The North American river otter, also known as the northern river otter and river otter, is a semiaquatic mammal that only lives on the North American continent, along its waterways and coasts.
 
Otters also have a pivotal role in river ecosystems. They are predators, meaning they help control the populations of food species they prey upon. This affects the ecosystem as a whole, and as a result, their presence is a signal that the ecosystem is healthy.