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Aperture
 

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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.