Question

Presence of Susu (also called blind dolphin) in Ganga – Brahmaputra river is an indication of _______
A. Wealth of river
B. Health of river
C. Water of river
D. Presence of gold in the river

Answer 1

Hint:These dolphins need freshwater habits to survive. They have been getting lesser in number with rising pollution. It is quite impossible that any living organism could indicate the presence of wealth in any area.

Complete answer:
The Ganges river dolphin was officially discovered in the year 1801. These dolphins were once found in the Ganges-Brahmaputra-Meghna and Karnaphuli-Sangu river systems of India, Bangladesh and Nepal. But it is now extinct from most of its early distribution areas. Even in the Ganges river system, their numbers have been going down due to the effects of pollution. We shall now take a look at which of the given options are correct-

A. The presence of the blind river dolphin does not show the wealth of the river. Although it could be taken as showing the ecological richness of the river, but not wealth in the general sense. So, this option is incorrect.

B. The presence of the blind river dolphin in the Ganga- Brahmaputra river indicates the health of the river. The dolphins only survive in clean freshwater habitat. So the presence of pollutants means that the number of dolphins have reduced drastically. So, this is the correct option.

C. The presence of the blind dolphins does not indicate the presence of water in the river. To begin with, if the water is absent, it wouldn't even be a river. So this option makes no sense and is incorrect.

D. Like the first option, the presence of the blind dolphins do not indicate the presence of any gold in the river. So, this is also an incorrect option.

Therefore, the correct answer is Option B.

Note:The Susu are basically blind dolphins due to their extremely poor eyesight.
They hunt using the system of echo-location by emitting ultrasonic sounds.
They are usually found in small groups or alone.
The river dolphins have been declared an endangered species by the IUCN.