Characteristics of Mammals That Live in Fresh Water

Mammals that live in fresh water come in many shapes and sizes, including a one-of-a-kind creature like the platypus, to rare freshwater dolphins and large rodents like the beaver and capybara. Despite being found around the world, some similarities are common to the animals that make fresh water their home.

  1. Swimming Abilities

    • The swimming abilities of freshwater mammals like dolphins and manatees are obvious, since they spend a majority of their lives in the water, coming up only to take oxygen. But rodents and furred mammals like otters also have great swimming abilities. An otter can reach speeds up to 7 mph while swimming underwater, and dive to depths of 60 feet. A hippopotomus can close its eyes and ears and remain underwater for up to six minutes.

    Large Tails

    • Many freshwater mammals have large tails to assist with swimming. A manatee has a large paddle-shaped tail to propel its large body while swimming. Flat, paddle-like tails are also apparent on beavers and platypus. A beaver also uses its large, flat tail to slap against the water and warn others of danger. A beaver uses its tail on land to balance while chewing down trees, while a platypus uses its tail to hold onto its young.

    Fur and Skin

    • Freshwater mammals have skin and fur that allows them to survive in the sometimes cold waters they live in. Beaver fur was once prized for thickness and waterproof characteristics. Beavers stay warm because a layer of warm air gets trapped under its top layer of fur. The pink Amazonian freshwater dolphin has the most unique skin. The rare dolphin's skin is pink, though scientists aren't sure why. One reason could be because of the capillaries that are close to the skin's surface.

    Diet

    • Some freshwater mammals are omnivorous, taking advantage of the many sources of food available to them in rivers, lakes and streams. Otters and freshwater dolphins exist on a diet of crustaceans, shellfish, small fish and aquatic insects. Manatees, hippos, beavers and other aquatic rodents are herbivores. Beavers get their nutrients from the tree bark they famously chew on, while manatees and hippos graze on aquatic plants like grass, leaves and algae.