Giant otter
Longest mustelid, social, diurnal, endangered by poaching and habitat loss.
The giant otter or giant river otter (Pteronura brasiliensis) is a South American carnivorous mammal and the longest member of the weasel family, Mustelidae, reaching up to 1.8 m (5 ft 11 in). Atypical of mustelids, it is a social, diurnal species known for its loud vocalizations and amphibious adaptations.
- length
- up to 1.8 m (5 ft 11 in)
- weight_male
- 26–32 kg (57–71 lb)
- weight_female
- 22–26 kg (49–57 lb)
- range
- north-central South America, primarily Amazon River and Pantanal
- diet
- almost exclusively fish, also crabs, turtles, snakes, small caimans
- known_for
- longest mustelid, social behavior, dense fur, distinct vocalizations
Lore & Background
The giant otter ranges across north-central South America, living mostly in and along the Amazon River and in the Pantanal. Its distribution has been greatly reduced and is now discontinuous. The Guianas are one of the last strongholds, with modest numbers also in the Peruvian Amazonian basin. The species constructs extensive campsites close to feeding areas, clearing large amounts of vegetation. It subsists almost exclusively on fish, particularly characins and catfish, but may also eat crabs, turtles, snakes and small caimans. It has no serious natural predators other than humans, although it must compete with other predators such as Neotropical otters and various crocodilian species for food resources.
Reader's Guide
The giant otter is significant as the longest member of the weasel family and a rare example of a social, diurnal mustelid. Habitat degradation and loss are now the greatest current threats. Its unique vocalizations—documented for alarm, aggression, and reassurance—and adaptations such as webbed feet, a wing-like tail, and exceptionally dense fur highlight its specialization for an amphibious lifestyle. The giant otter's evolutionary divergence, estimated between 5 and 14 million years ago, places it as a distinct lineage within the otter subfamily.
Did You Know?
- The giant otter is the noisiest otter species, with distinct vocalizations for alarm, aggression, and reassurance.
- Its genus name Pteronura comes from Ancient Greek words for 'feather' or 'wing' and 'tail', referring to its wing-like tail.
- The species has the shortest fur of all otter species, but it is so dense that water cannot penetrate to the skin.
- In Brazil it is known as ariranha (from Tupi) or onça-d'água, meaning 'water jaguar'.
Frequently Asked Questions
What is the Giant Otter?
The Giant Otter (Pteronura brasiliensis) is a large, social carnivorous mammal native to South America. It holds the title of the longest member of the weasel family, Mustelidae, and is notably active during daylight hours rather than at night.
How big is the Giant Otter?
A fully grown individual can stretch to roughly 1.8 meters (about 5 ft 11 in) in total length. Males typically weigh between 26 and 32 kg, while females come in slightly lighter at 22 to 26 kg.
What does the Giant Otter eat?
Its diet is overwhelmingly fish-based, though it will also take crabs, turtles, snakes, and even small caimans when the opportunity arises. It is essentially a specialist predator of aquatic prey.
Where does the Giant Otter live?
You'll find it across north-central South America, with the Amazon River basin and the Pantanal wetlands serving as its core strongholds. It is an amphibious animal that spends significant time both in and out of the water.
Why is the Giant Otter endangered?
Poaching for its dense fur and the loss of riverine habitat are the two main threats pushing the species toward decline. Its social, family-group lifestyle also makes it especially vulnerable when a single member is targeted or its territory is disrupted.
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