operculum

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operculum

1. Zoology
a. the hard bony flap covering the gill slits in fishes
b. the bony plate in certain gastropods covering the opening of the shell when the body is withdrawn
2. Botany the covering of the spore-bearing capsule of a moss
3. Biology any other covering or lid in various organisms

Operculum

 

the fold of skin that covers the outside of the gill slits in the majority offish (except the shark and ray) and in the larvae of amphibians, especially tadpoles. The operculum of fish of the class Osteichthyes has bones. In the majority offish the operculum plays an active role in breathing: when it is lifted, a vacuum is created in the gill cavity, and water passes from the mouth and pharyngeal cavities into the gill cavity by way of the gill apparatus. It is possible to determine the age of some fish according to the annual rings on the operculum bones.

operculum

[ō′pər·kyə·ləm]
(anatomy)
The soft tissue partially covering the crown of an erupting tooth.
That part of the cerebrum which borders the lateral fissure.
(biology)
A lid, flap, or valve.
A lidlike body process.
References in periodicals archive ?
Before the pre-inverted tubule inverts, a clear transition at its junction with the capsule has been observed in both operculate (Skaer, 1973: Holstein.
Although the precise details of how the tubule is anchored to the capsule wall may differ between operculate and non-operculate nematocysts, we infer that what Holstein (1981) termed the interna is the electron-dense, thick layer we saw along the inside of the capsule only at the apical end, where it lies against the layers that can be traced completely around the capsule wall (e.
The reports were based on characteristic large operculate eggs having been found in routine stool examinations conducted during schistosomiasis surveys.
Capsule operculate (lower portion rarely tardily loculical) with a short calyptrate indehiscent operculum with osseous endocarp becoming free from membranous longer portion; annual herb; stems strigose throughout from only simple trichomes to 1.
Variable-sized operculate snails of tropical regions of Asia and Africa.
Small to medium-sized operculate snails of tropical regions of Africa.
sinensis is transmitted by a wide range of operculate snails, Parafossarulus manchouricus being the main one (2).