Mollusca
The molluscs or mollusks, compose the largest phylum of invertebrate animals known as the phylum Mollusca. There are around 85,000 known species of molluscs. Molluscs are the most numerous marine phylum, comprising almost 23% of all the known marine organisms. Some species of molluscs also live in freshwater and some even live in habitats on land. They are highly diverse, not only in size and in thier structure, but also in their behaviour and where they live. The phylum is normally divided into 9 or 10 taxonomic classes, there are two extinct taxonomic classes. Cephalopod molluscs, such as a squid, cuttlefish and octopus, are among the most advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods (snails and slugs) are by far the largest molluscs in terms of classified species, and account for 80% of the total.