<P> Births occur year - round, with peaks between May and June in northern populations and between January and March in southern populations . Gestation appears to vary from four to twelve months, as the species is capable of delayed implantation followed by four months of pregnancy . In California, sea otters usually breed every year, about twice as often as those in Alaska . </P> <P> Birth usually takes place in the water and typically produces a single pup weighing 1.4 to 2.3 kg (3 to 5 lb). Twins occur in 2% of births; however, usually only one pup survives . At birth, the eyes are open, ten teeth are visible, and the pup has a thick coat of baby fur . Mothers have been observed to lick and fluff a newborn for hours; after grooming, the pup's fur retains so much air, the pup floats like a cork and cannot dive . The fluffy baby fur is replaced by adult fur after about 13 weeks . </P> <P> Nursing lasts six to eight months in Californian populations and four to twelve months in Alaska, with the mother beginning to offer bits of prey at one to two months . The milk from a sea otter's two abdominal nipples is rich in fat and more similar to the milk of other marine mammals than to that of other mustelids . A pup, with guidance from its mother, practices swimming and diving for several weeks before it is able to reach the sea floor . Initially, the objects it retrieves are of little food value, such as brightly colored starfish and pebbles . Juveniles are typically independent at six to eight months, but a mother may be forced to abandon a pup if she cannot find enough food for it; at the other extreme, a pup may nurse until it is almost adult size . Pup mortality is high, particularly during an individual's first winter--by one estimate, only 25% of pups survive their first year . Pups born to experienced mothers have the highest survival rates . </P> <P> Females perform all tasks of feeding and raising offspring, and have occasionally been observed caring for orphaned pups . Much has been written about the level of devotion of sea otter mothers for their pups--a mother gives her infant almost constant attention, cradling it on her chest away from the cold water and attentively grooming its fur . When foraging, she leaves her pup floating on the water, sometimes wrapped in kelp to keep it from floating away; if the pup is not sleeping, it cries loudly until she returns . Mothers have been known to carry their pups for days after the pups' deaths . </P>

What is the difference between sea otters and seals