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The radula (US: / ˈ r æ dʒ ʊ l ə /; pl.: radulae or radulas) [1] is an anatomical structure used by mollusks for feeding, sometimes compared to a tongue. [2] It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus .
The mollusc does not elongate when crawling and the location of the head is revealed when it thrusts out its rolled rhinophores from beneath the shell. At the base of the rhinophores are a pair of eyes, and beneath is a cleft which contains the mouth. The radula is broad and is armed with many small teeth.
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 buccal mass is the first part of the digestive system, and consists of the mouth and pharynx. The mouth includes a radula, and in most cases, also a pair of jaws. The pharynx can be very large, especially in carnivorous species. Many carnivorous species have developed a proboscis, containing the oral cavity, radula, and part of the ...
In terrestrial pulmonate gastropods, eye spots are present at the tips of the tentacles in the Stylommatophora or at the base of the tentacles in the Basommatophora.These eye spots range from simple ocelli that cannot project an image (simply distinguishing light and dark), to more complex pit and even lens eyes. [6]
The radula is used to scrape microscopic algae off the substratum. The mouth cavity itself is lined with chitin and is associated with a pair of salivary glands. Two sacs open from the back of the mouth, one containing the radula, and the other containing a protrusible sensory subradular organ that is pressed against the substratum to taste for ...
The radula primarily functions to scrape bacteria and algae off rocks, and is associated with the odontophore, a cartilaginous supporting organ. [16] The radula is unique to the molluscs and has no equivalent in any other animal. Molluscs' mouths also contain glands that secrete slimy mucus, to which the food sticks.
The molluscs have the widest variety of eye morphologies of any phylum, [1] and a large degree of variation in their function. Cephalopods such as octopus, squid, and cuttlefish have eyes as complex as those of vertebrates, while scallops have up to 100 simple eyes. [2]