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A typical radula comprises a number of bilaterally-symmetrical self-similar rows of teeth rooted in a radular membrane in the floor of their mouth cavity. Some species have teeth that bend with the membrane as it moves over the odontophore, whereas in other species, the teeth are firmly rooted in place, and the entire radular structure moves as one entity.
Muscles that control the radula are shown in brown. The surface of the radula ribbon, with numerous teeth, is shown as a zig-zag line. The odontophore is part of the feeding mechanism in molluscs. It is the cartilage which underlies and supports the radula, a ribbon of teeth. [1] The radula is found in every class of molluscs except for the ...
The radula in this species is longer than the shell itself. It contains 1,920 teeth in 160 rows of 12 teeth each. Patella vulgata is found attached to firm substrates from the high shore to the edge of the sublittoral zone, although it predominates in areas of wave action. Its shell is conical, up to around 6 cm long, and lacks defined chirality.
Its teeth are small, mineralized, and arranged in a V-like form. Cymbula adansonii has a small rachidian tooth, which is the middle row of teeth in a gastropod’s set of radula. [6] It has a pluricuspid tooth in its radula, meaning it has several sets of cusps on one tooth. The cusps are composed of the mineral goethite and the gemstone opal.
In some gastropods, the aperture is narrowed by protruding plaits, which help make the soft parts of the animal less vulnerable to predation. The growth of the shell is provided for by non-continuous addition of minute layers to the aperture margin (also called peristome ) from the mantle border, the principal agent in the secretion of the shell.
The radula is typically taenioglossate with one central (rachidian) tooth, with on each side one lateral tooth and two marginal teeth. In 13 species the number of tooth rows increases during growth (Type I), while in 8 species the radula has a limited number of tooth rows (Type II).
Stylommatophora is the most diverse group of land snails and slugs. Pallial cavity forms a spacious, air-filled lung. Anus is located on the right side close to the pneumostome. Operculum is missing. Two pairs of tentacle are retractable and the posterior pair bears eyes on the tips. Radula typically has many small, quite uniform teeth per row.
The long radula has a long, narrow rhachidian tooth. It is lanceolate with its tip narrowand recurved. There are 26 laterals with the outer 5 without cusps. The inner ones are larger, with wide cusps and narrower bases. The outside of the laterals consists of 2 rows of uncini (the numerous small teeth-like or hook-like structures).