Different otter species spend different amounts of time living with their mothers after birth. River otters stay with their mothers for about a year, usually long enough for her to become pregnant and deliver a new litter, while sea otter pups can remain dependent on their mothers for a period of five months to a year.
Sea otters typically only deliver one pup per litter, while river otters can give birth to as many as three pups at a time. Both types of otters typically learn to swim at around two months of age, and both river and sea otter pups are still nursing at this point.
After the river otter pup learns to swim, it will stop nursing at about 14 weeks old. At this point, the river otter pup will learn how to hunt along with its siblings and mother.
In addition to behavioral differences during infancy, river and sea otters have different habits during adulthood. While sea otters can sleep in water, river otters typically prefer to sleep on land. River otters can spend up to 48 percent of their day grooming their fur, while sea otters spend a lot of their time hunting and eating shellfish and other marine life.