Mollusca

Second largest phylum
Approximately 85,000 species
Comprises about 23% of all the named marine organisms
The phylum is typically divided into 7 or 8 taxonomic class, two are entirely extinct.
Cephalopod molluscs, such as squid, cuttlefish and octopuses are amongst the most neurologically advanced of all invertebrates
Either the giant squid or colossial squid is the largest known invertebrate species.
Gastropods (snails and slugs)  are the most numerous molluscs and account for 80% of the total classified species.