John Weisel envisioned his first ever trip to the wilderness of Isle Royale National Park—an island in the middle of Lake Superior—as a sort of sabbatical.

The trip was to be the last of a series of similar trips—Utah and New Zealand were among the earlier stops—during which Weisel sought to do things, and conduct research, that he’d never tried before.

“I had never taken a sabbatical until 2002, and then my wife had this great idea,” says Weisel, a professor of cell and developmental biology in the School of Medicine who studies the physical properties of blood clots. “She said, ‘Why don’t you go to a bunch of different places during the year? You can go for a month, then come back for a month, and do it again.’ I thought it was a great idea.”

For Weisel, an avid outdoorsman, a trip to the remote Isle Royale wilderness figured to be the perfect way to cap off his year of mini-sabbaticals: The island national park, which draws about as many visitors in a year as Yellowstone National Park draws in a day, is home to scores of wolves, an animal in which Weisel had long harbored an interest.

“So I just a wrote up a letter to one of the top wolf researchers in the U.S. (Rolf Peterson) and said, ‘Is there any way I can come up and work with you for a month?” remembers Weisel. “ But I didn’t get a response. Then I sent him an email, and he responded immediately. He said [my work] was so different he wasn’t sure how to respond. But he said, ‘Sure, come on up. I’m not sure what you can do, but we’ll work something out.’”

That something, it turned out, would lead Weisel to an unexpected, unplanned discovery—a research breakthrough about otters that was so coincidental that even Weisel seems somewhat surprised by it.

“The whole thing was serendipity,” he says.

Indeed, when Weisel first arrived at the park, he had no intention of turning up something new and exciting about otter hair. In fact, he really didn’t know what he was going to do at all.

“I figured I’d figure something out,” he says.

That he did. In the course of two trips, Weisel did a little bit of everything on the island. He studied the movements of the Isle Royale’s wolf population, waking every hour on the hour at night to track their movements by radio telemetry. He hiked the island’s many trails, getting to know a unique corner of America that few see. And he spent a good bit of time collecting animal droppings—maybe not the most glamorous task on the island, but one that ultimately led to his unexpected breakthrough.

“When I went back, I was collecting wolf scat,” Weisel explains. “They have a study where they are trying to identify each individual wolf on the island from the DNA in the scat. I did some hiking all over the island and collected all the scat [for the research] and at the same time, I took an extra tub and saved some for myself.”

In those containers were samples of all manner of animal hair—the animals being eaten by the Isle Royale wolves.

It was when he put the hair samples under a microscope, studying them via light and electron microscopy, that Weisel made his surprising discovery: The hair belonging to the otters, he quickly noticed, looked radically different than the hair of most any other animal on Isle Royale.

“In the process, I found out that otter hair had this unique structure,” Weisel says. “The hair had fins on it, almost like a Cadillac with fins sticking out the side. That was interesting in and of itself.”

Upon closer inspection, Weisel found that in otter hair the “fins” on one hair fit nicely and insert into the grooves in adjacent hairs. The pattern, repeated many times, creates a tight web-like structure to keep water away from an otter’s skin and prevents heat loss. The grooves between the fins also trap air bubbles, which add another layer of insulation.

The discovery helped explain why otters, unlike other marine mammals, have been able to survive even though they don’t have a thick layer of fat like dolphins or whales.

“It was interesting to learn something about how otters can spend a lot of time in the water and still maintain their body temperature,” Weisel said. “They don’t have much body fat, compared to dolphins. For me, it wasn’t a surprise, because I didn’t know enough to be surprised.”

But even though Weisel is no zoologist, the paper he wrote up about his discovery was picked up and published by the Canadian Journal of Zoology. The work has also attracted a good bit of media attention, and even popped up on the web site of a group advocating creationism. The group apparently thinks Weisel’s otter-hair finding is proof of a higher power, he said.

“It was immediately clear that something was very unusual here,” he says. “But I didn’t expect this paper to attract so much attention.”