- A Cephalochordata retains the notochord only in the larval tail before resorption at metamorphosis; Urochordata retains it for life
- B Cephalochordata retains the notochord from head to tail throughout life; Urochordata retains it only in the larval tail
- C Both groups retain a fully ossified vertebral column replacing the notochord in adults
- D Neither group develops a notochord at any embryonic or adult stage
Correct answer: B. Cephalochordata retains the notochord from head to tail throughout life; Urochordata retains it only in the larval tail
Explanation: In Cephalochordata (Amphioxus/Branchiostoma), the notochord persists from head to tail throughout life. In Urochordata (Ascidia), the notochord is present only in the larval tail and is lost in the adult.
Concept context
Phylum-level classification of the animal kingdom from Porifera to Chordata, based on body symmetry, coelom, and segmentation. One of the most example-heavy chapters for NEET.