Despite all this, the dolphins have no sense of smell. Since dolphins belong to an intelligent group of animals, it is impossible for them to not communicate. The familiar marine dolphins, that seem to keep a permanent smile on their face, are very vocal, they chatter like a cricket, emit wonderful sounds that spread joviality in the air accompanied with frequent, vigorous, hopping and jumping in the water. Underwater recording has, so far, revealed no sing-song pattern of sound waves in blind dolphins that suggest their using a language. But the echo-location waves are very powerful, which could also transmit communicative signals that can be interpreted by other members as a message in code or ultrasonic language blind dolphins have as we understand a human kind of language.
Blind dolphins communicate on wavelength that are yet to be discovered and interpreted.
The blind dolphin of the Indus River was being killed for its 'fat' but recently due to the persistent protest by environmentalists, fortunately, the killing has been prevented and now they are fully protected. The killing of the Amazon dolphin was stopped not because of the fear of its extinction, but because the locals found out that its oil, used in oil lamps, could cause blindness. The Ganges is one of the most polluted rivers of the world, but it has some cleaner pockets where its dolphins can survive. As for the Indus dolphin, it faces a greater threat because of persistent drop in the water level. Due to the persistent silt in the river that has obstructed their sight, their eyes are of no use.