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b. the bony plate in certain gastropods covering the opening of the shell when the body is withdrawn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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

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.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
(2006) recognized "internal germination opercula" in some of the genera, e.g., Harpephyllum and Spondias.
Issues with the use of opercula have largely focused on the clarity and readability of surface rings.
The results from that workshop indicated that, with increased experience by the staff, the use of sectioned otoliths from tautog may yield age estimates of higher precision than the use of opercula. After that workshop, sectioned otoliths have been used as a supplementary method for age determination (ASMFC (2)).
Snails previously reported as surviving fish gut passage were members of the subclass Prosobranchia, like valve snails, and were thus equipped with opercula (Haynes et al., 1985; Aarnio and Bonsdorff, 1997).
Most of the archaeological materials that were removed from the site were the smaller, more fragmented pieces such as Turban (Turbo sp.) shell and opercula, fragments of crustacean and small bivalves (Table 1).
Live and dead adult and subadult Bellamya japonica with their opercula missing and with part or most of their large, muscular foot bitten off by muskrats have been found singly or in clusters ("middens") of up to 64 individuals on dozens of occasions from September 1993 to present in shallow waters (0-0.5 m deep) along the shoreline of Salt Fork Lake.
The dyslexic participants did, however, have type II-III opercula and extra Heschl's gyri (Figure 7).
This could be accomplished actively with radical changes in behavior (e.g., swimming backwards with opercula flared).
The occurrence of calcareous deposits in rissooidean opercula is sporadic, even within families and genera.