A radula is tonugelike organ that all members of the phylem have, except for bivalves, who obtain their food by filter feeding. The radula can be protruded or moved by the animal. It is covered with a row of backward pointing teeth. Some members of this phylum use the radula for scraping algea or other food materials off of a substrate. Active predetors use the radula for puncturing their prey and sucking out the food.
Mollusks usually have three distinct sections.
Head, where all the sensory equpment is concentraited. The organs of reproduction Foot Nitrogen-rich waste is removed by one or two nephridia. Mollusks were one of the first evolutionary lines to have developed efficent exretory system.