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

Chordates are classified as vertebrates and invertebrates.Invertebrates include urochordata and cephalochordata. These two donot have a vertebrae but are considered as chordates as they show primitive chordate characters like pharyngeal gill slits,post anal tail,notochord and nerve chord.In we vertebrates this notochord is replaced by vertebrae. We too obey the basic chordate characters in embryonic stage. Hence all vertebrates (we) are chordates but all chordates ( invertebrates) are not vertebrates.☺