Correct Option
The correct option is (a).
Explanation
The Gangetic River Dolphin (Platanista gangetica), designated as the National Aquatic Animal of India, is a freshwater cetacean found in the Ganga and Brahmaputra river systems. It is an endangered species protected under Schedule I of the Wildlife Protection Act, 1972.Statement-wise Analysis
- Statement 1 is Correct: The Gangetic River Dolphin is locally known as 'Susu' due to the sound it produces when breathing. It is also referred to as the "blind dolphin" because its eyes lack a lens, rendering it effectively blind. It relies entirely on echolocation to navigate and hunt in the turbid waters of the river.
- Statement 2 is Incorrect: The presence of the Gangetic River Dolphin is an indicator of the health of the river ecosystem. Since these dolphins require specific ecological conditions to survive, their presence suggests that the river water is relatively clean and the ecosystem is functional, rather than indicating high pollution.
- Statement 3 is Incorrect: The species is highly sensitive to habitat degradation. Untreated industrial chemicals, agricultural runoff, and pollution are major threats to its survival. It does not thrive in polluted waters; conversely, high pollution levels lead to a decline in its population.
Key Takeaway: The Gangetic River Dolphin is a blind freshwater mammal that uses echolocation. It acts as an indicator species for the health of the river; its presence signifies a healthy ecosystem, whereas pollution poses a severe threat to its existence.