A group of researchers procured some fish-like animals and upon investigation the following characters were observed: Which of the following species of animals did they consider to fit best with these characters ?
- Scoliodon sp.
- Exocoetus sp.
- Petromyzon sp.
- Branchiostoma sp.
Answer
(3) Petromyzon sp.
Solution
As per NCERT, cyclostomes are ectoparasites on some fishes; they have a sucking and circular mouth without jaws, a body devoid of scales and paired fins, 6–15 pairs of gill slits and a cartilaginous cranium and vertebral column.
All the observed characters fit class Cyclostomata.
∴ Petromyzon (Lamprey) fits best.
( Scoliodon – cartilaginous fish with jaws; Exocoetus – bony fish; Branchiostoma – cephalochordate.)
Answer: (3)