Name the phylum in which pharyngeal gill slits are present but notochord is absent.
Phylum Hemichordata (Now considered as Nonchordata).
Name the phylum in which dorsal nerve tube, notochord and pharyngeal gill clefts are present.
Animals with a double ventral notochord, dorsal nerve cord, pharyngeal gill slits and a post anal tail are placed in the highly evolved phylum called_____.