Mollusk

Mollusca Temporal range: Cambrian–Recent PreЄ Є O S D C P T J K Pg N
Tonicella lineata, a polyplacophoran or chiton, anterior end towards the right
Scientific classification
Kingdom:	Animalia
Superphylum:	Lophotrochozoa
Phylum:	Mollusca Linnaeus, 1758
Classes
See text.
Diversity
85,000 recognized living species.

See text.

The molluscs (or mollusks/ˈmɒləsks/) compose the large phylum of invertebrate animals known as the Mollusca. Around 85,000 extant species of molluscs are recognized. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and in anatomical structure, but also in behaviour and in habitat. The phylum is typically divided into 9 or 10 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish and octopus, are among the most neurologically 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 most numerous molluscs in terms of classified species, and account for 80% of the total. The scientific study of molluscs is called malacology.