Sea Otters play a very vital role in their environment.  Sea Otters are referred to as keystone species, meaning that they play a very important role in their environment and without the sea otter the community would collapse.  Enhydra lutris has a very close relationship with kelp.  This is a mutualism relationship because both species benefit from the interaction.  The sea otters help the kelp by eating the sea urchins because if there is too big of a population of sea urchins the kelp is endangered.  The kelp in return provides and anchors for the sea otters while they are sleeping and doing daily activities.  (See also Habitat).  The kelp forest also provides shelter for many different animals that the sea otter often interacts with on a daily basis such as:  seals, fish, and shellfish.

     Sea Otters have very few predators, which are known.  Three of them are the bald eagle, white shark, and the killer whale.  The bald eagles tend to swoop down and catch sea otters when they are young.  The arctic foxes, red foxes, and wolverines have been thought to also be predators of the sea otter but that information is merely  based on one incident or remains found where these animals hang out.

     One important event that has showed the importance of the sea otter to its environment was in the 1900’s.  In the 1900’s the sea otters almost went extinct due to killer whales feeding on them.  The areas where the sea otters disappeared completely were taken over by sea urchins.  Due to this the areas where sea urchins were high the kelp began to disappear and became barren.  Due to this many animals’ habitats were ruined and many marine animals were affected by the sea otters population (Stephens, Tim).  Thankfully the sea otter was re-introduced and the sea urchin population was put back under control.

     There are numerous pathogens and parasites that impose otter populations, but most of them appear to be usually harmless.  One known is Acanthocephalan peritonitis which is one of the main causes of death in California sea otters.  This is caused by tiny worm-like parasites that enter the body with food, puncture the intestinal wall, and then later result in illness in the abdominal cavity.  Coccidioidomycosis is an infection that results from a soil-borne fungus.  The spread of this disease is not understood at this time and is still under research.  Microphallus pirum is a trematode which may cause enteritis because it is covered with sharp spines which may damage the gut lining.  Also Terranova decipiens is a nematode in which the larvae penetrate the wall of the intestine and may invade the organs.  In result the host may die or these parasites may lead to peritonitis.  For the most part sea otters are free of external parasites except for possibly a light infestation of mites (Halarachne miroungae) in the nasal cavity (Chanin, Paul).

      Sea Otters have not impacted humans significantly.  The one use that sea otters do have to humans is there fur.  There fur is used by humans for clothes and accessories.  Besides for retail there have not been any other reported uses of the sea otter by humans.