Parts of The Shell
The terminology used to describe the shells of gastropods includes:
- Aperture: the opening of the shell
- Lip = peristome: the margin of the aperture
- Apex: the smallest few whorls of the shell
- Body whorl: the largest whorl in which the main part of the visceral mass of the mollusk is found
- Columella: the "little column" at the axis of revolution of the shell
- Operculum: the "trapdoor" of the shell
- Parietal callus: a ridge on the inner lip of the aperture in certain gastropods
- Periostracum: a thin layer of organic "skin" which forms the outer layer of the shell of many species
- Peristome: the part of the shell that is right around the aperture
- Plait: folds on the columella.
- Protoconch: the nuclear whorls; the larval shell, often remains in position even on an adult shell
- Sculpture: ornamentation on the outer surface of a shell
- Lira: one kind of shell sculpture
- Siphonal canal: an extension of the aperture in certain gastropods
- Spire: the part of the shell above the body whorl.
- Suture: The junction between whorls of most gastropods
- Teleoconch : the entire shell without the protoconch; the postnuclear whorls.
- Umbilicus: in shells where the whorls move apart as they grow, on the underside of the shell there is a deep depression reaching up towards the spire; this is the umbilicus
- Varix: on some mollusk shells, spaced raised and thickened vertical ribs mark the end of a period of rapid growth; these are varices
- Whorl: each one of the complete rotations of the shell spiral
Read more about this topic: Gastropod Shell
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