Gastropods:
Snails use their radula (a tongue like structure with hard teeth) to scrape food into their mouth where the food goes through the buccal cavity and stomach. The food gets digested into here. The food then goes into the intestine where the nutrients are absorbed. Whatever is left then goes out the anus.
Bivalvia:
They filterfeed by having water go through their incurrent pole and filter it through the mantle. The food then attaches to mucus on the gills of clams.
Cephalopoda:
When squids catch their prey, they use their tentacles and arms to move them to their beak. The beak then breaks apart prey and enters the radula. The food gets take to the stomach where digestive glands take the nutrients to the blood. The undigested part are then released through the anus.
A Study In Biology 