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.

This South American otter is the world's largest, at some 6 feet long. It lives only in the rivers and creeks of the Amazon, Orinoco, and La Plata river systems. These huge members of the weasel ...