High Quality Content by WIKIPEDIA articles! The Amazon river dolphin, alternatively Bufeo, Bufeo Colorado, Boto Cor de Rosa, Boutu, Nay, Tonina, or Pink Dolphin (Inia geoffrensis), is a freshwater river dolphin endemic to the Orinoco, Amazon and Araguaia/Tocantins River systems of Brazil, Bolivia, Peru, Ecuador, Colombia and Venezuela. The species is one of a handful of oceanic and river dolphins included in a paraphyletic clade known as the botos, and is the largest of the river dolphins. Because they are unfused, the neck vertebrae of the Amazon river dolphin are able to turn 180 degrees. The pink dolphin lives in the freshwater of the Amazon River. This species looks like the grey dolphin, but individuals are bigger, and, instead of a dorsal fin, they have a hump on their back. Their tails are also bigger. The pink dolphin has been listed as endangered by the International Union for Conservation of the Nature due to pollution, overfishing, excessive boat trafficking and habitat loss. The brain of the river dolphin is 40% larger than a human brain.