NEETBotanyAnimal Kingdom
Consider the marine animals Ascidia, Salpa, and Doliolum. Which of the following statements correctly describes the central supporting axis (notochord) in these organisms?
Options
- AIt is present only in the larval tail and is lost in the adult.
- BIt extends from head to tail and is persistent throughout their life.
- CIt is replaced by a cartilaginous or bony vertebral column in the adult stage.
- DIt is completely absent at all stages of their life cycle.
Correct answer
A. It is present only in the larval tail and is lost in the adult.
Step-by-step solution
The organisms Ascidia, Salpa, and Doliolum are examples of the subphylum Urochordata (Tunicata). A defining characteristic of Urochordata is that the notochord is present exclusively in the larval tail and does not persist in the adult stage. Cephalochordates have a notochord extending from head to tail throughout life, while vertebrates have it replaced by a vertebral column in adults. Answer: It is present only in the larval tail and is lost in the adult.