Giant Otter Fact File


The giant otter is the longest of the otter species but shares a similar weight with the sea otter. Male giant otters can attain a length of 1.5-1.7m (4.9-5.6ft). Females are smaller at 1-1.5m (3.3-4.9ft). Their long tail may add as much as 70cm (28in) to this body length. An average giant otter will weigh between 22 and 32kg (49-71lbs).

Giant otter fur is the shortest of all the otter species. This fur is densely packed so that no water can penetrate through to the skin. They have an inner coat which is surrounded by guard hairs that keep the water off their actual coat.

The fur is coloured brown in most specimens though it can be fawn or red in some. On the throat is an assortment of white patterns. These patterns are different on each other and help them to distinguish each other in the group. They have small rounded ears which can close underwater.

The legs are stubby and short. At the end the feet are webbed and also have sharp claws.


Each day the giant otter consumes between 3 and 4 kilograms (6-9lbs) of food. A major portion of this diet will consist of fish. They also feed upon crustaceans, snakes, small caimans and anacondas. Their diet varies throughout the year due to the migrations of the fish.

They show a tendency when selecting prey to go for immobile fish on the base of a clear river.

giant otter

Scientific Name

Pteronura brasiliensis

Conservation Status



22-32kg (49-71lbs)



1.5-1.7m (4.9-6.5ft)


1-1.5m (3.3-4.9ft)


Wild 12 years

Captive 21 years



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Giant otters are native to South America. Countries where giant otters live include Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Peru, Suriname and Venezuela. Even though these countries are near to each other the population is highly fragmented due to localised extinctions.


These animals make their home in freshwater rivers and streams. Most of these flood throughout the year. Most of the time this species will chose the clear, sandy or rocky bottomed rivers over those that are salty, saline and white. Preferred habitats include riverbank high forests, floodable mixed marsh and high swamp forest, floodable low marsh forest and an open area within the creek.


Births can occur year round in giant otter colonies. There is evidence that long time pair bonds form. The male was always seen as the one who initiated the mating. These mating’s frequently took place in the water. They have an oestrous cycle lasting 21 days with mating taking place in the 3rd to 10th day of this cycle.

65-70 days after mating takes place one to five pups may be born. Twins are the most common occurrence though. The birth takes place in an underground den. This is located near a river and their fishing sites. These babies are furred but blind.

The entire group plays a part in raising the pups. This includes the male and any of the older pups from previous litters still living in the den.

When they are 4 weeks old the pups eyes open. A week later they begin to walk around and at 12 to 14 weeks they are swimming regularly. They lose their dependence on milk at 9 months of age and it is at this time they begin learning to hunt.

At 2 years old they are sexually mature. Most pups will leave the group a year later and go form their own pair.

giant otter


When on land giant otters come under threat from jaguars. In the water anacondas or caimans may attack this species. Young otters can come under threat from some other species. Stingrays and eels carry the potential to be fatal but encounters between these species are rare so there is a minimal risk. Piranhas can also take a good bite from a giant otter.

Giant otters are incredibly social. Their groups include 2 to 20 members but average 3-8. These otters work together when playing, travelling, feeding and sleeping together.

A range of vocalisations are demonstrated by the giant otter. 9 distinct sounds have been identified being made by this species. A newborn pup makes squeaks to gain attention.

This species maintains a den which they dig under fallen logs or into a river bank. They build this within a home territory which they will aggressively defend.

Giant otters wake up during the day making them diurnal.

Quick facts

Giant otters are members of the weasel family.

This species is the largest member of the otter family.

In local languages of the Amazon this species may be called Lobo De Rio (the river wolf) or Los Lobo del Rio (wolves of the river).

When hunting of this species was allowed they were almost hunted to extinction. They were hunted mostly for their pelts.

Photo Credits


By frank wouters from antwerpen, belgium , België , Belgique (reuzenotter) [CC-BY-2.0 (], via Wikimedia Commons


By Eric Gaba (Sting – fr:Sting) (Own work) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons


Groenendijk, J., Duplaix, N., Marmontel, M., Van Damme, P. & Schenck, C. 2015. Pteronura brasiliensis. The IUCN Red List of Threatened Species 2015: e.T18711A21938411. Downloaded on 15 May 2020.

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