Question

Notochord occurs in the adult animal of:

• A. Osteichthyes
• B. Chondrichthyes
• C. Protochordata
• D. Amphibia

Answer 1

Answer: (C)

Protochordata

The notochord is a cartilaginous rod located dorsally in the body. It is present in the embryonic stages of all and adult stages of lower chordates. In higher chordates (from Pisces onwards) it develops into a vertebral column.

A) Osteichthyes is a class of the superclass Pisces. It is included in higher chordates and hence has no notochord in the adult stage.

B) Chondrichthyes is a class of the superclass Pisces and is a higher chordate. Hence, it does not have a notochord in the adult stage.

C) Protochordata is an informal category of animals that includes hemichordata, Urochordata, and Cephalochordata. This category has a notochord in the adult stage.

D) Amphibia is a class included in the superclass Tetrapoda. These are higher chordates and do not have a notochord in the adult stage.

Hence, the correct answer is 'Protochordata'.