Southern River Otter

A medium-sized otter, the southern river otter's body can grow up to 70 cm (28 in) long, with the tail adding about 40 cm (16 in). Body weight averages about 5–10 kg (11–22 lb). Its fur is dark brown on the upper parts and a lighter cinnamon color or can be almost white on the underside.

The southern river otter can be found in marine, freshwater, and terrestrial habitats, but are mostly found in freshwater lakes and rivers having a significant amount of dense vegetation, especially along the shorelines, which must be present to use as cover. Their habitats also need the root systems of mature trees, as well as fallen tree debris. Although referred to as a "river" (freshwater) otter, the southern river otter is equally adapted to venturing into more brackish (even fully marine) waters to forage and hunt. This trait is similar to the South American marine otter (L. felina), a nearly fully marine, coast-inhabiting otter.

Family groups usually consist only of a female and her young, as males are usually solitary except for the breeding season. Litter sizes average one to two pups, but up to four can be born at a time. They are piscivorous, and their natural prey includes many types of fish, crustaceans, mollusks, and occasionally birds or their eggs, particularly of ground-nesting species found near water. Occasional reptiles or amphibians may be hunted as well, including frogs, smaller turtles, lizards and even some snakes.

In Mapuche culture the southern river otter, or huillín, is associated with sexual prowess. Its fat is said to help loncos to satisfy their multiple wives.