a hard flap serving as a cover for (a) the gill slits in fishes or (b) the opening of the shell in certain gastropods when the body is retracted
A covering flap or lidlike structure in plants and animals, such as a gill cover
Origin: From operire.
The operculum, meaning little lid, is a corneous or calcareous anatomical structure like a trapdoor which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails. In other words, this structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc. The operculum is attached to the upper surface of the foot and in its most complete state, it serves as a sort of "trapdoor" to close the aperture of the shell when the soft parts of the animal are retracted. The shape of the operculum varies greatly from one family of gastropods to another. It is fairly often circular, or more or less oval in shape. In species where the operculum fits snugly, its outline corresponds exactly to the shape of the aperture of the shell and it serves to seal the entrance of the shell. A small air-hole may remain to aid respiration, especially during aestivation. Many families have opercula that are reduced in size, and which are not capable of closing the shell aperture. Opercula have sometimes been modified: in the Strombidae the operculum is claw-shaped and is used to push into the substrate in a leaping form of locomotion.
Chambers 20th Century Dictionary
ō-pėr′kū-lum, n. (bot.) a cover or lid: (zool.) the plate over the entrance of a shell: the apparatus which protects the gills of fishes:—pl. Oper′cula.—adjs. Oper′cular, belonging to the operculum; Oper′culate, -d, having an operculum; Operculif′erous; Oper′culiform; Operculig′enous; Operculig′erous. [L.,—operīre, to cover.]
The numerical value of operculum in Chaldean Numerology is: 8
The numerical value of operculum in Pythagorean Numerology is: 7
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