Question

In which of the protochordate animals notochord extends upto head region?

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

Answer 1

The correct option is D Cephalochordata

Protochordates are considered as the connecting link between vertebrates and invertebrates. These include three groups: Hemichordata, Urochordata and Cephalochordata.

• In Hemichordata, notochord is like structure is found in the roof of the buccal cavity which is called stomochord.
  
• In Urochordata, the notochord is usually present at larval stage and is restricted to tail. It disappears in the adult during retrogressive metamorphosis.
  
• In Cephalochordata, the notochord is persistent throughout the life and extends from tail up to the head region.
  

• Cyclostomata is a class under the subphylum Vertebrata in which notochord is replaced by the vertebral column.
  

So, the correct answer is D.