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A slime mould thinks like an animal — but has no brain

2021 08 07 hawke slimeBy David Hawke -- If things are appearing in your garden like they are appearing in our garden, then today’s topic of slime moulds should be of interest. Actually, slime moulds should be of interest to everyone, I would think, so here’s the info you need to know.

          The bright yellow blobs first came to life within our new raised beds, tucked in between the tomatoes and then along the heavy wooden frame. Is that a dead leaf? Was something spilled here? A closer look revealed… eww, looks like the cat barfed up something! How wrong I was.

          Turns out it was dog-vomit slime mould. Yeah, who names a thing that? But that’s what it was, so my apologies to cat lovers everywhere. And it’s not really dog vomit, it just looks that way.

          Although slime moulds are a strange and unusual life-form, they are fairly common and can be found with just a bit of searching. The challenge is, they appear and disappear overnight; so, keeping your eyes open along the trailside on your early morning walk will yield best results.

          For centuries, slime moulds were lumped in with fungi if speaking scientifically. But nowadays they have been re-assigned from the Fungi Kingdom over to their to very own Kingdom, the Protista. Talk about a coup.

          Even though a slime mould looks like a fungus, a closer look (a really, really closer look) will reveal that they have no chitin in their cell walls. Chitin is the tough covering of cells that helps give shape and form to a plant or mushroom. Slime moulds don’t have it and therefore are just a blob, laying there, supposedly without shape or form.

          But slime moulds know better, as they can indeed form shapes, and even travel! So, this brings us to that universal question, “Just what the heck is a slime mould?”

          Well, it’s not a plant nor a fungus (remember, no chitin), and it can move in search of food, even climbing up branches and tree trunks and, now get this, knows how to turn to avoid inhospitable areas. So, it can ‘think’ and ‘react’ like an animal while not having a brain. Cue the eerie music.

          Turns out that that blob of mould is actually millions of individual cells that can join together to create multicellular reproductive structures, or not, depending on their mood. When not looking for food (decaying wood fiber) they are looking for, you know, a partner. Air borne chemicals tell the slime moulds where to go and what to do when they get there and the colony is capable of moving en masse about one metre a night.

Slime moulds are much like a rock concert that humans attend: thousands of individuals reacting as one to the shared stimuli yet really all looking for the same thing… a partner. I’ll let your imagination take it from there. Think Woodstock, man.

          In recent years I have encountered five species of slime moulds, some with a cute informal name: dog-vomit, wolf-milk, raspberry foam, and one that looks like chocolate popsicles while another that forms an orange net-like structure that looks strangely like a model of the world wide web. All have been found on rotting hardwood logs. The dog-vomit slime that showed up in our garden was there because I used hardwood branches as filler under the expensive potting soil.

          While the individual slime mould cells are ‘always out there’ it seems that when food is scarce, they form these mega-colonies and share information as to who is smelling what and from which direction. That’s when we see these ‘structures’ perched on the logs.

          Heat, moisture and humidity all play a part in enticing slime moulds to rise up and be noticed. As soon as the sun hits them or a cool breeze blows by, the structure either ‘dissolves’ itself or the bulk of the individuals die and create a black crust.

          They are not harmful to humans nor our precious foods. In fact, they are needed to break down wood fiber into digestible bits that bacteria and true fungi can then take on. Within Nature there is a reason and purpose for everything.

          So, there you have it, slime moulds. Now you know. Try introducing the topic at your next dinner conversation to enlighten others!

Dave’s Notebook: Let me say how proud I am of our country's Olympians! Not so much for their medal winnings but for their pure sportsmanship at congratulating their opponents who came in both ahead and behind them.

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© 2021 David J. Hawke

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