Otters are known for splashing around. But Toola, a renowned sea otter at the Monterey Bay Aquarium in California, made a bigger splash than most.

Toola died Saturday from "natural causes and infirmities of age," according to the aquarium, ending an 11-year career in which she raised 13 orphaned otter pups and inspired a law to help her wild relatives. Toola was "arguably the most important animal" in the 28-year history of the aquarium's Sea Otter Research and Conservation program, according to an obituary on its Tumblr page. She was 15 or 16 years old.

"I will argue that there is no other single sea otter that had a greater impact upon the sea otter species, the sea otter programs worldwide, and upon the interface between the sea otters' scientific community and the public," aquarium veterinarian Mike Murray says in a statement.

Toola first came to the Monterey Bay Aquarium in 2001, after she had been found stranded and pregnant about 150 miles north at Pismo Beach. She was suffering from toxoplasmosis, a parasitic brain infection spread by cat feces. While the disease is common and relatively mild in humans who own pet cats, it poses a major threat to wild sea otters. (Scientists believe otters may be exposed by improperly discarded cat litter that winds up in freshwater runoff and, ultimately, the ocean.)

The Toxoplasma gondii parasite had already infected Toola's brain when she was brought to Monterey Bay, causing frequent seizures and offering little hope she would survive. Aquarium vets put her on a twice-daily anticonvulsant medication, which helped control her seizures but also meant she'd likely never return to the wild. A few weeks into her stay, she gave birth to a stillborn pup.

But just when things seemed darkest for Toola, she emerged as a leading light for her troubled species. An orphaned sea otter pup had arrived at the aquarium around the time Toola lost hers, prompting officials to put the two together and "see what happens," spokeswoman Alison Barratt tells the San Francisco Chronicle. Toola soon became the first otter ever to serve as a surrogate mother for a stranded pup, teaching it valuable sea-otter skills like dissecting crabs and opening clamshells with rocks.

This training and nurturing went beyond what humans could have provided, allowing the pup to be released back to the wild once he grew up. As the Chronicle reports, that pup is "now king of a pack at Elkhorn Slough, and has fathered countless pups himself." And Toola was far from finished — she went on to raise 12 more pups over the following decade. Of her 13 total adoptees, 11 have been released to the wild so far (five are still monitored, and six have either died or lost their tracking tags). Two still live at the aquarium, too young to go out on their own.

On top of Toola's direct service to her species, she also inspired a California law aimed at saving wild sea otters. Moved by Toola's story, then-Assemblyman Dave Jones introduced a bill to boost protections for California sea otters. The bill, which became law in 2006, did three main things: It required toxoplasmosis warnings on cat-litter bags, created a check box on tax forms letting people donate to the California Sea Otter Fund, and increased state funding for sea-otter research and conservation. The CSOF has already raised more than $1 million in voluntary taxpayer donations to help sea otters, according to the Monterey Bay Aquarium.

Since Toola's arrival, the aquarium has also assigned other sea otters to foster orphaned pups, something no one knew was possible before she did it. And this legacy remains important for her species, which is struggling in many places despite decades of rescue efforts. Decimated by fur trading in the 19th century, sea otters rebounded after a 1911 hunting ban, but their comeback has been incomplete, with only about 2,700 now in California — down from an estimated peak of 16,000. A record-high 335 California sea otters were found dead, sick or injured in 2011, about 15 percent of which likely died due to shark bites, the U.S. Geological Survey reported last month. The other reasons for this decline aren't entirely clear, but many scientists point to coastal pollution, including terrestrial animal diseases like toxoplasmosis.

Having persevered — and even pioneered — in the face of such threats, Toola will go down as a hero in sea-otter history, says Andrew Johnson, manager of the Monterey Bay Aquarium's Sea Otter Research and Conservation program.

"Toola was without question the most important animal in the history of our program," Johnson says in a statement. "She showed us that captive otters could successfully raise orphaned pups for return to the wild. She inspired a critical piece of legislation that is helping protect sea otters. And she inspired millions of visitors to care more about sea otters. We will miss her."

For more about sea otters and toxoplasmosis, see the video below:

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