Mollusks are classified as herbivores, omnivores and carnivores, and their diets depend largely on the species and availability of food in a particular location. Some mollusks consume only algae and ocean plant matter, while others may eat shellfish and even small fish.
Regardless of whether they eat plant matter or living organisms, mollusks rely on large functional teeth to help grasp and consume prey. Mollusks that consume algae scrape their teeth along rock and coral surfaces to break off chunks of seaweed and grasses. Those that eat fish use their teeth as harpoons: their inherent weapons also contain potent poisons, which instantly kill prey.