It's not just adorable! Grooming is actually an incredibly important part of keeping this baby sea otter healthy. Joanne Manaster visited the Shedd Aquarium in Chicago and came back with a whole post for the PsiVid blog about the science of cute baby animals.
When an otter is raised by humans, there are many skills they need to learn, including how to feed themselves, groom themselves, and to sleep in the water. Unfortunately, once they are habituated to humans, they will not gain the skills needed to hunt, so cannot be released into the wild. On the other hand, the otter raised by the surrogate will gain all necessary skills and may be released to the wild in the future.
That's why Toola—the world's most influential otter—was so important. Those habits, including grooming, are a big deal in the wild.
From Shedd's website: "Keeping the pup's thick fur clean, dry and fluffed is essential to her survival. Sea otters are the only marine mammals that aren't wrapped in an insulating blanket of blubber. Instead, they have about 1 million hairs per square inch of skin, divided into an outer layer of thick guard hairs and an inner layer of dense, wooly underfur honeycombed with millions of tiny air pockets. The layers work together to keep water out and body heat in. If the fur becomes matted or fouled with pollutants such as oil, cold sea water penetrates to the otter's skin and the animal can quickly succumb to hypothermia. Otters shed their fur gradually and throughout the year so that they are never without this vital protection."