The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where the head-foot part of the body of the animal emerges for locomotion, feeding, etc. The term aperture is used for the main opening in gastropod shells, scaphopod shells, and also for Nautilus and ammonite shells.

Jan 3, 2025 · The aperture is the entrance to the shell, from which the snail will extend its body. Living sea snails often can retreat into the shell and cover it with a flat, tough plate called an operculum . The operculum can often be used to identify living shells by species, but is rarely (if ever) found on dead shells.

The shell is secreted along the outer lip of the aperture by the fleshy part of the animal called the mantle, first by outward additions to the shell lip and then by secretion of inner thickening layers.

When facing a snail shell in the apertural view, the aperture pointing to the bottom, in most species one can easily see that the shell whorls run to the right. On the other hand, there are also snail families, such as the door snails ( Clausiliidae ), among which most species are left-handed, with some exceptions.

The shell is shown in its entirety, with its aperture facing the viewer, and the apex at the top. If the aperture is on the right side when viewed like this, then the shell-coiling is "right-handed" or dextral; if the aperture is on the left side when viewed like this, the shell has "left-handed" or sinistral shell-coiling.

Apr 18, 2024 · What is a shell aperture? The aperture is the primary opening in the shell that the mollusk body, foot, and head enter and exit in order for it to interact with the environment. Living gastropods have an operculum , a hard calcified "door" that they can use to plug up the aperture.

In the shell of gastropod mollusks (a snail shell), the lip is the free margin of the peristome (synonym: peritreme) or aperture (the opening) of the gastropod shell. In dextral (right-handed) shells (most snail shells are right-handed), the right side or outer side of the aperture is known as the outer lip ( labrum ).

aperture—the opening of a snail shell from which the snail's soft body emerges, sometimes called the "mouth." apex —the top end of a shell's columella, opposite the umbilicus and furthest from the aperture.

the opening of the shell through which the animal can expand (never used for the mouth in the soft parts). In the Limacinidae and Clioinae the aperture is rounded or triangular and continuous (see A in figure of Thecosomata below).

Shell thick, similar in shape to that of a cowrie, with a series of teeth on the inside of the outer lip of the aperture; aperture not decidedly wider in its anterior half than elsewhere; height about 3 mm