The playful North American river otter is equally at home in the water and on land. It makes its home in a burrow near the water's edge, and can thrive in river, lake, swamp, or estuary ecosystems.

From the top of Shifting Sands dune in the Serengeti Plain of Africa a million mammals are in motion ... Both sweat glands and mammary glands produce water, salts, and proteins, all of which ...

For years, manatee populations have been negatively impacted by many factors. Here's what to know about the mammal's current ...

these mammals are divided into 13 existing species. Some can be found floating in freshwater rivers and lakes, while others swim across the Pacific Ocean, according to National Geographic.