, respectively.
At ...
s.
* The cover that rapidly opens a cnida
A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive Cell (biology), cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The pre ...
of a cnidaria
Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter.
Their distinguishing feature is cnidocytes, specialized cells that ...
n such as a jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbre ...
or a sea anemone. The lid may be a single hinged flap or three hinged flaps arranged like slices of pie.
* In insects, the operculum is the name for one or more lids covering the tympanal cavity. A subgenital operculum is exhibited in phasmoidea and grasshoppers and allies ( orthoptera).
See also
*Aptychus
An aptychus is a type of marine fossil. It is a hard anatomical structure, a sort of curved shelly plate, now understood to be part of the body of an ammonite. Paired aptychi have, on rare occasions, been found at or within the aperture of ammon ...
: A structure in ammonites which usually consists of two plates, and which was long thought to be a form of double operculum, but which more recently has been proposed to have been a jaw mechanism.
References
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