Slime Mold: Intelligence

Ten Things I Like About... Podcast

Summary: Can an organism without a brain be smart? You bet! Join Kiersten as she discusses some of the smart things slime mold can do.

For my hearing impaired listeners, a complete transcript of this podcast follows the show notes on Podbean

Show Notes:

“Slime Molds” by Dr. Sharon M. Douglas, Department of Plant Pathology and Ecology, The Connecticut Agricultural Experiment Station. https://portal.ct.gov

“Eight smart things slime molds can do without a brain,” by Alissa Greenberg. Nova, September 21, 2020. Https:://www.pbs.org

Music written and performed by Katherine Camp

Transcript

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Kiersten - This is Ten Things I Like About…a ten minute, ten episode podcast about unknown or misunderstood wildlife.

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Welcome to Ten Things I Like About… I’m Kiersten, your host, and this is a podcast about misunderstood or unknown creatures in nature. Some we’ll find right out side our doors and some are continents away but all are fascinating.

This podcast will focus ten, ten minute episodes on different animals and their amazing characteristics. Please join me on this extraordinary journey, you won’t regret it.

It’s time for episode eight, listeners, and this is all about something I never thought I’d say in the same sentence as slime mold. The intelligence of slime mold is the eighth thing I like about this unbelievable organism.

We have established in previous episodes that slime mold has no brain, nor does it have any nerve clusters or ganglia of any kind that can organize impulses to indicate a creature that can make decisions, but this is exactly what slime mold can do.

Before we jump in, I want to touch on how slime mold travels. As you remember, there are two phases of slime mold, one is stationary and the second is mobile. The plasmodium is the mobile state of the slime mold. The plasmodium is a multinucleate mass of protoplasm that results from the fusion amoeba-like, motile cells. This is the feeding, creeping stage of this organism. They remain in this form when resources are abundant. This is the form that scientist study a lot and this is how we found out just how smart slime mold is. What exactly is it that makes us say slime mold is smart?

In the senses episode, we discovered that slime mold can smell food. They then pulsate in the direction of that food, but the really amazing thing is that it can choose the best food for them. In laboratory experiments, slime mold will reach out appendages in the different directions of offered food items. These food items are not the same quality. Slime mold, before even touching the food, will decide which one offers the best nutrition value and then concentrate its efforts on that food source. For a brainless organism that’s pretty amazing, can you believe that?

The next incredible feat of slime mold has to do with obtaining the food. When put into a maze with oats, slime mold loves oats, at both the entrance and the exit of the maze, this mold will stretch itself along the maze to find the shortest path in which it can eat both supplies of food at the same time! It can perform this amazing feat with 37 different points. To let you know, the number of possible ways to connect 37 points starts with an 8 and ends with 54 zeros. Slime mold can figure out the most efficient way to eat at all 37 points at the same time! I’m pretty sure I couldn’t do that.

Slime mold can also remember where they’ve been. In these food experiments, researchers noticed that the slime mold rarely retraced a previous path. They started to wonder if the slime mold was remembering where it had been? Turns out, it was. When it travels down a path it leaves behind slime, like actual slime, similar to a snail trail, that tells the mold it has already been there so don’t bother. Brilliant!

We’re going to stay in the realm of memory but throw in habituation. Have you heard of habituation? If not, habituation is when you get used to something you don’t like but doesn’t really hurt you. It’s like getting used to an annoying noise. Advanced organisms are great at habituation but what about slime mold? You got that right! Slime mold can habituate to adverse stimuli.

In a laboratory experiment, researchers placed oats on the other side of a bridge. To reach the food slime mold had to cross the bridge. Typically, the mold could reach the food in about a hour. Researchers placed salt on the bridge. Slime mold is not fond of salt. It doesn’t hurt it, that we can tell, but the slime mold doesn’t like it. This slowed the progress of the mold to ten hours, but once it got across the bridge it got the oats. It was rewarded with a treat for crossing the salty bridge. The next day the researchers repeated the setup. How would the slime mold react? Surprisingly, the slime mold crossed the salty bridge again but faster this time. The next day, the crossing time decreased again. The slime mold remembered that if it crossed the salty bridge it could reach the yummy oats, and essentially toughed it out, habituating itself to an adverse stimulus.

If none of this has convinced you that slime mold is out of this world, I’ve got one more for ya. Slime molds can teach other slime molds what it has learned! Take that in for a moment. After the salt experiment results, the researchers started to wonder if slime mold might be able to share this information. I mean, why not? This organism has broken all the other rules.

A little background here. If you take two slime molds and place them next to each other they will combine to make one slime mold. Over time, these researchers discovered that if they let slime mold that had learned to tolerate salt interact with other slime mold that had not habituated to salt for approximately three hours, the new slime mold tolerated salt without having to go through the habituation trials! My mind just exploded! Slime mold is essentially teaching other slime mold.

This organism surprises me every single episode! My eighth favorite thing about slime mold is its incredible intelligent abilities.

If you're enjoying this podcast please recommend me to friends and family and take a moment to give me a rating on whatever platform your listening. It will help me reach more listeners and give the animals I talk about an even better chance at change.

Join me next week for another fascinating episode about slime mold.

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This has been an episode of Ten Things I like About with Kiersten and Company. Original music written and performed by Katherine Camp, piano extraordinaire.