Pregnancy in the female sea-otter begins with a delay, the embryo first passes a latent phase lasting 2-3 months, during which it does not attach to the uterine wall (about 100 different species of mammals possess this feature; allows the mother’s body to choose the best metabolic period for pregnancy itself).
Immediately, the pregnancy lasts about 6 months (7-8 months in the northern sea otters).
Genera in females of most subspecies occur on coastal stones or on land. In 99% of cases one cub is born (“the bear”). In rare cases, twins are born, but under normal circumstances only one cub can survive.
Cubs are born a brownish-yellow color, weighing from 1.5 kg, covered with child’s down. Adoptions of alien cubs are common in sea otters, so the second cub of twins can survive if a female, whose baby is killed, adopts it.