GIANT OTTER: CHARACTERISTICS, FEEDING, REPRODUCTION - BIOLOGY - 2025

The giant otter (Pteronura brasiliensis) is a semi-aquatic mammal belonging to the Mustelidae family. Because much of your time is spent in rivers and lakes, your body has structures adapted to the freshwater ecosystem.

For swimming, this species uses its webbed feet with webbing like paddles. The characteristics of its coat make it impervious to water. The giant otter lives in the wetland forests of South America, from where it has become extinct in several regions due to the fragmentation of its habitat and indiscriminate hunting. The decrease in population has led the IUCN to categorize Pteronura brasiliensis as an animal in danger of extinction.

Source: Eric Gaba (Sting - fr: Sting), from Wikimedia Commons

The giant otter is very active during the day. You can communicate with the other members of your group through olfactory and vocal cues. To delimit the territory, it uses the smells emanating from the communal latrines.

The vocal signals are calls emitted by the giant otter, which allow it to communicate various situations. Due to the large number of vocalizations it can emit, it is recognized as the most vocal species among all otters.

Behavior

The giant otter is territorial, can live up to five years in the same habitat. It is very sociable, being able to live in groups of up to 10 relatives.

The family is usually represented by a male and a female, who form a couple, and by their offspring, made up of the offspring and one or more youngsters who were born in the previous 2 years.

The giant otter is an animal with a cohesive behavior, they can also share roles within the group without any kind of dispute. Although they are very peaceful animals, in the presence of a predator, adult males could unite and attack it aggressively.

A common behavior of the Pteronura brasiliensis is the body posture known as "periscope", which it assumes both outside and in the water. It consists of the animal stretching its neck, thus trying to locate prey or a possible predator with its smell or sight.

General characteristics

Face

It has a total of 36 teeth, in some species the lower premolar is absent. Their eyes are small and the iris is greenish-yellow.

The head of the giant otter is broad, supported by a long, muscular neck. The muzzle is sloping and blunt, from which numerous facial vibrissae protrude. The nose is completely covered with skin.

The giant otter is the only one, within its genus, whose shape of the tip of the nose varies between species. The nostrils, located towards the front upper part of the head, and the small, rounded ears can be closed to prevent the entry of water while the animal is submerged.

Tail

The tail of Pteronura brasiliensis is hairy, rounded and flattened dorsoventrally, much like a sword. This is how its name comes from, since Pteronura is a Greek word that means "sword-shaped tail."

The size is approximately 70 centimeters and it has a strong and thick musculature at the base that allows it to be used in the water as a rudder.

Extremities

Its limbs are sturdy and short. The legs are webbed and large. They have five fingers, with black interdigital webs, which end in very sharp and strong claws.

Fur

The shades of the coat can be from light brown to dark brown, going through reddish colors. Also, some giant otters could be gray.

The chest and throat area usually have irregular white or light beige spots. They are sometimes used to identify members of the same species. In very few cases, animals of this species have been found lacking these marks.

Giant otters use their spots to recognize each other. When meeting other otters of their species, they perform a behavior known as "periscoping", which consists of showing their white throats between them.

The coat of the Pteronura brasiliensis is velvety and dense, made up of short, waterproof protective hairs that trap water, keeping the undercoat dry. They also have guard hairs, which are around 8mm in length.

The velvety characteristic of its fur makes it highly sought after by fur traders, hunting this animal indiscriminately.

Size

Considering the thirteen species of otters that exist worldwide, the body of the Pteronura brasiliensis is the longest. Males are between 1.5 and 1.7 meters tall and weigh 26 to 32 kilograms. The females are 1 to 1.5 meters long, weighing between 22 and 26 kilograms.

The senses

This animal has a highly developed sense of sight. This benefits it when hunting its prey, which can be seen up to 50 meters away. They also have good hearing and excellent smell.

The sense of touch is specialized in their facial vibrisas, which are hard and erect hairs found on the snout.

In the giant otter these structures allow it to capture the variations of currents and water pressure. In this way they can detect their prey when they move in the water.

Vocalizations

The Pteronura brasiliensis is a mammal that has a wide range of vocalizations. All species of otter produce sounds, but because of their volume and frequency, the giant otter may be the most vocal of all.

22 different sounds have been identified in adults and 11 in newborns, with possible specific differentiations, depending on the context in which they are emitted. Sudden snorts or rapid barks are associated with an alarm or emergency situation.

A hesitant yell can be used against intruders, while a low one is a warning. To achieve a calming effect on the group she hums. The whistles are a warning, with a non-hostile intention between the groups.

Danger of extinction

The giant otter is categorized in danger of extinction by the IUCN, because its population is decreasing alarmingly. This is mainly due to the fragmentation of their natural habitat and illegal hunting.

The territory where the Pteronura brasiliensis inhabits is rapidly degrading and destroying. If this situation continues, it is estimated that within 20 years the population will have decreased by 50%.

Since times past, these animals were hunted to market their fur. The fact that this population emits several vocalizations, that it is active during the day and that it is not afraid to approach the human, has greatly facilitated its capture.

The regions of South America where the giant otter lives are being destroyed by mining, logging, oil exploitation and the construction of hydroelectric dams.

Also the land and rivers are polluted. This, coupled with excessive fishing, results in Pteronura brasiliensis affecting its diet, due to the depletion of local fish.

Actions

The vast majority of actions revolve around local efforts, with the intention of raising awareness about the need to protect this animal. These are reinforced with regional programs, articulated with national and international initiatives.

In the countries where the giant otter inhabits, its hunting is prohibited by law. An example of this happens in Chile, where the Agricultural and Livestock Service is one of the agencies in charge of enforcing the hunting law.

Another action is the creation of shelters, where this species is out of reach of the elements that influence its normal development.

In 2004, Peru established one of the largest protected areas in the world, the Alto Purús National Park. Another area is the Añangu refuge, located on the banks of the Napo River. This belongs to the Yasuní National Park, located in the Kichwa Añangu community, in Ecuador.

The effort of the Añangu Community to protect the giant otter has seen its fruits recently; three specimens of this emblematic species of the region were born.

Taxonomy

• Animal Kingdom.
• Subkingdom Bilateria.
• Chordate Phylum.
• Vertebrate Subfilum.
• Tetrapoda superclass.
• Mammal class.
• Subclass Theria.
• Order Carnivora.
• Suborder Caniformia.
• Mustelidae family.
• Subfamily Lutrinae.

Genus Pteronura

Species

Distribution and habitat

The Pteronura brasiliensis is a semi-aquatic species endemic to the wetlands and humid forests of South America. Historically these animals ranged throughout the lowland rainforests of South America.

Currently only remaining populations remain in Peru, Guyana, Paraguay, Venezuela, French Guiana, Bolivia, Suriname, Colombia, Brazil and Ecuador. In Uruguay and Argentina the species is probably extinct.

The giant otter is distributed in the main river systems of South America, from the Guianas to Uruguay, with elevations of up to 1,000 m. In Brazil there are isolated populations in the Amazon basin and the Jauapei River. In Bolivia they are only found in national parks.

Colombia, Suriname, and Guyana have the largest populations. P. brasiliensis is usually found east of the Andes, in the zone corresponding to the countries of Ecuador and Peru.

In Paraguay, they inhabited the Prana and Paraguay rivers. There are small populations in the protected areas of French Guiana and Venezuela.

Habitat

The Pteronura brasiliensis prefers areas where there are rivers with slow water movements and abundant fish. The groups could stay in the same area for more than 5 years, although they could also leave it at the time of the floods.

The giant otter frequents lowland freshwater streams, rivers, swamps and lakes in tropical forests. These clear, shallow waters make hunting easier, because Pteronura brasiliensis can better visualize its prey.

Thus, the giant otter prefers clear waters with sandy or rocky bottoms over silty, white and saline waters.

In some regions where the water has a high sediment load, otters choose those lakes where the residues of decomposition are deposited on the ground.

There are two important factors in habitat selection. The first is related to the abundance of food, and the other refers to the fact that these spaces should have a low slope, good coverage and easy access to bodies of water.

Camps

Around bodies of water, giant otters establish camping areas and areas for latrines.

In the camps they groom themselves, play, rest and have their young. To build them, these animals clean the vegetation on the ground, marking the area with secretions from the scent glands, feces, and urine. These areas are usually close to feeding areas.

Community latrines are located to one side of the camps, under fallen trees and root systems.

Feeding

The giant otter is a piscivorous carnivore that is usually opportunistic, taking those species that are more abundant. If fish are scarce, they can consume mollusks, crustaceans, and land vertebrates, such as snakes and small birds.

Among the most frequent prey are the Erythrinidae, Perciformes, Cichlidae, Characiformes, Anostomidae, Ctenolucidae, Osteoglossidae, Cynodontidae, Curimatidae, Pimelodidae, Myrenidae and Serrasalmidae

Daily, an adult female can consume about 2.29 kilograms and a young male about 1.52 kg. Due to their high rate of metabolism and rapid digestion, giant otters spend much of their time hunting.

Foraging generally occurs in water. They can hunt individually, in pairs or in groups. When the prey cannot be captured by a single otter, as could be the case with the juvenile black caiman and the anaconda, they group together, conducting cooperative fishing.

To catch its prey, the giant otter is very fast, performing turns and lunges. It can attack from below or from above, turning to hold its prey with its jaws. They use their front legs to grab the animal and immediately begin to consume it.

Reproduction

Females could have their first estrous cycle at 2.5 years, exhibiting some external indicators, such as enlargement of their four nipples and some behavioral changes.

Some of these could be aggressiveness and the struggle to assume the leadership position in the group. At two and a half years, males develop their testicles, thus initiating their reproductive stage.

Giant otters are monogamous. In the groups there is a dominant female, when this dies a close relative will take command, for example one of the female descendants who is already an adult. The care of the young is alloparental, which includes the care of the males.

All members of the family collaborate in the upbringing, participating in the cleaning, defense and feeding of the young people in the group.

Mating

The breeding season begins in late spring and early summer, although some species can breed throughout the year. The estrous cycle of the females lasts around 21 days, being receptive from 3 to 10 days of this cycle.

The couple may exhibit rough play and chasing before copulation. This act could be repeated several times in a day. Fertilization occurs in water, although it could happen on land.

Once the egg has been fertilized, the gestation process lasts between 65 and 70 days. On average, the female can give birth to 2 young, although the litter could be between 1 and 5 young.

When it's time to give birth, the Pteronura brasiliensis heads for the burrow it built. These are caves dug into the banks of rivers. They have several entrances and its interior is divided by several chambers.

The babies

At birth, the young otter weighs approximately 170-230 grams. They open their eyes at one month and two weeks old, the young can swim and float, but keeping their tail in the air and with a shallow level dive.

When they are between six and eight weeks old, they swim independently. The female stops feeding the young when it is between 4 and 9 months old.

References

1. Wikipedia (2018). Giant otters. Recovered from en.wikipedia.org.
2. IUCN Otter Specialist Group (2015). Pteronura brasiliensis (Gmelin, 1788), the Giant Otter. Recovered from otterspecialistgroup.org.
3. Duplaix, CJ Heap, T. Schmidt, T. Schikora, J. Carvalho, I. Rubiano, D. Ialeggio, S. Rivera (2015). Summary of Husbandry Guidelines For Giant Otters (Pteronura brasiliensis) In Zoos, Aquariums, & Wildlife Sanctuaries. Recovered from otterspecialistgroup.org.
4. Bender, J. (2001). Pteronura brasiliensis. Animal Diversity Web. Recovered from animaldiversity.org.
5. .Ministry of Environment and Sustainable Development- Colombia (2016). Management plan for the conservation of otters (Lontra longicaudis and Pteronura brasiliensis) in Colombia. Recovered from minambiente.gov.co.
6. Agricultural and Livestock Service - Chile (2018). Forbidden hunting species. Recovered from sag.cl.
7. ITIS (2018). Pteronura brasiliensis. Recovered from itis. gov.