Feeding + Digestion

Most mollusks are herbivores, carnivores, or filter feeders though there are some species that are detritus feeders or are parasitic. Many mollusks (ie. snails and slugs) feed through a tongue shaped structure called a radula. A radula is a layer of flexible skin with hundreds of tiny teeth making it appear like sandpaper. Inside the radula there is stiff rod of cartilage. It places the tip of the radula on the food and pulls the flexible area of skin back and forth over the cartilage. Herbivores use their radula to scrap algae off of surfaces in the water or to eat the buds and roots of flowers on land plants. Carnivores extend their radula into the shell of the prey and tear up and swallow the preys tissue. Mollusks have a very complex digestive tract. After being taken by the radula, the food goes to the digestive glands and then to its intestine. Wastes exit via the anus and food enters the mouth. In the class gastopods, the mouth and anus are at the same end but are different openings. In some mollusks like oysters, clams and scallops, they use there gils to sift through food in the water. There is a layer of sticky mucus on the gills that the food sticks to and then is pushed to the mouth by cilia on the gills as well.