Question

All vertebrates are chordates but all chordates are not vertebrates, why?

(1) All chordates possess notochord throughout their life.

(2) Notochord is replaced by vertebral column in adult of some chordates

(3) Ventral hollow nerve cord remains throughout life in some chordates.

(4) All chordates possess vertebral column.

Answer 1

Answer (2) Notochord is replaced by vertebral column in adult of some chordates

Sol. The correct answer is option (2) because the members of subphylum vertebrata possess notochord during the embryonic period. So, all vertebrates are chordates. The notochord is replaced by a cartilaginous or bony vertebral column in the adult vertebrates. In protochordates, vertebral column is not formed. In urochordates, notochord is present only in tail region in larval stage and in cephalochordates, it persists throughout life so all chordates are not vertebrates.

Answer 2

In vertebrates notochord is replaced by vertebral Column however vertebral coloumn is not present in protochordates,Therefore all vertebrates are not chordates but all chordates are vertebrates .