Sea Otter

• The head and body of the sea otter ranges from about 22 to 51 inches, and the tail is from nearly five to 13 inches, making its entire length 27 to 64 inches. The National Geographical Society indicates that they are typically 4 feet long and weigh 65 lbs. Male otters can weigh as much as 99 pounds, according to Otternet. Sea otters are usually larger in northern areas.
  
  

River Otter

• The river otter, also referred to as the giant otter, weighs between 60 and 70 lbs, with the males being slightly larger. From head to tail they are usually about 6 feet long, according to the Philadelphia Zoo.
  
  

Characteristics

• Both sea and river otters are mammals that live on a diet of fish. Sea otters have short claws that are semiretractable, while river otters have nonretractable claws. Both have ears that close when they dive underwater.