Geography

• The river otter's habitat in North America ranges throughout much of Alaska, with the exception of the far northern sections, across most of Canada, the Pacific Northwest, the Deep South, the Great Lakes, through New England and along the mid-Atlantic coastal plain.
  
  The sea otter's North American habitat is along the coastal waters of the Pacific Ocean, from southern California, northward to Alaska.
  
  

Freshwater Versus Saltwater

• While the river otter’s habitat is fresh water, the sea otter is a marine mammal. River otters will reside in rivers, lakes and ponds in woodlands, with this type of otter capable of long extended journeys onto land. However, the sea otter rarely leaves the water, floating offshore where it takes advantage of foods, such as abalone and mussels, according to the "National Audubon Society Field Guide to Mammals." Sea otters like to be where extensive beds of a seaweed-like plant, called kelp, exist. They also will look for shallows with rocky bottoms.
  
  

River Otter Dens

• The river otter lives in a den that it usually digs into a river bank. In the summertime, the den has an entrance above water, while in the winter, the entrance is below the surface of the water. The den typically includes a main nest area, which may have some sparse grasses, sticks, reeds or other vegetation lining it. River otters will often live in close association with beavers, using the ponds that beavers create with its dams as its home and using abandoned beaver lodges as its own.
  
  

Sea Otters and Kelp

• The sea otter’s association with kelp beds within its habitat stems mostly from its need for cover from predators. The sea otter will watch for threats, such as killer whales and sharks. If it spots one of these predators, it will go into the thick kelp to escape detection. The sea otter will also drape a long piece of kelp over its body when floating on its back and eating. The kelp acts as a tether, keeping the sea otter in the same spot as it enjoys its meal.
  
  

Size

• Depending on how old a river otter is, its sex and the amount of food that it can find, this type of otter may range over a 50-mile area along a river or stream during the course of a year. On the other hand, the sea otter stays within a more established area, with very few being more than six-tenths of a mile to one mile off the shoreline.