Question

A Jawless fish, which lays eggs in fresh water and whose ammocoetes larvae after metamorphosis return to the ocean is

(a) Eptatretus

(b) Myxine

(c) Neomyxine

(d) Petromyzon

Answer 1

Correct option  (d) Petromyzon

Explanation:

Petromyzon (the lamprey) belongs to the section Agnatha of the subphylum-Vertebrata. They have long, greenish brown, cylindrical body with smooth scaleless, slimy skin, jawless mouth, etc. They lay eggs in freshwater, but their ammocoete larvae (lower) after metamorphosis return to the ocean.