all vertebrates are chordates but all chordates are not vertebrates. justify.

The phylum, Chordata, is characterized by the presence of a notochord.  In sub-phylum Vertebrata, the notochord present in embryos gets replaced by a cartilaginous or bony vertebral column in adults. Thus in chordates notochord is present in the embryonic stage and may be present in some at only larval stage or throughout their life or may be replaced by vertebral column as in vertebrates. Thus, it can be said that all vertebrates are chordates as they posses notochord in embryonic stage but all chordates are not vertebrates as some of them do not posses vertebral column.