Question

Which one of the following belongs to dipnoi?
A. Lungfish
B. Catfish
C. Rat fish
D. Star fish

Answer 1

Hint: Dipnoi is a subclass or order of fishes that includes sarcopterygian fish. They are commonly called lung fishes. They have many extinct species of fish.

Complete Answer:
- Lungfish are the freshwater fishes that belong to the subclass dipnoi. They are known for retaining their characteristics primitive among the bony fish or osteichthyes, sarcopterygii, including ability to breath and presence of lobed fins along with developed internal skeleton. They are one of the endangered species. Today there are only six species.
- Catfish: they are a group of ray-finned fishes that belongs to class Actenopterygii. They are called catfish because their barbels resemble a cat's whiskers. They are omnivorous and feed on crawfish, algae, insects, snails and other plants mostly during night.
- Rat fish: they are the cartilaginous fish that belong to class Chondrichthyes. They are called so because they have a rat-like pointed tail. They are also called chimaeras.
- Star fish: they are the star shaped echinoderms that belong to class Asteroidea. They resemble fish as they live underwater but they are not true fish as they do not have gills, fins and scales like normal fishes.

Therefore the correct answer is (A) Lungfish.

Note: Lungfish have a well-defined feature that their lungs are attached to pharynx and larynx without the involvement of trachea whereas other fishes breathe through gills or modified vascular gas bladders. And also the lungs of lungfish are homologous to that of tetrapods.