Scientific Classification
KINGDOM: Animalia
PHYLUM: Chordata
CLASS: Mammalia
ORDER: Carnivora
FAMILY: Mustelidae
GENUS: Pteronura
SPECIES: Pteronura brasiliensis
Conservation Status
The giant river otter is the longest of all otters and the largest member of the weasel family, which includes other animals like mink, ferrets, skunks, and the wolverine. They can reach lengths up to 6 feet long and weigh 75 pounds!
Giant river otters are perfectly equipped for an aquatic lifestyle with webbed feet, a long powerful tail, and a long streamlined body.
Their coat is a dark brown color with creamy white markings on their chest. They use these markings to help identify each other almost like a fingerprint and will display their chest out of the water when they meet, almost like a calling card so they know who is who. Their coat is extremely short but dense and velvety. It is so dense, in fact, that water does not reach their skin!
They also have ears and nostrils that close up when they submerge themselves much like a hippopotamus. Like all otters, they have a short, stubby face and are carnivores with a very powerful bite. The sagittal crest on their skull is where large powerful jaw muscles are attached.
Giant otters live in rivers and lakes in several areas throughout the Amazon basin.
They prefer a variety of different habitats but will go to any rivers with an abundance of food and proper denning areas. Anywhere with seasonally flooded marsh forests, rivers. and streams with clear water and rocky bottoms vs. silty or sandy bottoms is also sought out.
Giant otters will clear large amounts of vegetation along river banks for campsites, communal latrines and dens for pups. These areas can include tunnels that have many entrances and exits.
Giant otters have been driven from 80% of their original range, but they currently still live in Bolivia, Brazil, Colombia, Ecuador, Paraguay, Peru, Guyana, French Guiana, Suriname, and Venezuela. Some scientists agree the best otter habitat is in French Guiana and Guyana and represents the brightest future for the species.
Giant otters are apex carnivores and prey mainly on fish. Scientists discovered that 97% of their diet is fish. This even includes piranha. If fish are not around, they will eat small snakes including young anacondas, turtles, frogs, and even small caiman.
Although they will eat together and hunt together, they rarely cooperate like lions to bring down a single prey item. It is more akin to them all chasing down their own fish and eating it all together. It is only when the prey is larger or is threatening do they band together to bring it down.
When they eat, they grasp food with their front paws and will eat it head first. Young otters learn this important skill early on especially when your food can bite back like the piranha!
Giant otters have to eat anywhere from five to nine pounds of food everyday to maintain their body weight and energy levels. Imagine how much weight you would gain if you ate that much!
They are diurnal, which means they hunt by day and sleep at night. When they do hunt, they rely primarily on eyesight and will stick to areas where they can spot fish in relatively shallow water; usually about two feet deep on average. Scientists also notice they stick to slower and more clumsy fish species and catfish as their main prey.
When they are chasing fish underwater, their extremely sensitive whiskers help them sense pressure fluctuations in the water so they can chase down fish.
Giant otters breed all year-round but most pups are born in the dry season when the water levels in the lakes and rivers are lower and the fish population is at its most dense. They give birth on land and will dig dens in sandy riverbanks usually around tree roots.
When it comes time to mate, the males usually make the advances and will copulate in the water.
Their gestation period is around 70 days and the mother will give birth to two blind, helpless pups that are raised in the den. Both the male and female will help rear the pups during their most vulnerable period in the first week or two. But as the pups grow, the older their brothers and sisters will pitch in and everyone brings them fish, protects them, and plays with them.
They are very protective of their young and will defend them fiercely from predators.
The pups will open their eyes in about one month, are able to walk around a week later, and can swim confidently in three months. The juveniles will stay with the family for about two years and then venture out on their own and start their own family.
To giant otters, family is everything. They are the most social of all otter species and live in extended family groups centered around a breeding pair. It would be like you living with your mom and dad and many older brothers and sisters. They are very closely bonded and will eat, sleep, travel together, and fiercely defend each other during dangerous encounters.
Giant otters are the most vocal of all otters too. Researchers recorded as many as 22 different vocalizations in adults and around 11 in juveniles. Their loud and almost comical voices help them stick together and keep track of each other during their daily escapades in the thick forest. Young otters will engage in babbling sounds much like human infants, which helps them develop more complicated communication as they grow.
Giant otters are very curious and inquisitive. They will regularly swim up to boats to investigate visitors. This is because they are apex predators with no natural enemies except humans. Their family groups and large size makes them formidable opponents to other large predators like caiman and even jaguars.
