BRUNSWICK, Maine -- A marine biologist believes a humpback whale shielded her from a 15-foot tiger shark in the South Pacific.

Nan Hauser said she didn't understand the actions of the 25-ton whale that she met face-to-face in the Cook Islands. Then she saw the shark.

She's heard on a video telling the massive mammal, "I love you!"

The encounter took place in October, but Hauser didn't upload the video until Monday. It quickly spread via social media.

Hauser, president of the Center for Cetacean Research and Conservation, tells the Portland Press Herald that whales are "altruistic" and often hide seals from predators, but she has never experienced or read about anything about a whale protecting a human. "If someone told me the story, I wouldn't believe it," she said.

The Brunswick resident said she was oblivious to the shark during the tense, 10-minute encounter. The whale started to nudge her, and appeared to push her with its head. The animal also appeared to shield her with its pectoral fin.

Her research companions turned off an underwater video drone, fearing she was going to be mauled to death.

But Hauser kept her video rolling.

She suffered some bruises and scratches from the encounter, but was otherwise unscathed. She said that after she swam back to her boat, the whale surfaced nearby as if to check on her.

While Hauser credits the whale for protecting her, she acknowledges she can't know what the whale was thinking.

James Sulikowski, a marine biologist and professor at the University of New England who has studied tiger sharks, said he's not convinced that the whale saved her life. "The shark could have just been hanging around," he said. "There's really no way of knowing the whale's motivation."

Watch the video on YouTube.