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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 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 .
The shell of the sea snail Epitonium scalare has a sculpture of sharp vertical ribs known as "costae" The shell of the freshwater snail Bulinus forskalii has strong transverse ribs which form an angle at the shoulder. Sculpture is a feature of many of the shells of mollusks.
The shell formation requires certain biological machinery. The shell is deposited within a small compartment, the extrapallial space, which is sealed from the environment by the periostracum, a leathery outer layer around the rim of the shell, where growth occurs. This caps off the extrapallial space, which is bounded on its other surfaces by ...
Turritella is a genus of medium-sized sea snails with an operculum, marine gastropod mollusks in the family Turritellidae. [3] They have tightly coiled shells, whose overall shape is basically that of an elongated cone. The name Turritella comes from the Latin word turritus meaning "turreted" or "towered" and the diminutive suffix -ella. [4]
The shell of Stenotrema florida, a land snail or terrestrial gastropod.The periostracum of this species has minute hairs, giving the snail a velvety feel A yellowish tan periostracum is visible on the lower two thirds of this juvenile (8 cm) valve of the marine bivalve Spisula solidissima The dark periostracum is flaking off of this dried-out valve of the "ocean quahog", marine bivalve Arctica ...
The anal sulcus, also called the anal sinus or anal canal, in Gastropods is a notch, a shelly tube at the top of the aperture. [1] It is the first notch close to the suture. It houses the anal siphon through which the snail expels water and waste products. Shell of Drillia poecila Sysoev & Bouchet, 2001, showing the anal sulcus on top of the ...
Tonna galea, commonly known as the giant tun, is a species of marine gastropod mollusc in the family Tonnidae (also known as the tun shells). This very large sea snail or tun snail is found in the North Atlantic Ocean as far as the coast of West Africa, in the Mediterranean Sea and the Caribbean Sea.
In a study off the coast of Brazil, Dardanus venosus was found occupying eleven different kinds of gastropod shell including three different species of turban snail, . [3] Dardanus venosus often has the sea anemone Calliactis tricolor attached to its shell. It actively collects the anemone off a rock or removes it from an outgrown shell when it ...