Aperture (mollusc)

Aperture (mollusc)

The aperture is the main (or only) opening in the 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.

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.

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 "bacon", which help make the soft parts of the animal less vulnerable to predation.

For convenience of reference, the apertural edge or margin of a gastropod shell is divided into three areas or walls:

* The parietal wall: the area next to the penultimate whorl of the shell
* The columellar wall: the wall next to the columella
* The palatal wall: the outer free wall of the final whorl of the shell

Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Aperture (disambiguation) — An aperture is an opening, in particular one whose size determines what can or cannot pass through. The term can in particular refer to:*Aperture of an optical system, the opening that limits the amount of light that can pass through *Aperture… …   Wikipedia

  • Mollusc shell — Closed and open shells of a marine bivalve, Petricola pholadiformis. A bivalve shell is composed of two hinged valves which are joined by a ligament …   Wikipedia

  • Whorl (mollusc) — A whorl is a single, complete 360° turn in the spiral growth of a mollusc shell. A mollusc shell is basically a long tube, usually coiled in a spiral for strength and compactness. The number of whorls in the shell depend on various factors in the …   Wikipedia

  • Sculpture (mollusc) — Sculpture on a mollusc shell is whatever natural 3 dimensional ornamentation exists on the outer surface of a shell, apart from the basic shape of the shell itself. The term sculpture is most often applied to the shells of gastropods and bivalves …   Wikipedia

  • Turbo (mollusc) — Taxobox name = Turbinidae image caption = Turbo marmoratus regnum = Animalia phylum = Mollusca classis = Gastropoda subclassis = Prosobranchia ordo = Archaeogastropoda superfamilia = Trochacea familia = Turbinidae genus = Turbo genus authority =… …   Wikipedia

  • Apex (mollusc) — The apex is a word most often used to mean the tip of the spire of the shell of a gastropod. It is the first formed, and therefore the oldest, part of the shell. To be more precise, the apex would usually be where the tip of the embryonic shell… …   Wikipedia

  • Freshwater pearl mussel — The exterior of the shell of Margaritifera margaritifera Conservation status …   Wikipedia

  • Ranella olearius — Taxobox name = Ranella olearius image caption = status = LR/nt status system = IUCN2.3 regnum = Animalia phylum = Mollusca classis = Gastropoda ordo = Sorbeoconcha infraordo = Neogastropoda familia = Ranellidae genus = Ranella species = R.… …   Wikipedia

  • Eye — For other uses, see Eye (disambiguation), Ocular (disambiguation), Ocular, and Oculus. For taxon specific articles, see human eye, simple eye in invertebrates, mollusc eye, and arthropod eye. Eye …   Wikipedia

  • Body whorl — The body whorl in a mollusc shell is the most recently formed whorl of a spiral shell, terminating in the aperture. The size of the body whorl differs greatly according to shell morphology. In shells in which the rate of whorl expansion after… …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”