Answer: A body divided into proboscis, collar, and trunk, with a doubtful notochord.
- A Presence of a dorsal hollow nerve cord identical to vertebrates in routine practice
- B A body divided into proboscis, collar, and trunk, with a doubtful notochord
- C Possession of a vertebral column overall in most cases under typical conditions
- D Presence of paired appendages like fins according to standard textbooks
Correct answer: B. A body divided into proboscis, collar, and trunk, with a doubtful notochord
Explanation: Hemichordates like Balanoglossus have a body divided into proboscis, collar, and trunk regions, and although they show some chordate-like features, the presence of a true notochord is doubtful, distinguishing them from true Chordata.
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.