Question

Based on the notochord, chordates are classified into ancient and .

• A. non-chordates
• B. protochordates
• C. invertebrates
• D. vertebrates

Answer 1

Answer: (B), (D)

vertebrates

Based on the occurrence of the notochord, chordates are subdivided into protochordata and vertebrata. Protochordata includes the primitive chordates, and includes two sub-phyla: Urochordata (or tunicata) and Cephalochordata.
In Urochordata, notochord is present only in the larval tail, while in Cephalochordata, it extends from the head to tail region, and is persistent throughout the animal's life.
The members of sub-phylum Vertebrata possess notochord during the embryonic period. The notochord is replaced by a cartilaginous or bony vertebral column in the adult. Vertebrata is the sub-phylum that includes fishes, amphibians, reptiles, birds and mammals.