Animals of this class are marine,but migrate to freshwater for spawning.

Agnatha includes:

Select the incorrect statements with respect to Cyclostomes:
$(a)$ They lack scales and paired fins.
$(b)$ They have a circular mouth with jaws.
$(c)$ They bear $6-15$ pairs of gills.
$(d)$ They migrate to deep sea for spawning.
Choose the most appropriate answer from the options given below:

Which of the following serves as the respiratory organ in animals belonging to the class $Cyclostomata$?

What is found in the skin of Cyclostomata?

Cyclostomata belongs to which division?