Primates:
* Aye-aye (Daubentonia madagascariensis): This nocturnal lemur is found in Madagascar and is known for its unusual physical characteristics and its habit of tapping trees with its middle finger to locate grubs. While it lives near rivers, it is not considered a true river mammal.
Rodents:
* Capybara (Hydrochoerus hydrochaeris): This semi-aquatic rodent is the largest living rodent and is found in South America. They are excellent swimmers and often spend time in rivers, lakes, and marshes. They are not entirely aquatic but rely heavily on water for survival.
Carnivores:
* Otter (Lutra spp.): Several otter species, including river otters, are found in rivers worldwide. These sleek, semi-aquatic mustelids are excellent swimmers and divers, feeding primarily on fish and other aquatic animals.
* Sea Otter (Enhydra lutris): While these are often called "sea" otters, they are closely related to river otters and are sometimes found in rivers. They are particularly adapted to living in the ocean.
Cetaceans:
* River Dolphins (Platanistidae and Iniidae): Several species of river dolphins inhabit rivers in South America, Asia, and Africa. These dolphins are adapted to life in freshwater environments with limited visibility and often have unique adaptations like long, slender snouts and echolocation abilities.
Other:
* Manatees (Trichechidae): These large herbivorous mammals are found in rivers, estuaries, and coastal areas in the Americas. They are slow-moving and rely heavily on aquatic vegetation for food.
* Platypus (Ornithorhynchus anatinus): This unique egg-laying mammal is found in eastern Australia. While it is not exclusively a river mammal, it is primarily found in rivers and streams, where it feeds on invertebrates and aquatic insects.
Important Note: While some mammals like beavers and hippopotamuses are often associated with rivers, they are not considered true river mammals. They are semi-aquatic and spend a significant amount of time on land, relying on rivers for various activities like building dams (beavers) or cooling off (hippos).