They seem to have an acute sense of smell and taste, but we don't really know how well they hear. They seem to be most sensitive to high-pitched sounds. An otter's fur keeps it alive in the icy water, so each otter spends up to four hours a day grooming to keep its coat in good shape. You'll often see otters rolling in the water and rubbing themselves-they're cleaning their fur and rubbing insulating air into the hairs. They're extremely limber, and their skeletons are very loosely jointed, so otters can groom every inch of their bodies-even the middle of their backs.
Females usually give birth to one pup a year, although twin births occur occasionally.
If twins are born, the mother abandons one because of the energy it requires to raise even one pup. The gestation period for otters is about six months. The female otter is able to delay implantation of the fertile egg for two to three months. Some scientists suggest that this may help ensure that the pups are born when food is plentiful. The exact mechanism that controls implantation is not known.