There are two invertebrate subphyla: the Urochordata, or tunicates tunicate, marine animal of the phylum Chordata, which also includes the vertebrates. The adult form of most tunicates (also called urochordates) shows no resemblance to vertebrate animals, but such a resemblance is evident in the larva......hordata. (kordÄ`kÃ´rdÄ,âtÉ`â) , dae dÃ¤ phylum of animals having, a notochord or dorsal, stiffening rod as the chief internal skeletal support at some stage of. Their development most chordates (are vertebrates animals), with backbones but the phylum also includes some small marine. invertebrate animals