The Ganges river dolphin lives in water that is so thick with mud it cannot see more than a few inches in front of it. River dolphins are blind, in fact their eyes don’t even have lenses in them. The dolphins finds their way around by making a series of clicking noises which, like radar, bounce off hard surfaces and these are perceived by the dolphins. River dolphins feed by pushing their flippers into the mud which stirs it up releasing crabs, bottom-living catfish and shrimps into the water. The dolphins also produce a rapid series of clicks during feeding to aid in locating these prey. Not sure if the dolphins look as contented in real life as they do in this picture.
Gouache in Moleskine sketchbook.