Question

The respiratory organs in fish are-
A)Fins
B)Scales
C)Nostrils
D)Gills

Answer 1

Hint: The fish is an aquatic animal. It breathes in the dissolved oxygen present in water through their mouth and pumps it over the respiratory filaments. The respiratory organ of fish is present near the mouth.

Complete answer:
To solve this question, we must know about the respiratory organ in fish.
Respiration is a process by which exchange of gases takes place in an organism to carry out various physiological processes. Exchange of gases is taking in oxygen and giving out of carbon dioxide. Fish is an aquatic animal which takes in dissolved oxygen from the water.

Most aquatic animals have gills which help in taking in the dissolved oxygen. The unidirectional flow of water helps in pumping oxygen.
Fins- Fins are the locomotory organ present in fish.
Scales- It is the small rigid plate like structure present in the skin of fishes. It provides protection to the fish as it provides effective camouflage.
Nostrils- The nostril of the fish is called nares. They are two in number. Its main function is olfaction or sense of smell.

Hence, the correct answer is option (D)

Note: The gills of hermit crabs are adapted for respiration on land provided they are moist. Gills are also present in insect larvae, tadpoles, worms, molluscs, crustaceans. The gills have large surface area so that they can absorb the dissolved oxygen which is present in water. The gills are red in colour due to the presence of blood vessels.