The Amazon River Dolphin (Inia geoffrensis), also known as the pink river dolphin or boto, is a species of toothed whale classified in the family Iniidae. Of the three currently recognized subspecies, the Bolivian river dolphin (I. g. boliviensis) is sometimes considered to be a separate species. It lives in the Amazon basin, the upper Madeira River in Bolivia, and the Orinoco basin.
The Amazon river dolphin is the largest species of river dolphin, with adult males reaching 408 lb in weight, and 8.2 ft in length. Adults acquire a pink color, more prominent in males, giving it its nickname "pink river dolphin". Sexual dimorphism is very evident, with males measuring 16% longer and weighing 55% more than females. Like other toothed whales, they have a melon, an organ that is used for bio sonar. The dorsal fin, although short in height, is regarded as long, and the pectoral fins are also large. The fin size, unfused vertebrae, and its relative size allow for improved maneuverability when navigating flooded forests and capturing prey.
They have one of the widest ranging diets among toothed whales, and feed on up to 53 different species of fish, such as croakers, catfish, tetras and piranhas. They also consume other animals such as river turtles and freshwater crabs.
In 2008, this species was ranked by the International Union for Conservation of Nature (IUCN) as being data deficient, due to the uncertainty regarding its population trends and the impact of threats. While hunting and pollution is a major threat, in recent decades greater impacts on population have been due to deforestation and other human activities that contribute to disrupt and alter their environment inadvertent entanglement in fishing lines. In 2018, the species was listed on the Red list of endangered species.