<P> An adult's 32 teeth, particularly the molars, are flattened and rounded for crushing rather than cutting food . Seals and sea otters are the only carnivores with two pairs of lower incisor teeth rather than three; the adult dental formula is 3.1. 3.1 2.1. 3.2 </P> <P> The sea otter has a metabolic rate two or three times that of comparatively sized terrestrial mammals . It must eat an estimated 25 to 38% of its own body weight in food each day to burn the calories necessary to counteract the loss of heat due to the cold water environment . Its digestive efficiency is estimated at 80 to 85%, and food is digested and passed in as little as three hours . Most of its need for water is met through food, although, in contrast to most other marine mammals, it also drinks seawater . Its relatively large kidneys enable it to derive fresh water from sea water and excrete concentrated urine . </P> <P> The sea otter is diurnal . It has a period of foraging and eating in the morning, starting about an hour before sunrise, then rests or sleeps in mid-day . Foraging resumes for a few hours in the afternoon and subsides before sunset, and a third foraging period may occur around midnight . Females with pups appear to be more inclined to feed at night . Observations of the amount of time a sea otter must spend each day foraging range from 24 to 60%, apparently depending on the availability of food in the area . </P> <P> Sea otters spend much of their time grooming, which consists of cleaning the fur, untangling knots, removing loose fur, rubbing the fur to squeeze out water and introduce air, and blowing air into the fur . To casual observers, it appears as if the animals are scratching, but they are not known to have lice or other parasites in the fur . When eating, sea otters roll in the water frequently, apparently to wash food scraps from their fur . </P>

Where do sea otters live in the ocean