Mollusca
Mollosca, or Mollusks consists of the large 85,000 of marine invertebrate phylum. All mollusks are soft bodied with a hard shell surrounding it for protection. Mollusks are usually herbivores, carnivores or filter-feeders. Mollusks have a dorsal shaped body. They feed through tongue with teeth along the inside called a radula. After that the food makes it way past the radula and through the digestive glads to the intestine. Mollusks have a foregut, so the food later is excreted through their anus, which is a different hole.
Snail (Gastropod)
The Snail or Gastropod is one of the more common Mollusca's. Commonly known for being slow and defenseless, it too has a somewhat complex digestive system. Food starts off at the Buccal Mass, which contains the mouth and the Pharynx. The Radula is used to bring food into the mouth, and for carnivores, the radula is used to stab and bring pray closer to the mouth. Salivary glads help bring food down to the Oesophagus, which connects to the stomach. The stomach is a "U" shape, and has three components: The Gizzard, the Vestibule and the style sac. Working with the hepatopancreas, the mid gut glads help to make digestive enzymes. The Glandular pouch located in front of the vestibule contains execration glands. Food makes its way toward the intestine, which coils around the Kidney and has three parts: The Caecum, the three parts of the intestine and the anal papilla. A muscular Sphincter helps control food flowing though out the body.
Squid (Teuthida)
The Squid or Teuthida has a more complex digestive system. Most of its digestive organs are located in the midsection of is body. It is complete with a mouth, an anus and a complex stomach. Food begins entering the mouth and into the caecum for digestion. Food then goes to the liver, which contains the digestive glands, and cells bring it up and break it down. After the food that is able to be broken down, the rest of the food is packed away and stored to later be discharged through the anus and mantle cavity.
Limpet ( Phyllaplysia Taylori)
Limpets are grazers and also have a radula to help in scrapping algae off the sea rocks. Food enters the mouth located on the ventral surface of their head. The mouth opens the buccal cavity which opens to the esophagus and leads to the stomach. A Sphincter separates the stomach from the intestine. The intestine loops around in the visceral mass and then food is execreted through the rectum in the mantle cavity.