https://wiki-pathfindersonline.designerthan.at/api.php?action=feedcontributions&feedformat=atom&user=139.222.127.231 2026-05-19T11:49:26Z User contributions MediaWiki 1.35.5 https://wiki-pathfindersonline.designerthan.at/index.php?title=AY_Honors/Shells_-_Advanced/Answer_Key&diff=17541 2008-04-18T11:27:38Z

<p>139.222.127.231: </p> <hr /> <div>[[Image:Semicassis pyrum (base).JPG|thumb|250px|''[[Semicassis pyrum ]]'', which has a large aperture.]]<br /> The '''aperture''' is the main (or only) opening in the [[gastropod shell|shell of a gastropod]] or snail. It is where the soft parts of the animal emerge. In some [[prosobranch]] gastropods, the aperture is able to be closed, and even completely sealed, with a sort of door or [[operculum (gastropod)|operculum]].<br /> <br /> The aperture of many snail shells is round, rounded, elliptical or oval. This shape corresponds roughly to the cross-section of the [[body whorl]] of the shell.<br /> <br /> The aperture of a snail shell can have many other forms: semicircular, trilobate or auriculate. In some gastropods, the aperture is narrowed by protruding shell folds or &quot;bacon&quot;, which help make the soft parts of the animal less vulnerable to predation.<br /> <br /> For convenience of reference, the apertural edge or margin of a gastropod shell is divided into three areas or walls:<br /> <br /> * The parietal wall: the area next to the penultimate whorl of the shell<br /> * The columellar wall: the wall next to the columella<br /> * The palatal wall: the outer free wall of the final whorl of the shell<br /> <br /> <br /> {{Gastropod-stub}}<br /> <br /> [[Category:Animal anatomy]]<br /> [[Category:Molluscs]]</div>

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