Mollusks are a large phylum of invertebrate animals, that can be found in marine, freshwater and terrestrial habitats. They are highly diverse, not only in size and in anatomical structure, but also in behavior and in habitat. The most commonly recognized groups of mollusks are cephalopods (squids, octopus, etc.), gastropods (Snails, slugs, etc.) and bivales (Clams, oysters, etc.).