The giant river otter is classified as the largest of all otter speices! Because of constant flooding in Brazil, which causes the movement of giant river otters from one territory to another, it's also said to be the most adaptive (Pickles et al. 2011, Rosas et al. 2009). Look below for more information on the giant otters' adapted behaviors and traits.




Baby Pteronura brasiliensis on land. Image provided by Pete Oxford via Arkive.    The giant river otter lurks on land and water, recognizable with its abnormally small flat head but long sturdy body. This semi-aquatic organism has a brown fur coat that allows it to successfully and quickly move through the water to catch its prey. It also has a strong muscular tail that propels it through the water. The giant river otter may seem cute with its adorable rounded ears and webbed feet, which help it to swim effectively, but watch out because those webbed feet consist of retractable claws that aid in the catching and shredding of its prey (Rosas et al. 2009). Another species with similar characteristics to the Pternonura brasiliensis is the muskrat, with its webbed feet, strong tail, claws, thick fur to keep warm, and its marsh habitat! To learn more about the muskrat, visit this website.




Swimming giant river otter. Image provided by Christophe Courteau via Arkive.  Studies show that giant river otters can weigh a maximum of 30 kg, and their bodies grow no longer than 1.8 meters. Females are considered to be a little shorter than the males in otter populations, but the female otters weigh quite a bit more (Rosas et al. 2009). These numbers can vary based on which individuals and populations are tested. Such a great weight and length allow the giant otters to maintain body heat throughout the changing seasons and are used to show dominance against predators.





Giant river otter in the swamp. Image provided by Pete Oxford via Arkive.    South America experiences drastic changes in seasons, from wet to dry, which has caused the giant  river otter to adapt a behavior in response to this environmental stimulus. Otters build dens in the dry seasons, usually along rivers and ponds, in which the otters keep their cubs and sleep during the night. However, in the wet seasons, the giant otter abandons its den and treks across the land, moving from the riversides and ponds to the flooded forests and swamps. It is here that otters can more adequately catch their fish because swamps and forests have shallower waters. Although flooding prevents the ability to build dens, the otters have adapted the knowledge to build beds out of shrubs (Leuchtenberger et al. 2013).This constant movement, due to changing of seasons, led to the adaptations of an even cooler behavior as shown below!



River otter smelling the riverside. Image provided by Hermann Brehm via Arkive.Giant river otters have adapted the behavior of scent-marking. This behavior may seem gross to some, but it's actually quite fascinating and important to the survival of the giant otter as it moves to different territories. Scent-marking is a process by which the alpha males or females excrete urine or feces in a certain area in order to mark their territory, show their sexual maturity and availability, or show dominance over other predators (Leuchtenberger and Mourao 2009). Scent-marking takes many forms in which the giant otters can communicate with each other. This is how females find their mates and males protect their families against predators.




If you think the the adaptations of the giant river otters are interesting, just wait! Continue on to the next page to learn about their reproduction.






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