Short Wave - Meet The 'Glacier Mice.' Scientists Can't Figure Out Why They Move.

Episode Date: June 3, 2020

In 2006, while hiking around the Root Glacier in Alaska, glaciologist Tim Bartholomaus encountered something strange and unexpected on the ice — dozens of fuzzy, green balls of moss. It turns out, other glaciologists had come across before and lovingly named them "glacier mice." See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, everybody. Emily Kwong here, and I'm joined today by NPR science correspondent Nell Greenfield Boyce. Hey, Nell. Hello, Emily. So listen, I've got a quirky little mystery for you. Oh, go on. I love a mystery. So back in 2006, there's this researcher, Tim Bartholomis, and he was hiking around the root glacier in Alaska. Tim's a glaciologist at the University of Idaho, and he was there just going about his work, setting up scientific instruments, you know, pretty typical stuff, when suddenly he was

startled by something strange on the ice. What the heck is this? You know, I wasn't anticipating that. What did he see? Well, scattered across the vast whiteness of the glacier were these bright green balls, like dozens of them. Kind of round, they're sort of like the size of small decorative couch cushions, and they're just resting there on ice and they're bright green in a world of white. He was looking at balls of moss. Moss balls? Moss balls. But not like the moss you might see in the woods. These balls are not attached to anything. It's just balls of moss that are found sitting on the glacier ice,

kind of like green tribbles. Do you remember that famous Star Trek episode when all these furball looking things were taking over the enterprise? Oh yeah, the trouble with tribles. Oh, yeah, the trouble with Tribbles, original Star Trek. They seem to be gorged. Gourged? On my grain? Kirk, I am going to hold you responsible. The tribbles were so cute. So these moss balls, they look kind of similar?

Yeah, they're just green. Yeah, soft and squishy and kind of like a sponge. A really soft, lush, green moss. So today on the show, we give you a moss ball mystery, why glaciologists are scratching their heads over how these moss balls move and most intriguing how they seem to move together. It's going to be fascinating. Stick around. I'm Emily Kwong, and this is Shortwave, the Daily Science podcast from NPR. Okay, so Nell, you told us that Tim Bartholomis was surprised that he came across the glacial moss balls,

but other researchers had encountered them before, right? Yes, they're rare. I mean, they don't grow on just any glacier. It seems like conditions have to be just right. But researchers have spotted them for decades and they've seen them in several places, like in Alaska, Iceland, Svalbard, South America. Wow. And, you know, people who see them are generally pretty fond of them. I mean, in the 1950s, an Icelandic researcher described them in the journal of glaciology, and he called them Yoclamis or glacier mice. I love that.

Glacier mice. Okay. So what do we know about these little fuzzballs? As you can imagine, there's limited research. But we do know they can be composed of different moss species. So researchers think they form around, you know, like a little bit of rock or a clump of dust. And they just grow up to be pretty big, like six inches across or something. Whoa.

And here's the cool thing. These moss balls move around. And it turns out they move in a coordinated way, almost like a herd. Okay. That's amazing. Let's take the first part. Because when I think of moss, I don't think of movement. You know, it's pretty static.

I know. But researchers have speculated in the past that, they must be moving because otherwise the bottom of the moss ball would be dead. It wouldn't have living moss. But if you pick one up off the glacier and you turn it over and look, you can see there's actually green living moss all around the ball. So they've got to be sort of moving around rolling in some way. Okay. Because otherwise, if they weren't, that bottom would die against the cold ice on the glacier. That's right. And so scientists have actually dissected some moss balls and they put accelerometers inside them. An accelerometer, that's the device that measures movement. Right, right. So they cut into the

moss balls and they stuck this device in them and found that the balls were rotating. And, you know, here's what the researchers thought was going on. So these balls can sometimes be found kind of teetering on a pedestal of ice. And the idea is this pedestal might form because the moss ball kind of insulates the ice that is right underneath it, preventing that ice from melting as fast as the surrounding ice. And And so what scientists suspected is that you'd get this ball kind of like teetering on the top of a pedestal and then eventually it would tip off and just roll away. Gotcha. Okay. But the movement isn't random at all, right? You said earlier that it appears moss balls are moving in a coordinated way. So how exactly does that happen? That's what brings us back to Tim Bartholamus. So, you know, he's the University of Idaho glaciologist who was startled by these moss balls in Alaska. And he's actually married to a wildlife biologist.

Her name is Sophie Gilbert, and she's also at the University of Idaho. And she basically had a very similar experience of running into the glacier mice and being totally taken with them. They're so weird and interesting looking. They really do look like little mammals, little mice or chipmunks or rats or something running around on the glacier, although they run in, you know, obviously very slow motion. So in 2009, these two scientists went to that glacier, root glacier in Alaska, and they were there for a teaching gig. But in their free time, they decided to track the movement of moss balls. Here's what Sophie said.

Most people who would look at them would immediately wonder, well, I wonder if they roll around out here in some way. You know, tumbleweeds come to mind, which are obviously totally different, but also round and roll around. Okay, so they decided to track the moss balls, I guess, to see where they're going and how they're moving. how did they do that? Sophie is a wildlife biologist, right? So she had this idea to tag them, sort of like ornithologists, tag birds or something.

And she came up with this way of winding a metal wire through the moss, kind of like a bracelet. Brilliant. Or a sort of loop with an identifying sequence of little colored beads on the wire. And so the researchers could identify

each individual moss ball and then track their precise location for a couple of months. Going into this, Tim told me he thought the balls would just kind of be randomly rolling around. But what we actually found is that the whole colony of moss balls, this whole grouping, moves at about the same speeds and in the same directions.

And those speeds and directions can change over the course of weeks. That is so wild. Right. It's crazy. Yeah. And so, you know, they had all these research results. It was something that was kind of a side project. They hadn't really written it up or anything. And then they were at this happy hour with a Washington State University colleague named Scott Hodling.

And they started talking to him about this. And he was like, wait, wait, what? So he decided that he wanted to collaborate with them and really lit a fire under them to get all this data analyzed and written up. And the three of them have published their findings in the journal Polar Biology. And what did they find? According to their research, the balls move an average of an inch a day. and, you know, it's this kind of choreographed formation. Wow.

Tim said it was like a flock of birds or a herd of wildebeest. When we visited them all, they were all sort of moving relatively slowly and initially towards the south. Then they all started to speed up and kind of start to deviate towards the west. And then they slowed down again and progressed even further to the west. So do we know why these mossball colonies are moving in this way? They considered several possible explanations. The first and most obvious one is that the balls were just kind of rolling downhill. But measurements showed that no, the moss balls were not just going down a slope.

Okay, but what about the wind? Because wind changes direction. Like, could the wind blow and push them like tumbleweeds? They thought of that, too. They checked the dominant direction of the wind, but they told me, you know, the wind doesn't explain it either. And so then they said, well, maybe it's the direction of the incoming solar radiation and how, you know, that melts the ice or something. And they looked at that, but they didn't find any associations there either.

So, you know, they looked at slope, wind, sun. And none of them explained the directions that the moss balls were moving. And so we still don't know. I'm still kind of baffled. So this is the mystery you promised. The scientists just don't know why they're moving. Yeah, yeah. And it's fun and also, you know, intriguing.

Other scientists are thinking about this. I talked with this one researcher, Ruth Matrim, with the Danish Meteorological Institute. And she's long admired glacier mice after seeing them in Iceland when doing some field research there. She said to me that, you know, probably the explanation is somewhere in the physics, like the heat and the energy at the surface of the glacier and the melting and all of that stuff can get pretty complicated. But, you know, right now, like, they just don't know. What would it take to know for scientists to figure this out? More research, you know. And obviously it's not like this is a top research priority or something.

But the study of life on glaciers has really taken off in the last few years. People used to think glaciers were this kind of sterile, lifeless, cold place. But we now know that it's full of bacteria and algae and, you know, mysterious life forms like these moss balls. Hmm. And does anything live inside the moss ball? Yeah. There was a study back in 2012 that found there's little critters in there. There's like simple worms and even water bears. Oh, really? Okay. I love water. If you're listening to, this and you don't know what water bears are. I highly suggest you Google image them. They're so

interesting. Nell, I'm delighted to know about this abundance of life on glaciers, moss balls rolling around, doing their thing. I'm wondering, too, are they endangered in any way by ice melt on the glacier? I guess they could be, depending on the glacier. They're not found just everywhere. It seems like conditions have to be perfect. And, you know, exactly why they form in some places and not other places is something that the researchers are interested in. Tim Bartholomis told me he went back to Root Glacier recently for other reasons and did this sort of cursory check to see if any of the moss balls they tagged more than a decade ago were still there and he didn't see any. But he did see plenty of others. He said, you know, presumably they're

just out there on the glacier doing their moss ball thing. He wants to go back again to look in earnest for the ones that he and Sophie tagged. And maybe they could even get like a time-lapse video of these things moving. I mean, would Wouldn't that be cool to see this like herd of green, fuzzy, mice-like things, kind of creeping across the ice? I would. I would love to see that video. Now, thank you for bringing us this much-needed dose of delight, this moss ball mystery. You're welcome, Emily. This episode was produced by Abby Wendell, edited by Viet Le, fact-checked by me, Emily Kwong,

back tomorrow with more shortwave, the Daily Science podcast from NPR.