Giant Otters: Characteristics,habitats, behavior and more.

The giant  otters  are carnivorous amphibian mammals, that  belong to the Pteronura  genus. In fact are  the only otters of this  genus, and  are the longest member of the mustelid family to which  also belong the water wolves.

These South American otters ( Pteronura Brasiliensis) are the biggest in the world, reaching about 1.8 meters long. They live only in the rivers and streams of the Amazon, Orinoco and La Plata river systems. In addition, they are known as South American Otters and water dogs, names that are given in both the Spanish and Portuguese languages. In Brazil they also call them Arirai or Ariranha,  Wankanim in Ecuador, while the Yanomami located in Venezuela and Brazil call them Hadami.

They are very different from the rest of the otters, which make them be often considered as another type of animal. They are the largest otters in the world, and you should take advantage of this blog, to learn everything about his huge and interesting animal.

Giant Otters’ Main Characteristics

This species is the largest among all the species of otters in the world, (sea otters  , with their more compact body, can weigh considerably more). The males reach a total length of 1.5 to 1.8 m and a weight between 26 and 32 kg. As for females they usually measure 1.5 to 1.7 m in length and can weigh between 22 and 26 kg. It is usually difficult to distinguish between giant male and female otters, because there is no biggest difference between the shape of their head and the size of their bodies. Their tails have a length of approximately 70 centimeters. These otters have a short snout, an oval-looking head, and a pair of small, rounded ears. Their nose is completely covered with hairs, their legs are short and thick with webbed feet, and their claws are very sharp.


The Giant Otters have a short coat whose color may vary depending on the specimen. Some giant otters have light brown fur and others have a reddish hue. Their fur is very useful because it traps water, keeping the inner skin layer of these animals dry. Such fur has a width of 8mm and is twice as wide as the inner layer. The giant otters’ skin has a velvety appearance, and has a cream or white spot on the neck. Their nose is covered with hairs (excepting the nostrils), and has whiskers that are very sensitive to water pressure, which allows them to easily detect changes to locate their prey.

let’s watch them

Habitat and Distribution

This is an endemic species of South America and its populations are discontinuous and fragmented due to local extinctions. Its distribution range includes the basins of the Orinoco, Amazonas and Paraná rivers and Guyana’s hydrographic networks. Giant otters are also found in Bolivia, Brazil, Colombia, Ecuador, Peru and Venezuela, and are believed to have become extinct in Argentina and Uruguay. Years ago, they lived in tropical forests and wetlands, but the presence of human beings has drastically changed this situation. Their natural habitat  is characterized by the presence of slow-moving streams, lakes, rivers, and marshes, and are sometimes seen in agricultural channels and drainage channels along the roads.

What do Giant Otters Feed On?

These otters are considered as a Super Predator, which means that they are at the top of the food chain of their habitats. The status of this animal is an indication of the state of health of the ecosystem where they live.

Giant otters are opportunistic, since they adapt, and consume the available species from the place where they are. The captive specimens consume a percentage of food that goes around 10% of their body weight per day.


They mainly feed on fish like piranhas. In addition, according to studies that have been carried out about their feces, it has been concluded that they also consume sea bass, grouper, and goby among others which are frequently found in shallow water. The giant otters also eat to a lesser extent crabs, snakes, small alligators and anacondas of equal size.

giant otters : enjoying its prey

How the Giant Otters Hunt?

Giant otters can hunt alone or in pairs and even in groups. When they hunt in a group, it is mainly due to incidental factors. The real group hunting occurs when the prey is large, such as an alligator or an anaconda.

The Giant Otters rely on their sharp vision to locate food, and prefer to catch still fish that are in shallow waters. They chase their prey in a fast and scandalous manner, being characteristic of this the process the strong attacks and the turns in the water. In most cases hunting is successful. Giant otters attack either above or below the water holding the prey with their teeth strongly. Immediately after hunted they consume their prey, devouring it by the head and holding it with their front legs firmly.

here they are

Common Behavior the Giant Otters

Giant otters are very sociable creatures and live in family groups made up of three to ten individuals with well-established territories. These groups are composed of a dominant breeding pair, young non-breeding and their descendants. The family’s  members live, rest, play and fish together. They use community latrines where they discharge their waste and rub their feet with urine and feces with the aim of announcing their presence and reiterating their territorial limits.

These otters are noisy and according to different studies can produce 22 different sounds according to each situation. Among the most prominent vocalizations are those of warning, attention and lament.

Aggression and Defense

In the past, acts of aggression among the Giant Otters have been documented. Inter-species aggression is common among predators, but rare in mustelids. The presence of this behavior in the Giant Otter is due to complex social relationships, and the observations of the researchers indicate that these otters seek communication mechanisms to avoid conflicts.

The defense of these mammals against some intruders apparently is cooperative, and each one of the specimens has an important role for the care of their territories. The adult males are those that present the condition of aggressive defense, while the females on the other hand form vigilance groups.

Tests of the above mentioned were seen in the Great Brazilian Pantanal where several scientists observed three otters attacking a solitary specimen near a territorial limit. Otter carcasses have also been found with clear indications of attack by other otters, with their snouts and genital areas completely bitten. This behavior´s pattern has also been observed in captive otters.

Voice Communication

The giant otters are characterized by being very noisy. They have a complex and very complete repertoire of vocalizations. It is known that the extinct Japanese otters also performed vocalizations however not as complex as those of this species. Nine different sounds have been identified that have additional subdivisions that depend on the context in which they are communicating. A quick sound HAH! Similar to a bark, indicates that otters are on alert for possible nearby dangers. They can also use wavering cries in false attacks against intruders and often use a low-pitched grunt as a warning of an assault.

They can also make peaceful sounds for other families, and newborns usually cry out for their parents to pay attention to. When the young specimens begin to participate in group activities howl and groan.

Let´s listen to them

How Giant Otters Reproduce?

The breeding pairs of giant otters are monogamous, which means they have fixed partners throughout the year. They reach sexual maturity at 2.5 years of age, but begin to mate at 4.5 years.

Generally couples produce an annual litter, with a number of offspring ranging from one to six, but two births have also been recorded in the same year. The gestation period lasts between 64 and 77 days and both parents are responsible for care and feeding.

After 4 months of life, the small otters begin to make their first trips to learn to hunt. At six months they are weaned and at ten months they are already efficient hunters. The older males and siblings are actively involved in raising the puppies, which are born with their eyes closed and with hair all over their body. They open their eyes after four weeks of life, and begin to walk after the fifth week. Young otters swim properly between 12 and 14 weeks of age.

How long they live?

These mammals have a life expectancy of eight years in their natural state. When they are in captivity, the time is longer and they can reach up to 17 years. It is said that there is a record of 19 years, but it has not been confirmed. Various diseases can affect their life cycle as they are sensitive to the attack of some parasites, such as the flies’ larvae

Main Threats.

The adult giant otter has no natural enemies and the offspring are always under the watchful eye of adults. Even so, puppies are a bit vulnerable and can be devoured by jaguars, pumas and crocodiles. There are cases where anacondas and alligators include them in their diet, but they are not very common. Within the water the giant otters, both adult and pups , can be attacked by the stingrays (int) which are potentially deadly.

There is competition for food between this species and river otters , but apparently there is no conflict between them. They also compete with the Pink Dolphin for food however it is not of greater concern because of the different of their habitats. Humans represent the greatest danger that currently exists for Giant Otters, who by their sociable and curious behavior, easily approach humans, making them more vulnerable because they trade with their skin and are hunted unscrupulously.

let’s watch them

Giant Otters´ Hunting

From 1960 their hunting by humans became the main problem for the survival of the giant otters. It is known about statistics that indicate that between the years of 1959 and 1960 were captured between 1000 and 3000 specimens per year, only in the Brazilian Amazon to traffic with their skin. Their population was reduced in such a way, that in 1971 only was found and captured 12 specimens. In 1980 the skin of this animal had a cost of 250 dollars in the world market.

Destruction of Their habitat

In 1980 the hunting of the Giant Otter had been controlled a bit, since there were very few specimens in their natural state and their population was increasing little by little. Since then, hunting was not their biggest problem, but the destruction and degradation of their habitat by human factors.

In recent times, (2004) some investigations calculated that this species would face a decrease in its population that would reach 50% in the next 20 years, that is to say that in 2024 there will be half the population available that year. The invasion of its habitat is mainly due to the wood industry which affects the jungle vegetation on the banks of the rivers. Human activity has affected the distribution of the species, by isolating populations where reproductive age individuals find it more difficult to find pairs as well as new territories to form a family.

Mining affects the water available in its surroundings. We can mention the case of the gold industry which contaminates with mercury the fish that are part of the diet of these mammals. The extraction of fossil fuel also represents a danger for giant otters. Finally, there are the fishers who see them as a threat because they feed on the fish they want to fish.

Ecotourism is a double-edged sword, since it really helps to make people aware of the conservation of the species, but at the same time the methods they use, directly disturb their environment.


Colombian Aborigines

A study was conducted in five indigenous communities in Colombia, which showed that their attitude constitutes a risk for the species, because these aborigines see it with contempt and consider it harmful because they interfere with their fishing task.  For this reason these people usually kill them. They have been told about the importance of the species for the ecosystem and the danger of extinction in which the giant otters are, but they just have no interest whatsoever in living with the giant otter.

However, children of school age have a positive perception of this species.  It is only necessary to educate them correctly so that they do not have the same attitude as their parents.

Help for the Giant Otters

Not everything related to the human beings is bad for this species. There are people who are in charge of carrying out studies, and of creating and improving protected areas so that the population of this mammal increases. Let’s now know everything related to the help given to this animal.


Since 1999, this species is on the IUCN red list and has been considered a vulnerable species since 1982.  The CITES includes giant otters in Appendix I, which indicates that international trade in the species and products associated with it is prohibited.

As we mentioned earlier, ecotourism helps but also causes a problem for these otters. For this reason some researchers have proposed areas free of human presence where otters are only observed through distant towers and platforms, also suggesting limiting the number of tourists allowed at the same time, to provide proper protection for this animal.

The government of Peru created a conservation area, (the largest in the world) whose size is comparable to the size of Belgium. In this area there are different threatened animals and plants and among them are the giant otters. In Bolivia there are also specimens in protected areas, in spaces a little larger than Switzerland.

In a ranch located in Guyana called Karanambo, rehabilitation work is carried out for Orphan Giant Otters or who have been rescued from captivity.

The Story of Daniel

In August 28, a Swiss tourist who made bird watching in Nauta, Peru, alerted forest authorities about people transporting animals in a sack. The authorities rescued an otter and a lazy bear. «It’s a very sad situation. In general, to obtain a baby otter, the hunters massacre their entire family, «explained an official.

Forest authorities handed over the rescued otter to Rarec, which is a locally accredited entity to rehabilitate manatees and other Amazonian mammals. Daniel had no physical injuries but he was malnourished and scared. His caregivers had to feed him with special milk donated by the Pittsburgh Zoo, United States.

Today, Daniel is fully recovered; weighs 4.5 kilograms and consumes 600 grams of fish per day. According to Rarec, his favorite fish is the maparate but his caretakers try to give him a balanced diet by the time he returns to nature. The reincorporation of this nutria to the environment will be a complicated issue. Jairo Garnica (forest officer) points out that these animals usually live in herds of up to 12 individuals and if they release it alone, he could die. Therefore, Rarec will seek to gather more otters rescued from hunters to give a new family to Daniel.


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