DOLPHINS OF RIVER BRAHMAPUTRA

Dolphins of Brahmaputra the river that originate from Himalaya . this non other than the gangetic river dolphin. the river dolphin grows to a maximum length of 8 feet. weighting about 100 kg. it has an elongated beak with about 28 sharp curved teeth on both its upper and lower jaw. it flippers are broad and ressembles paddles while the dorsal fin is short yet sturdy since the dolphin breaths through its nose and has to surface once every 30-50 seconds.

it reaches maturity at an age of 6 to 7 years and live upto 35 years. because of its poor eyesight the river dolphins can not be trained like the marine dolphin. and its age age span shortens considerably in captivity thus it can not be kept for shows in dolphinariums.

this dolphins uniqueness lies in its highly developed sonar sense. the species evolved over a millenia in the subcontinent rivers[ Brahmaputra Ganga an Indus] which are laden with silt. the silt make the water of these rivers murky with non zero visibility thus the river dolphin gradually lost the use of its eyesight but it's sense of hearing become hightended. it is the only aquatic mammal which has developed its sonar sense to such an extent that is captures it's prey and navigates with the help of ecolocation. 

several account of travelers from the 19th century describes the vast herds of river dolphins. that were regularly seen across the brahmaputra.  Unfortunately today their numbers were declined considerably due to  gillnetting poaching and damming.  A 2008 survey by the NGO Aranyak found only 264 dolphins along a 1031 km long stretch of the river.