Between A Rock And A Hard Place, Life Thrives

7:14 minutes

Bacteria can thrive underneath rocks in extreme environments. Credit: Michael Wing

The Atacama Desert is one of the driest deserts on Earth. So dry, it makes Death Valley look positively lush by comparison. In the Atacama, you can look around and not see a living thing—no animals, no plants, nothing. Unless, that is, you know where to look. Hiding under translucent rocks, hardy bacteria eke out an existence where nothing else can. In this segment, science teacher Michael Wing and SciFri’s education program assistant Xochitl Garcia talk about these extremophiles, and an experiment that studies them on all seven continents.

[Explore the dry, dim world of hypolithic or “under rock” cyanobacteria and measure and compare colony growth in deserts around the world.]

Segment Guests

Michael Wing

Michael Wing is a science teacher at Sir Francis Drake High School in San Anselmo, California.

Xochitl Garcia

Xochitl Garcia was Science Friday’s K-12 education program manager. She is a former teacher who spends her time cooking, playing board games, and designing science investigations from odds and ends she’s stockpiled in the office (and in various drawers at home).

Segment Transcript

FLORA LICHTMAN: The Atacama Desert is one of the driest deserts on earth. It actually makes Death Valley look lush in comparison. In the Atacama, you can look around and not see any living thing– no animals, no plants, nothing– unless, that is, you know where to look. Joining me now to talk about that hiding place for life is my guest, Michael Wing. He’s a science teacher at Sir Francis Drake High School in San Anselmo, California. Welcome to Science Friday.

MICHAEL WING: Good morning, Flora

FLORA LICHTMAN: So tell me about this life form that lives in this very difficult-to-live place.

MICHAEL WING: Yeah, I will. Thanks for that introduction. I’m also the author of the book, Passion Projects for Smart People, published by Quill Driver Books. It’s coming out this summer.


MICHAEL WING: So hypoliths are rocks in the desert that have green stuff growing underneath them. The green stuff is cyanobacteria and algae. The rocks are usually quartz or marble, so they’re translucent. They transmit a little bit of sunlight through the rock to the underside, and it’s better for the cyanobacteria down there.

They get protection from ultraviolet light, and it’s a little more humid under the rock. So if you turn over a white rock in almost any desert in the world– including polar deserts like Antarctica and also mountaintops– you very often see a bright green film on the bottom side of the rock.

FLORA LICHTMAN: That’s the cyanobacteria?

MICHAEL WING: That’s the cyanobacteria. And usually there’s a little bit of green algae mixed in. So when conditions get too extreme for plants and animals, these are the last life left standing. And the name comes from the Greek. Hypo means under it. Lith means stone.

FLORA LICHTMAN: Hmm. And so that’s where you find them– under stones. And will any rock do? Or do you need a special kind of rock?

MICHAEL WING: You need a special kind of rock. You need a rock that will transmit sunlight to the underside. There’s one exception to that, but in general, the rocks are quartz or marble. The one exception is in some polar regions, especially Devon Island in the Canadian Arctic, frost heaving kind of lifts the rocks up out of their sockets, and light can get down underneath an opaque rock.

FLORA LICHTMAN: The cyanobacteria, I take it, need the light to live?

MICHAEL WING: Right, they’re photosynthetic. They need sunlight, but they can get by on as little as 1/10 of 1% of direct sun.

FLORA LICHTMAN: And they’ll get fried if they’re on the topside of the rock? Why not live there?

MICHAEL WING: That’s correct. I took some home from the Mojave Desert and put them on my classroom windowsill, and they just got bleached by the sun and died pretty quickly.

FLORA LICHTMAN: So you’ve been running an experiment to try to understand these hypoliths better. Tell us about it.

MICHAEL WING: Well, in 2010, my students and I started putting arrays of fake stones in deserts around the world. We use glass and marble squares from a tile supply store. And they’re the kind you might use to tile your bathroom or your kitchen. So we roughened them up with sandpaper to make their surface more natural, engrave our names and the year on them, and then we put them on the ground in sets of 60.

So we’ve been doing a couple of these a year, and now we have arrays of these– what we call artificial hypoliths– at 10 sites on all seven continents. So we have them on Devon Island in the Canadian Arctic, Svalbard, Antarctica, the Mojave Desert, California’s White Mountain Peak, the United Arab Emirates, the Atacama that you just mentioned in Chile, Australia, Namibia. And last summer I put some in the Himalayas, specifically on a high mountain pass in Ladakh in India. And the idea–

FLORA LICHTMAN: I want to hear more about that, but let me just do an ID. I’m Flora Lichtman, and this is Science Friday from PRI. It sounds like you’ve gotten to travel to a lot of cool places.

MICHAEL WING: I have. I love deserts. Deserts are beautiful no matter where you go– whether they’re polar deserts or hot deserts or mountaintops. And it’s been a fantastic excuse to travel, and I’m very lucky.

FLORA LICHTMAN: Science Friday actually got a chance to visit one of these experimental sites out in California’s Mojave Desert. Xochitl Garcia, Science Friday’s education program assistant was there– and is here with us now. Welcome Xochi.

XOCHITL GARCIA: Hi Flora. It’s nice to be here.



FLORA LICHTMAN: What was it like to visit one of these sites? Walk us through it.

XOCHITL GARCIA: So Michael gave us a set of GPS coordinates in the Mojave Desert. So we drove out, and it was three of us that went out there. Ariel Zych, who’s our education director, actually co-wrote this resource with Michael.

And so we went out to the desert, and we tramped out. We parked on a random side of the road, and we walked in towards this sort of– and bouldered up to this area that kind of looks Mars-esque. I don’t know if I’m exaggerating or not, but it looks like you’re on a Mars landscape. And you have to search for this small, square patch of white tile–

FLORA LICHTMAN: The bathroom tiles.

XOCHITL GARCIA: The bathroom tiles like Michael described– and then we actually got to dig a couple of those up and document the data from those. And so it was pretty amazing.

And then Michael advised us to go out randomly and drive to a different place and walk out, and just pick up white rocks. And it turns out when we picked up those white rocks, there were cyanobacteria on a lot of them, on the underneath. So you can find them naturally, and you can find them in these artificial hypoliths– these experimental setups that Michael and his team has put out.

FLORA LICHTMAN: Was it easy to find the tiles?



XOCHITL GARCIA: That is good. We actually had a couple minutes around there where we were searching, and we were like, oh my god, maybe mud washed through this basin and covered them up. So we had a little bit of time freaking out, but then we happened upon– we triangulated– there were three of us. And so we went in different directions and were able to find the sites.

FLORA LICHTMAN: It’s like a treasure map. It sounds like a real adventure.

XOCHITL GARCIA: It was. I really, really enjoyed it.

FLORA LICHTMAN: Michael, do you have other people checking on these? Who does most of the checking in on these sites?

MICHAEL WING: Yeah, that’s a good question– and not only the checking in but also the deployment. Most of these sites are near some scientific field station. I can check on the Mojave sites and the other California sites myself. But all these sites except one I have local contacts for.

FLORA LICHTMAN: Cool. So if people want to get involved, can they go to the Science Friday website– sounds like. ScienceFriday.com/rocklife? Do I have that right, Xochi?

XOCHITL GARCIA: Yes, that is where you can find the resource and also connect with Michael. So we have his website up there for this project. And on the Science Friday website, what we’ve done is on Science Friday Educate, we’re trying to connect learners with the data and the real field work.

And so we’ve put up some of Michael’s pictures as well as ours from three different sites– the Mojave, Devon Island, and the Namib Desert– and you can go through and look at these and grade them on a scale that Michael has created for the cyanobacteria growth. So it’s a pretty cool way to get into the data and the climate science.

FLORA LICHTMAN: Very cool. That’s all we have time for. I’d like to thank Michael Wing. He’s a science teacher at Sir Francis Drake High School in San Anselmo, California. And Xochitl Garcia– she’s the Science Friday education program assistant. Thank you both.

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