Ariranha, the Giant Otter (Pteronura brasiliensis) is a South American carnivorous mammal. The species prefers freshwater rivers and streams, which are usually seasonally flooded, and may also take to freshwater lakes and springs. It constructs extensive campsites close to feeding areas, clearing large amounts of vegetation and fish. The Ariranha is large, gregarious, and diurnal. Males are between 1.5 and 1.8 meters in length and females between 1.5 and 1.7 m. The animal’s well-muscled tail can account for as much as 70 cm of its total body length.