Bridge to Nature: Glaciers, Slime Molds, and Slugs

After two weeks of posting sentimental, smoke-from-the-ears thought-provoking stuff, I thought it was time to throw off the maudlin. Let’s talk about slugs and slime molds.

Quick! What do glaciers, slime molds, and slugs have in common? Quite a lot. In fact, this could be a great parlor game.

Hubbard Glacier, Alaska

The most obvious common bond is that they’re all slow. And yet, they don’t stop moving. Unrelenting, you might say.  They’re also a way of Mother Nature making us feel humble. Think you’re all that? Virginia Woolf once said the rock you kick will outlast Shakespeare. Glaciers, slime molds, and slugs will all outlast Shakespeare.

Another common bond is that you can find them all in Alaska, which is where we were touring last week. Alaska is a unique place with large areas of wilderness yet to be discovered as you venture through forests and ocean inlets.  It also, therefore, contains many things whose way of existence seems completely alien. You can’t help thinking, how does evolution favor THAT? But the more you learn, the more you realize nature has many ways of propagating itself that we can only guess at.

The Clever Slug

courtesy Trees for Life

Clever might not have been the first adjective that came to mind about slugs. In fact, your first thought might have been Ick! (Unless you are Professor Barbara in Montana, whose eloquent defense of mud I shared back in April — she knows of the cleverness and nobility of slugs). Slugs are a critical part of the ecosystem.

  • Slugs eat decaying matter, and will help clear a garden of rotting leaves, dead twigs, and even dung
  • Slugs are a good protein source for other predators that eat insect pests, attracting toads and birds

We were on a hike through the vast Tongass National Forest in Alaska last week and our guide, Laura, did warn us about slugs. The temperate (i.e. cold) rainforest was a habitat perfect for these fat black ones spread all across the hiking trail, as well as much longer green, green and brown, and even camouflage-colored slugs. The black ones, according to, were invaders from Europe.   As invaders often do, they had a secret weapon. Apparently,  if you step on them, the tarry substance that sticks to your shoe is quite difficult to remove without a blow torch or an ice pick.

Well played, European Black Slug! What a wonderful defense mechanism because we didn’t step on a single one. All along the column of hikers, you’d hear the person in front call out, “Slug!” Then, the refrain would echo down the line as each of us passed: “Slug…Slug…slug…Omigod SLUG!…ugh Slug…” I couldn’t help but think of the Monty Python sketch where they all start singing, “spam, spam, spam, spam, spamety spam!!! spametty-spam-spam-spam-spam….”

The slug’s other clever defense is, theoretically, a bad taste. Not as in enjoyed the movie version of “Fifty Shades of Gray” but as in tasted like rotting matter. I say theoretically because there’s no way to know if that’s exactly why the ravens spit them out. There might be a French delicacy of slugs au poivre somewhere, but not in Alaska. According to Laura, whenever birds or animals bite down, they just get a mouthful of the slime. Sticky tar slime.

OK, even I admit it. They are kind of icky. I couldn’t even bear to post one of the pictures of a man handling a Giant Black Slug, a picture taken in… you can guess where… Australia, of course! All giant mutant creatures seem to live in Australia.

However, slugs do have — how to put it? Interesting sex lives. They are hermaphroditic — meaning both male and female. Slug sex involves hanging from a branch where both of them extrude these giant blue…well, let’s just say you can watch the Youtube video to blush in private.

The Sublime Slime Mold

Guide Laura was a bit older, with frizzy grey hair and a throaty, used-to-be-a-smoker voice. But she was able to go from alto to soprano because she squealed at one point, “A slime mold! Look — it’s a slime mold, the first of the season!”

photo by Katie Krolic

She went on to make a convincing case for how stupendous these molds are. And she was not the only person excited about slime molds.

Frederick Spiegel, a biology professor at the University of Arkansas and an expert on slime molds, first encountered them nearly 40 years ago. “I thought they were the most beautiful, sublime things I’d ever seen,” he said. “I said, ‘I’ve got to work with these.’”–, “The Sublime Slime Mold.”

First of all, a slime mold is neither plant nor animal. It’s also not a fungus, although it looks like one, and many molds are fungi. What exactly constitutes a fungus? Well, may you ask. I can Wikipedia with the best of them, which is good, since all I remember about High School Biology was  …. that the teacher had big square black glasses and was nice…so actually I don’t remember anything about High School Biology. But I can look it up, and it turns out a fungus is a multicellular spore-producing organism that feeds on dead plant or animal material. A slime mold is technically a type of amoeba, a single celled organism which can act as multicellular and colonize.

You read that right. Slime molds colonize; the little amoeba single-celled bits coagulate with their fellow amoebas in order to move, eat, and come for your chocolate. Oh, yeah, that’s right. Scared now?  Slime molds are said to be one of the models for the creature in The Blob. According to Dr. Spiegel there, slime molds looking for food will gather together in tandem like a “moving sausage.”

According to Laura the guide, the slime molds will appear out of nowhere, change colors as they grow, and ultimately throw off spores so that they can move from log to dog to frog to bog (couldn’t resist) until you have this giant mass that looks like dog vomit or a pretty flower, depending on your point of view, spreading on your fauna. When the weather changes again, they dry up and disappear.

Think this is all hoo ha? There’s a video in this article at showing a slime mold solving a maze.  As the helpful researchers quoted by PBS discovered, you could put a trail of Cheerios down and track a slime mold moving all across Canada. Perhaps here I might speculate about putting a trail of Cheerios that leads up through the White House, but I’ll just leave that to your imagination.

The Inexorable Glacier

Obviously, among my trilogy for this post, glaciers are the pretty ones on the list. I know you’ve been waiting for me to get to the glaciers, since they’re the fashion models for Mama Nature. That’s not the only thing that makes them not like the others on my list.

Glaciers are technically not living organisms, whereas slime molds and slugs definitely are. Living organisms have to exhibit a handful of key life processes, particularly breathing, eating, and reproducing. Glaciers don’t breathe. Although, when you hear a glacier calving — breaking off ice sheets that turn into icebergs — it sounds a little like breathing. If thunder can be called breathing.

A glacier is a persistent body of dense ice that is constantly moving under its own weight; it forms where the accumulation of snow exceeds its ablation (melting and sublimation) over many years, often centuries.

Glaciers are a glimpse into the past because they’re ancient, by definition. Glaciers are accumulations of ice and snow that take centuries and millennia to develop. They’re moving ice sheets — where snow has fallen and not melted to a sufficient degree that the ice crushes all the air out of itself, turns blue (no air), and pushes downhill, ripping through rock while it goes. If a rock outlasts Shakespeare, glaciers outlast the rocks.

There are mountain glaciers and ocean glaciers (cirque glaciers and tidewater glaciers). They carve valleys through rock — as noted in one entry — the mountains in The Return of the King , where they were lighting the beacons were carved out by glaciers. There are moraines, cirques, aretes, ogives,  and pyramidal peaks — the French were fond of labelling glacier phenomena apparently. And glaciers contain 90% of the freshwater in the world.

Glaciers worldwide are getting smaller; 90% of them receding according to one estimate. Since glaciers are buildup of ice, most of them formed during the Ice Age around 12,000 years ago. If you read up about Ice Ages, you can learn that the earth has gone through cycles of ice, where mountains and glaciers advance and retreat repeatedly over the giga-years. We are at the end of one of those ice ages, so it would be natural anyway for ice to either be advancing or retreating.

What’s unique about our age — certainly sad, if  you appreciate the beauty of glaciers — is that the ice is retreating so quickly that we can see it changing year over year. That’s “unnatural” on the earth’s time scale. The park rangers can see it in Alaska, photographs document it, and even visitors who return year over year will notice that the glaciers are getting smaller every year.

At the same time, if the glaciers are retreating slightly — for now — that means the ocean is expanding. The ocean is full of all sorts of evolved life that make slime molds and slugs seem pretty ordinary.

Mendenhall Glacier, Juneau

Ultimately, glaciers, like slime molds and slugs, are all beautifully persistent bodies. Persistent implies continuing “against all odds.” Climate change will impact all of these, but like many natural phenomena, they evolve and adapt. Glaciers may recede now, but they have come and gone in cycles of millions of years. They’ll be back. Maybe glaciers will even learn how to solve mazes.

Brought to you by today’s Daily Post: bridge

0 Replies to “Bridge to Nature: Glaciers, Slime Molds, and Slugs”

  1. Well that was interesting..,, Who new that those slimy little buggers could be so erotic…. Could call that a blue goo movie…. Then down the rabbit hole I went to San Pedro and that BIG BLACK SEA SLUG…, Blue goo Slimy mold Mud That’s what I’m talking about!!
    Think before you speak. Read before you think – FRANNY LEBOWITZ

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