Darkfield photomicrograph, radula detail of garden snail, Helix sp.
The mouth of the gastropods is located below the anterior part of the mollusc. It opens into a pocket-like buccal cavity, containing the radula sac. The radula apparatus consists of two parts : 1) the cartilaginous base (the odontophore), with the odontophore protractor muscle, the radula protractor muscle and the radula retractor muscle. 2) the radula itself, with its longitudinal rows of chitinous and recurved teeth, the cuticula. The odontophore is movable and protrusible and the radula itself is movable over the odontophore. Through this action the radula teeth are being erected. The tip of the odontophore then scrapes the surface, while the teeth cut and scoop up the food and convey the particles through the esophagus to the digestive tract. These actions continually wear down the frontal teeth. New teeth are continuously formed at the posterior end of the buccal cavity in the radula sac. They are slowly brought forward to the tip by a slow forward movement of the ribbon, to be replaced in their turn when they are worn out. Teeth production is rapid (some species produce up to five rows per day). The number of teeth present depends on the species of mollusc and may number more than 100,000. Large numbers of teeth in a row (actually v-shaped on the ribbon in many species) is presumed to be a more primitive condition, but this may not always be true. The greatest number of teeth per row is found in Pleurotomaria (deep water gastropods in an ancient lineage) which has over 200 teeth per row. The shape and arrangement of the radular teeth is an adaptation to the feeding regime of the species. The teeth of the radula are lubricated by the mucus of the salivary gland, just above the radula. Food particles are trapped into this sticky mucus, smoothing the progress of food into the oesophagus. Certain gastropods use their radula teeth to hunt other gastropods and bivalve molluscs, scraping away the soft parts for ingestion. Cone shells have
Size: 3161px × 5551px
Photo credit: © Scenics & Science / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: darkfield, detail, file, garden, gastropod, grating, grinding, helix, microscope, pest, photomicrograph, radula, radulla, rasping, snail, sp.
