Radula

Ghost Slug teeth

Radula docoglosse

Land Snail radula tracks.jpg

Radula diagram3

Tentacle, mouth (with radula) and eggs of Planorbarius corneus snails

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Deroceras laeve radula 400 orcein.jpg

Radula is a structure found in the mouths of most molluscs, except for bivalves. It is a specialized feeding organ that is used to scrape or cut food before ingestion. The radula is often compared to a tongue, but it is equipped with numerous tiny teeth, known as denticles, which are used to process food.

Structure

The radula is composed of a chitinous ribbon-like membrane that bears rows of microscopic teeth. These teeth are continuously replaced as they wear down. The radula is supported by a cartilaginous structure called the odontophore, which provides a base for the radula to move against. The radula and odontophore together form a complex apparatus that can be extended out of the mouth to scrape food from surfaces.

Function

The primary function of the radula is to aid in the feeding process. Molluscs use the radula to scrape algae, detritus, or other food particles from surfaces. In some species, the radula is adapted to bore into the shells of other molluscs or to tear flesh from prey. The action of the radula is controlled by a series of muscles that allow it to move back and forth, effectively rasping food particles into the mouth.

Variations

The structure and function of the radula can vary significantly among different groups of molluscs. For example:

• In gastropods, the radula is typically used to graze on algae or plant material.
• In cephalopods, such as squid and octopus, the radula is often used in conjunction with a beak to process prey.
• In some predatory snails, the radula is modified to inject venom into prey.

Evolutionary Significance

The radula is considered an important evolutionary adaptation that has allowed molluscs to exploit a wide range of ecological niches. The diversity in radula structure and function among different molluscan groups is a testament to its evolutionary success.

Research and Study

The study of radulae can provide valuable insights into the feeding habits and ecological roles of molluscs. Radulae are often examined under microscopes to study their morphology and to identify species based on the unique patterns of their teeth.

See Also

• Mollusca
• Gastropoda
• Cephalopoda
• Bivalvia
• Odontophore