Giant Otter: The Most Charismatic Mammal of South America

The giant otter (Pteronura brasiliensis) is a fascinating aquatic mammal native to South America. With its long body and flattened tail, it lives in tropical rivers and wetlands. It is the largest mustelid in the world, reaching up to almost 1.8 meters in length, yet despite its size, it is very agile in the water. Unlike most otters, the giant otter is extremely social: it lives in families of 3 to 8 individuals with a dominant breeding pair. These groups cooperate to hunt fish and defend their territory, communicating with loud vocalizations (it is the most “talkative” otter). Watching giant otters hunt and play is one of the most exciting moments of a photo safari in Brazil’s Pantanal. That’s why this species sparks interest in travelers from all over the world, who book ecotourism tours in Brazil to observe it in its natural habitat.

What are the characteristics and behaviors of the giant otter?

Scientific name and physical appearance

The giant otter belongs to the Mustelidae family and its scientific name is Pteronura brasiliensis. Its fur is dense and brown to dark, with irregular white markings on the throat and chest, unique to each individual. These markings allow for individual identification within the group. It also has a flattened wing-shaped tail and webbed feet—adaptations that help it swim efficiently.

Size and weight

Adult males measure between 1.5 and 1.8 meters (including the tail) and weigh between 26 and 32 kg; females are 1.5 to 1.7 meters long and weigh 22 to 26 kg. Its neck is muscular and its head is broad with long whiskers that detect water currents. Despite its large size, the giant otter swims fast and can dive for long periods.

Habits and social behavior

The giant otter is very social: it lives in tight-knit family groups of 3 to 8 individuals, with a dominant pair and their offspring. They cooperate in hunting, playing, and caring for the young. They are diurnal, active during the day, and highly vocal, producing a range of sounds (shouts, growls, whistles) to communicate.

Diet and feeding habits

The giant otter is a top predator. Its diet is almost exclusively piscivorous, including piranhas and catfish. It may also eat crabs, turtles, and snakes. It hunts cooperatively: one otter chases the prey while others are ready to assist from nearby.

Life cycle and reproduction

They live in burrows dug into riverbanks. Females give birth to 1 to 5 pups per litter (2 is most common). Pups are born fully furred but with eyes closed. They learn to swim at 3 months and are weaned by 1 year old. They reach sexual maturity around age 2. In the wild, they live up to 10–12 years.

Where does the giant otter live?

Natural habitat and distribution

The giant otter lives only in South America, in parts of Bolivia, Brazil, Colombia, Ecuador, the Guianas, Paraguay, Peru, Suriname, and Venezuela. It is extinct in Argentina and Uruguay. In Brazil, it is mostly found in the Pantanal and northern Amazon.

Aquatic ecosystems

It prefers slow-moving freshwater: rivers, lagoons, and marshes. During the dry season, they concentrate in shrinking watercourses, making them easier to observe. In these areas, they build dens and muddy slides to dive into the water.

Giant otter in the Brazilian Pantanal

The Pantanal is one of the best places in the world to see giant otters. In areas such as Cuiabá and Porto Jofre, especially between July and September, it's common to spot otter families at sunrise or sunset.

15 Curious and surprising facts about the giant otter

1. World’s largest otter: up to 1.8 meters long.
2. Social and cooperative: lives in family groups that hunt and raise young together.
3. Very noisy: has more than 20 types of vocalizations.
4. Unique throat markings: like a “fingerprint” for each individual.
5. No natural predators: only humans pose a threat.
6. Dens and slides: creates muddy slides to dive into water.
7. Expert swimmer: can stay submerged for up to 6 minutes; very agile.
8. Fast in water: can reach up to 12 km/h.
9. Almost 100% piscivorous: mainly freshwater bony fish.
10. Local names: ariranha, river wolf, water jaguar.
11. Ecological indicator: presence reflects healthy river systems.
12. Endangered: only 1,000–5,000 individuals left in the wild.
13. Cooperative breeding: all group members help raise the pups.
14. Active during the day: ideal for observation and photography.
15. Longevity: up to 19 years in captivity.

Ecological importance and conservation of the giant otter

The giant otter plays a key role in the ecosystem: it controls fish populations and signals healthy rivers. It is a conservation symbol and a driver of responsible ecotourism. Despite legal protection, it is seriously threatened by agriculture, dams, pollution, and fishing. Conserving it also helps protect the Pantanal and the Amazon.

Best places to see giant otters in Brazil and South America

1. Brazilian Pantanal: in Mato Grosso, especially Porto Jofre and Poconé (Cuiabá River). Dry season (July–September).
2. Amazon regions of Brazil and Peru: Jaú National Park, Mamirauá Reserve, Manu, Tambopata.
3. Llanos of Venezuela and Colombia: less touristy, but with confirmed presence.
4. Other countries: Guyana, Suriname, French Guiana, Paraguay, Bolivia.

Lorenzo Expeditions organizes photo safaris in the Pantanal, with expert guides and boat rides along the Cuiabá River during optimal seasons to photograph giant otters and other wildlife.

Tips for photographing the giant otter in the wild

1. Long telephoto lens (300 mm or more) and light tripod.
2. Best light: sunrise/sunset during the dry season.
3. Stay quiet and patient in the boat.
4. Low angle at water level.
5. High shutter speed (at least 1/1000 s).
6. No flash: use only natural light.
7. Specialized guided tours (like those from Lorenzo Expeditions) improve your chances.

Frequently Asked Questions About the Giant Otter

1. How big and how much does the giant otter weigh?

Males can reach up to 1.8 meters in length and weigh around 30 kilograms, while females measure between 1.5 and 1.7 meters and weigh between 22 and 26 kilograms. These dimensions make the giant otter the largest semi-aquatic mammal in South America.

2. What does the giant otter eat?

The giant otter's diet consists mainly of river fish such as piranhas and catfish. It also consumes crustaceans and small reptiles, reflecting its role as a key predator in aquatic ecosystems.

3. Where can the giant otter be observed?

It can be seen in places like the Brazilian Pantanal, especially in Porto Jofre and the Cuiabá River, as well as in the Peruvian and Brazilian Amazon, areas that provide its natural habitat and protection.

4. What time of day are they most active?

Giant otters are diurnal animals, being most active and visible early in the morning and at sunset, which are ideal times for those who want to observe their behavior in the wild.

5. Is the giant otter endangered?

Yes, the giant otter is classified as “endangered” due to habitat loss and human threats. There are only between 1,000 and 5,000 individuals left in the wild.

6. Is it dangerous to humans?

It does not pose a danger to people, but it can become aggressive to defend its young if it feels threatened or disturbed, so it’s recommended to keep a respectful distance.

7. What is the best time to see the giant otter in the Pantanal?

The dry season, from July to September, is the best time to see them, as the water level drops and animals gather in smaller areas, making sightings easier.

The giant otter is the largest mustelid in the world, reaching up to 1.8 meters in length with a highly social and cooperative behavior. It inhabits rivers and wetlands in South America, with the Pantanal and the Amazon standing out. Its diet is almost exclusively made up of fish. It is endangered and serves as a symbol of responsible ecotourism in Brazil and neighboring countries. Contact us and book your safari to the Brazilian Pantanal.

Tours Where You Can See the Giant Otter

• Pantanal Jaguar Safaris Brazil – 3 Days Camping
• Pantanal Jaguar Safaris Brazil – 4 Days Camping
• Pantanal Jaguar Safaris Brazil – 4 Days
• Pantanal Jaguar Safari – 5 Days
• Pantanal Jaguar Safaris – 6 Days
• Pantanal Jaguar Safaris – 8 Days (Photo Tour)