Apparently nobody had any interest in answering to this question for a long time (and , as I discovered, very few people had any interest in reading the answers). Typically, this is one reason why I attempted a schematic essay. I limited myself to basically collecting the number of non-extinct, saltwater Phyla present in the seas with more than 10000 species. The phylum Vertebrates is dealt with a particular sympathy. Aren’t we all vertebrates?