The varix is a thickened axial ridge, a subcylindrical protrusion, in the shell which exists in some families of marine gastropods. It is an important shell character in generic classification. A varix is located at intervals around the whorl, and is formed by considerable thickening of the outer lip during a resting stage in the growth of the shell. In other words, in gastropods whose shells have varices, the shells are characterised by episodic growth - the shell grows in spurts, and during the resting phase the varix forms.
In many gastropod whose shells have varices, for example the Cassinae, the varix is essentially merely a thickening and swelling of the shell at that point. But in some genera within the family Muricidae, such as Chicoreus, Hexaplex, Pteropurpura and Pterynotus, and also within the genus Biplex, of the family Ranellidae, the varices are characterised by elaborate ruffles, frills or lamellae. Some other genera, for example Murex, are armed with protective spines which may be straight or curved, and which are formed by the varices closing or curling around their axis.
Muricidae is a large and varied taxonomic family of small to large predatory sea snails, marine gastropod mollusks, commonly known as murex snails or rock snails. With over 1,700 living species, the Muricidae represent almost 10% of the Neogastropoda. Additionally, 1,200 fossil species have been recognized. Numerous subfamilies are recognized, although experts disagree about the subfamily divisions and the definitions of the genera. Many muricids have unusual shells which are considered attractive by shell collectors and by interior designers.
The operculum is a corneous or calcareous anatomical structure like a trapdoor that exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc.
The Cassidae are a taxonomic family of medium-sized, large, and sometimes very large sea snails commonly called helmet snails or bonnet snails. These are marine gastropod mollusks in the superfamily Tonnoidea and the clade Littorinimorpha.
The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some gastropods appear shell-less (slugs) but may have a remnant within the mantle, or in some cases the shell is reduced such that the body cannot be retracted within it (semi-slug). Some snails also possess an operculum that seals the opening of the shell, known as the aperture, which provides further protection. The study of mollusc shells is known as conchology. The biological study of gastropods, and other molluscs in general, is malacology. Shell morphology terms vary by species group.
The molluscshell is typically a calcareous exoskeleton which encloses, supports and protects the soft parts of an animal in the phylum Mollusca, which includes snails, clams, tusk shells, and several other classes. Not all shelled molluscs live in the sea; many live on the land and in freshwater.
Pteropurpura festiva, commonly known as the festive murex, is a species of predatory sea snail, a marine gastropod mollusk in the family Muricidae, the rock snails. Native to the Eastern Pacific, these sea snails grow to 34–67 mm in length.
Inodrillia amblytera is a species of sea snail, a marine gastropod mollusk in the family Horaiclavidae.
Danilia weberi is a species of sea snail, a marine gastropod mollusk in the family Chilodontidae.
Calliostoma columnarium, common name the cape pillar top shell, is a species of sea snail, a marine gastropod mollusk in the family Calliostomatidae.
Dermomurex gofasi is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Favartia kalafuti is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Maxwellia gemma, commonly known as gem murex, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Purpurellus pinniger is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Vokesimurex recurvirostris, common name : the bent-beak murex, is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Vokesimurex samui is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Vokesimurex tryoni is a species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex snails or rock snails.
Maxwellia is a genus of sea snails, marine gastropod mollusks in the family Muricidae, the murex snails or rock snails.
Cerithium lindae is a species of sea snail, a marine gastropod mollusk in the family Cerithiidae.
Linatella caudata, common name : the Girdled triton or Poulsen's Triton, is a species of predatory sea snail, a marine gastropod mollusk in the family Cymatiidae.
Muricopsinae is a taxonomic subfamily of predatory sea snails, marine gastropod mollusks within the large family Muricidae, the murex snails and rock snails.
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