Neotropical river otters are members of the family Mustelidae, which includes badgers, weasels, tayra, and wolverine. They are covered in a short, dark grayish-brown pelage with fur around the muzzle and throat being lighter in color. They possess a long wide tail, with short stout legs and fully webbed toes. These otters have small ears, short legs, and fully webbed toes. Their powerful jaws are well adapted for feeding on mollusks and crustaceans. Males in this species are usually larger than the females.
Neotropical river otters are found in Central America, South America and the island of Trinidad. Their habitat can range from northwest Mexico to central Argentina. These otters are found in many different riverine habitats, including deciduous and evergreen forests, savannas, Llanos, and Pantanal. They prefer clear and fast-flowing rivers and streams. Neotropical otters can inhabit formidable habitats such as wastewater treatment plants, rice and sugar cane plantations, drainage ditches, and swamps. They can inhabit cold, glacial lakes in the Andes of Ecuador. They can also live on the shorelines of marine environments hunting marine species and playing in the highly saline water.
Neotropical river otters are very shy and elusive animals that lead a solitary way of life. They are diurnal, but sometimes can be active after dark. These otters are very graceful and fast swimmers; they are often seen swimming with just the head popping above the water, or on occasion, basking at the water’s edge. Neotropical river otters live in dens on banks. They prefer dens near fresh water, high food availability, and relatively deep and wide water. Dens may have more than one opening, so the otter can easily exit to forage for food while staying safe from predators. They prefer to den in a cavity among stones or under tree roots. Vegetative cover is also very important. In comparison to other otter dens, the Neotropical otter dens do not have holes directly into the water, they do not use plant material as bedding, and will live in caves without light. These river otters communicate with each other via scent marking as well as whistles, hums, and screeches. They mark their territory with scratching or spraint (feces) in obvious places like around their dens, rocks and under bridges.
Little is known about the matin system in Neotropical river otters. Breeding occurs mostly in spring. The gestation period lasts around 56 days after which a litter of 1-5 pups is born. The pups are born blind yet fully furred. They will emerge from their mother's nest when about 52 days and begin swimming at 74 days. They are raised completely by their mother, as males do not provide any parental care. The male will only spend a single day with the female during the breeding season.
Heavy hunting for their fur in the 1950s-1970s resulted in much local extinction over Neotropical river otters' range. Illegal hunting, habitat destruction through mining and ranching, and water pollution still affect the population of this species. Neotropical river otters are threatened by habitat degradation associated with: agriculture, soil compaction, pollution, roadways, and runoff. Also, when forests are cleared for cattle grazing, heavy vegetation (which is the otter's preferred habitat) near streams is also cleared or trampled by cattle. This species is a very important ecological indicator because they prefer ecologically rich, aquatic habitats and have a low reproductive potential.
The IUCN Red List and other sources don’t provide the number of the Neotropical river otter total population size. Currently, this species is classified as Near Threatened (NT) on the IUCN Red List and its numbers today are decreasing.
Neotropical river otters are important predators of fish and aquatic invertebrates.