a miniature cedar tree. Part of the appeal of Sugi moss in the garden is its tolerance of the conditions in Seattle, where the groundcover withstands the wear from raking and changes colors during the year from bright green to red and green when the red-stemmed capsules sprout.
We squatted down to take a closer look at the Sugi moss, and as Pete talked about encouraging this particular moss to grow, he rubbed his hand over the red capsules, sending a cloud of spores into the cold morning air. It was easy to see how the moss spreads on its own, with spores so small and light.
Still, some of the garden’s mosses were intentionally planted, and that winter break, the crew had been doing just that. They had shifted the main path slightly and added a rope barrier here and there, leaving behind bare patches of soil. They had collected moss from other parts of the garden, mostly areas out of view along the fence, and set the moss out in little clumps, right on the soil, like cookies set on a baking sheet. According to Pete, in only three years the moss will have spread enough to cover the bare soil and in only five years will look as if it has always been there.
Next we made our way up the stone stairway to the tea garden, a small fenced-off area open to the public only for weekly tea ceremonies. The tea garden was designed to feel as if it’s set deep in the woods, and as we walked up the boulder-lined steps, Pete explained that there are no cut stones in this part of the garden—they are all natural. Pointing out the moss growing in thick mounds between the stone steps and up along their edges, he commented that although this garden was built in 1960, the moss adds a patina that makes it appear much older. At the top of the stairs we headed to the left, where a series of stepping-stones set in a sea of moss leads to the teahouse. Slowly, I tiptoed from stone to stone, balancing carefully after each deliberate step so as not to tread on any moss. The uncomfortable placement of stones is intentional, serving to slow visitors down, encouraging mindfulness and focus as we pay more attention to our surroundings and the moment.
The moss sprouting up between the stones was a deliberate part of the garden, a desired urban patina. Some of it had been intentionally planted and gently managed, but moss is going to grow where it will. Maybe it’s time we embrace it.
A World in a Petri Dish
Water is life’s mater and matrix, mother and medium. There is no life without water.
—Albert Szent-Györgyi, Hungarian biochemist
When I finally found one, I couldn’t help shouting out in excitement. I’d been on a search all afternoon, on a microscopic safari over a petri dish. I’d plucked a world from outside and brought it inside to live on my desk, where I scrutinized it under my microscope. In what was just a small patch of moss lived an entire ecosystem.
It had started that morning when I’d gathered two small clumps of moss from under the maple tree in my front yard. I added some rainwater to a pair of petri dishes, set a clump of moss inside each, and left them to soak on the picnic table while I went about my morning routine. Later that afternoon, I’d retrieved the petri dishes, dumped the water, and then holding each clump of moss over an empty dish, squeezed it. The water poured out; like a wet sponge, the moss held a surprising amount of it. Carefully, I brought the dish back to my office, where the dissecting microscope lives, and spent the next few hours with my neck bent over the scope, searching for a certain tiny creature.
The remaining moss water was a minuscule floating jungle of debris, the brown fluff moving with animals invisible to the naked eye. I first found tiny, transparent, wormlike organisms that propelled themselves quickly, transforming into a compact ball and stretching back out again. I later learned they were rotifers. I also observed a couple of larger nematodes, translucent worms that look like they’re made of glass, their insides shifting about as they wiggled around. There were tiny dots, too small to see as anything but little blurs, swirling in circles, and teeny rice-like shapes sliding across the bottom, jerking away when they bumped into something. But it wasn’t until just before dinnertime when I finally found the object of my quest: a tardigrade.
These microscopic animals are famous for having survived in space; yet to me it seemed improbable that such accomplished animals lived in my yard in the city, even though I knew they could be found here. I desperately wanted to find one, while still half believing it was impossible. But only after I had stared at every movement in the dish, hoping for a tardigrade, there it was finally, almost larger than life, and exactly like I imagined. Once I saw it, I knew there was no mistaking it for anything else. The creature’s slow movement, eight stumpy legs tipped with long, curved claws framing a rotund body, plodding through the water, was very different from that of every other living creature in that dish. The tardigrade is also known as a moss piglet and water bear because of its obvious resemblance to those animals. Tardigrade means “slow walker,” but naming the animal for its plodding movements on the flat, slippery surface of a petri dish is unfair. Putting a tardigrade on such a surface is as unnatural as putting a sloth on the ground, or a human on ice. Placed in its natural home of mosses and lichens, a tardigrade uses its long claws to climb through the miniature plants with ease.
After my initial success, I continued looking for tardigrades around my yard. I collected moss from a dozen places, including on a maple tree, in the lawn, on the driveway, on rocks, the fence, and concrete stairs, and on the roof. To my surprise, the sample with the greatest abundance of tardigrades, the one in which they were a dime a dozen, was the moss from my roof. Not the moss in the grass, or the moss that clung to the tree bark, but the moss on top of our two-story house. I realized there must be thousands, maybe millions, of tardigrades on our roof crawling around in the Bryum argenteum moss above my head every day. Up there, where they are exposed to all the elements the Pacific Northwest can throw at them: hot sun in the summer, ice and occasional snow in the winter, and torrential rain in the autumn. But therein lies the key—rain.
I began keeping a large glass dish containing tardigrades and moss from our rooftop on my desk, where the creatures became my tiny pets. I added a little rainwater every couple of days to keep the dish from drying out in the warm house, and each morning I set it under my microscope and observed the tiny organisms living inside it.
But over one weekend the dish dried out, the loose debris turned into a hard crust, the moss became brown and crispy, and nothing moved. I added rainwater Monday morning and let it sit to see what would happen. A few hours later I poked around in the dish and found a tardigrade, compressed and unmoving. I prodded it with one of my dissecting tools and it moved a little, as though it were just waking up. Very slowly its legs rehydrated, like a balloon being blown up, until it was in a spread-eagle position. Eventually it started moving and righted itself, becoming more active.
Although tardigrades live on land and are often thought of as terrestrial, they are true water beings. Their lives are intrinsically tied to water. Many species live in marine environments and others can be found in freshwater environments, but many are limnoterrestrial, meaning they live in wet, soggy places, like lichens and mosses. The water bear requires a film of water around it for gas exchange, and without that water, it quickly desiccates and turns into a tiny, oval-shaped “tun,” which I observed when the dish dried out. Over the month I watched them, the dish dried out several times, and each time I added water, life soon returned.
It’s this survival ability that has made the tardigrade famous enough to be featured in popular culture, including the movie Ant-Man and the Wasp and the television show Star Trek: Discovery. Article after article rolls out regularly, declaring the tiny tardigrade the ultimate survivor, the animal that will outlast us all, the one that will survive the apocalypse. These claims may sound sensational, but there is more than a grain of truth behind the tardigrade’s survival story. It has survived five mass extinction events, after all; and it’s true that it is very adept at surviving harsh conditions by turning into a tun. But this fame comes from the study of only a handful
