Amazon River Dolphin
Rio Negro, Anavilhanas National Park, Novo Airão, Amazonas, Brazil
Inhabiting the river basins of Amazon and Orinoco in South America, the also called Pink river dolphin or "Boto" is the largest of the river dolphins species. Its pink color is due to a combination of factors such as repeated abrasion of the skin and scar tissue from social interactions, changes in blood flow and aging. Thus, adult males tend to be more pink, while newborns and young individuals are gray.