“All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.

All vertebrates possess the defining features of chordates—namely, a notochord, dorsal hollow nerve cord, and pharyngeal slits at some stage of their life cycle—therefore, they belong to the phylum Chordata; however, not all chordates develop a vertebral column (backbone), as seen in the subphyla Urochordata and Cephalochordata which lack a vertebral column, thus all vertebrates are chordates, but the reverse is not true.