Is a octopus in the phylem chordate?

No, an octopus is not in the phylum Chordata; it belongs to the phylum Mollusca. Specifically, octopuses are classified within the class Cephalopoda, which also includes squids and cuttlefish. Chordates are characterized by features such as a notochord, dorsal nerve cord, and pharyngeal slits, none of which are present in octopuses.