Answer: Larval tail only.
- A Adult trunk region
- B Larval tail only
- C Entire body always
- D Gill region only
Correct answer: B. Larval tail only
Explanation: In urochordates the notochord is present only in the larval tail and is lost in the adult.
Moving across the animal phyla, body organisation becomes progressively more complex: from no symmetry and cellular organisation (Porifera) through radial/diploblastic (Cnidaria), bilateral/acoelomate (Platyhelminthes), pseudocoelomate (Nematoda), to a true coelom with full organ systems (Annelida and beyond).
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.