Question

The notochord is present in larval stages but retrogressive metamorphosis results in its absence in adults. This phenomenon is seen in:

• A. Hemichordata.
• B. Urochordata.
• C. Cephalochordata.
• D. Euchordata

Answer 1

The correct option is B Urochordata.

The animals of the phylum Urochordata have a notochord and nerve cord, but only in larval stages. They exhibit retrogressive metamorphosis, whereby these structures are present in larval forms and absent in adult forms indicating the larvae are more advanced than the adults.

So, the correct answer is option B.