Size

• According to the "National Audubon Society Field Guide to Mammals," the male sea otter can reach lengths of 71 inches, with the females usually smaller. The tail of this weasel can be 14 inches long, and the creature can stand almost 9 inches high at the shoulder. The sea otter male averages around 65 lbs., with the females about 45 lbs.; those that live in the more northern waters are usually larger than those found farther south.
  
  

Geography

• The sea otter once lived in the shallow waters within a mile of the coast from as far south as Hokkaido Island in Japan up the coast of Siberia through the Aleutian Islands off Alaska. The sea otter lived southward from Alaska all the way along the Pacific Coast of North America to Baja, Mexico. As of 2010, the sea otter no longer exists in any significant numbers near Japan, but still occupies the coasts of Russia, British Columbia, Alaska, Washington, Oregon and California.
  
  

Diet

• Only man and some primates, among all the mammals of the world, make use of tools better than the sea otter. The sea otter dives down as deep as 330 feet, holding its breath for up to five minutes in search of a meal and returning with both a shellfish and a rock. The otter uses the rock as a hammer or a tool to crack open the shell. Sea otters eat as much as a quarter of their own body weight in food per day, says the Defenders of Wildlife website, with such things as sea urchins, snails, clams, crabs and abalone in their diet. The mammal's fondness of abalones makes it an enemy of fishermen who depend on abalone harvesting to make a living.
  
  

Effects

• The sea otter lacks any fat to insulate it from the cold waters in which it resides, so the animal depends on its fur--the thickest fur of any creature--to provide warmth. The fur of the sea otter consists of as many as one million individual hairs per square inch. This makes for a valuable pelt and was almost the undoing of the species, as fur traders hunted the creature nearly to extinction. By 1911, biologists believed the sea otter was extinct, but a group of about 300 showed up off the California coast. Today the southern otters have protection from the Endangered Species Act, with its main threat coming from oil spills that can rob its fur of its ability to keep the animal warm, ending in death for the otter.
  
  

Population

• Before hunting brought the animal's population to near extinction, there may have been as many as one million sea otters in the world. The numbers as of 2010 include about 2,800 otters off of California, with from 64,600 to about 77,300 otters off the coastline from Washington through Alaska. Russia's sea otters number around 15,000, with as few as a mere dozen off the coast of Japan.