Question

Crocodile and penguin are similar to whale and dogfish in which one of the following features?

• A. They have gill slits at some stage.
• B. They possess a solid single stranded central nervous system.
• C. They lay eggs and guard them till they hatch.
• D. They possess bony skeleton.

Answer 1

The correct option is A They have gill slits at some stage.

A. Crocodile, penguin, whale and dogfish, all these are chordates. So, all of them have gill slits at some stage (generally during early development). Gill slits are also called gill-clefts or pharyngeal-clefts.

B. Chordates have a hollow nerve cord which serves for the integration and coordination of the body activities.

C. They give birth to young ones.

D. They have mineralized dermal skeleton.

Hence, statement A is correct. So, the correct answer is 'They have gill slits at some stage'.