Sea otters spend several hours a day grooming their fur to keep it clean and fluffed full of air. Without this constant attention, the fur becomes dirty and matted and loses its insulating properties. Sea otters also stay warm by generating a lot of body heat. They have rapid metabolisms and require lots of food calories to fuel them. In fact, most sea otters need to consume about a quarter of their body weight in food every day.
Sea otters conserve heat when resting by keeping their paws and hindflippers up out of the water.
These appendages have little or no fur and lose heat more rapidly than the rest of the body. Unlike land mammals, sea otters can dive under water for minutes at a time while hunting for food. Their large lungs allow them to take in lots of oxygen and transfer it to the blood efficiently, and their blood can absorb the excess carbon dioxide that accumulates during dives. Their eyes can focus under water and see well in dim conditions. And when otters can't find their prey by sight, their whiskers and paws help them find it by touch.