First Surrogate Otter Mom Dies

03/06/2012 09:20 am ET | Updated May 06, 2012

Staff at California's Monterey Bay Aquarium are mourning the most remarkable sea otter they have ever encountered.

Toola, who died at age 15, was the first captive sea otter ever to serve as a surrogate mother to others, raising a total of 13 pups, some of which now lead their own packs in the wild.

She was rescued in 2001 and became mother to an orphaned pup weeks afterward.