One of the most popular attractions at the Monterey Bay Aquarium are the sea otters, and this weekend was especially popular with the arrival of a new–and unexpected–arrival.

Over the weekend, aquarium officials say they noticed a female otter lounging in the aquarium’s protected lagoon, which is visible from many of the facilities outdoor spaces. The otter appeared to be using the protected area to rest from the rough ocean water and winter storms in the area.

“It’s rare for a healthy sea otter to visit the pool so frequently—we started to wonder if she was doing all right,” aquarium staff wrote in their online blog. The next morning, around 8:30 a.m. (on Sunday), Aquarium staff witnessed a new pup resting on her belly, being furiously groomed by a proud momma.

Sea otters are marine mammals native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 31 and 99 pounds, making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter’s primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom.

Photo by Tyson V. Rininger, Monterey Bay Aquarium

Photo by Tyson V. Rininger, Monterey Bay Aquarium

The total population of sea otters were once estimated at 150,000–300,000 until they were hunted extensively for their fur between 1741 and 1911. As a result, the world population fell to 1,000–2,000 individuals living in a fraction of their historic range. A subsequent international ban on hunting, conservation efforts, and reintroduction programs into previously populated areas have contributed to numbers rebounding, and the species now occupies about two-thirds of its former range. The recovery of the sea otter is considered an important success in marine conservation.

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