Sea otters feed primarily on a variety of large invertebrates, including sea urchins, abalone, rock crabs, kelp crabs, and clams. Their ability to use tools to break open their food makes sea otters unique among marine mammals. Southern sea otters occupy hard and soft sediment habitats from the littoral zone to depths of about 164 to 328 feet in protected bays to exposed outer coasts. Most individuals occur between shore and the 65-foot depth contour. Southern sea otters prefer unpolluted waters which are free from human disturbances and which contain sufficiently abundant prey to fulfill their energy and nutritional requirements.
Sea otters depend on their clean , water-resistant fur for insulation against the cold.
Their pelts contain about one million hairs per square inch, the densest fur of any animal. Declines in the southern sea otter population in the 1970s have been attributed primarily to entanglement in fishing gear. Current threats to the southern sea otter include habitat degradation from oil spills and other environmental contaminants, prey depletion by human exploitation, shooting, and entanglement in fishing gear. Other threats to sea otter survival includes disease, contamination of the ocean environment, and accidental drowning in equipment used by fishers.