Science Fair Project Encyclopedia
Aperture (mollusc)
Aperture is the opening in the shell of a gastropod, through which the snail emerges. This opening can be closed, in most cases, by an operculum.
The aperture is generally elliptical or oval, but its upper part (the parietal wall) can have a truncated appearance. However, the aperture can also have many other forms: round, semicircular, trilobate or auriculate. This shape corresponds roughly to the cross-section of the last body whorl .
An aperture has three walls:
- parietal: wall of the penultimate whorl
- columellar: next to the columella
- palatal: outer free wall of the last whorl
The aperture is surrounded, except at the top, by the aperture margin.
10-26-2009 08:16:03
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details