Inioidea

River dolphins also called Freshwater dolphins, are a polyphyletic group of fully aquatic mammals that reside exclusively in freshwater or even in brackish water. They are an informal grouping of dolphins, which itself is a paraphyletic group within the infraorder Cetacea. These dolphins are placed in three superfamilies, Platanistoidea (Platanistidae), Inioidea and Lipotoidea (Lipotidae). They comprise the families Platanistidae, the possibly extinct Lipotidae, Iniidae and Pontoporiidae. There are five extant species of river dolphins. River dolphins, alongside other cetaceans, belong to the clade Artiodactyla, with even-toed ungulates, and their closest living relatives the hippopotamuses, from which they diverged about 40 million years ago. Specific types of dolphins can be pink.