how many species of river dolphin are there
River dolphin Four families of river dolphins (Iniidae, Pontoporiidae, Lipotidae and Platanistidae) are currently recognized, comprising three superfamilies (Inioidea, Lipotoidea and Platanistoidea). Platanistidae, containing the two subspecies of South Asian river dolphin, is the only accepted family of Platanistoidea.[1] Previously, many taxonomists had assigned all river dolphins to a single family, Platanistidae, and treated the Ganges and Indus River dolphins as separate species. A December 2006 survey found no members of Lipotes vexillifer (commonly known as the baiji, or Chinese river dolphin) and declared the species functionally extinct. With their disappearance, one of the recently accepted superfamilies, Lipotoidea, has become extinct.[2]
North American river otter The North American river otter (Lontra canadensis), also known as the northern river otter or the common otter, is a semiaquatic mammal endemic to the North American continent found in and along its waterways and coasts. An adult river otter can weigh between 5.0 and 14 kg (11.0 and 30.9 lb). The river otter is protected and insulated by a thick, water-repellent coat of fur.