While visiting an aquarium, Aman noticed that fishes open and close their mouths and gill slits frequently. This action forces the surrounding water to enter their body.
Which of the following statements justifies the observation made by Aman?
The amount of dissolved oxygen in water is low
The amount of dissolved oxygen in water is low when compared to that of the amount of oxygen in air. Hence, the rate of breathing in aquatic animals is greater. Fishes open and close their mouths frequently, thereby forcing the surrounding water to enter their body. The dissolved oxygen is absorbed for breathing when the water passes through the gills.