Scientist's Pick: Smart Slime

By Staff Scientist on January 29, 2010 3:31 PM

Note: This month's "Scientist's Pick" is from Science Buddies' staff scientist, David Whyte. David presented this project to the Science Buddies' team last fall. It's very cool! ~ Science Buddies' Editorial Staff

Project: Smarter Than Your Average Slime: Maze-solving by an Amoeboid Organism
Scientist: David Whyte
Science Buddies' Difficulty Level: 7-9

I was doing some background research on simple organisms that might be used in science projects when I came across an article entitled "Maze-solving by an amoeboid organism." The article contained just what I had been looking for—the basis for a novel project that was both cutting-edge science and also well within the reach of the kitchen scientist.

Materials Tip!

Kits for growing the organism, Physarum polycephalum, can be purchased from several science supply stores online.

The basic finding of the research presented in the article was that Physarum, a common inhabitant of wooded areas around the world, can find the shortest path through a maze set up on an agar plate. Physarum, also called slime mold, typically forms a large amoeba-like mass that moves over dead leaves and rotting logs looking for organic matter to consume.

Announcing their findings in the journal Nature, the researchers said they believe the organism changed its shape to maximize its foraging efficiency and therefore its chances of survival. They went on to claim that "This remarkable process of cellular computation implies that cellular materials can show a primitive intelligence."

In the lab, Physarum can be grown in Petri dishes that have a layer of agar on the bottom, so I decided to put Physarum to the test at home.

Conducting the Experiment

To set up the experiment, I placed pieces of slime mold in a 30-square-centimeter (five-square-inch) maze on an agar plate. On that same plate, I strategically placed a food source at two spots in the maze.

What happened?

The pieces of slime mold coalesced, and the organism condensed its entire body to form a mass that stretched between the two food sources and connected them. In each trial, the slime mold showed its ability to both solve the maze and find the food. Each time, it adopted the shortest possible route, effectively solving the puzzle.

The project idea I created for Science Buddies lets you devise your own maze to see for yourself how the slime mold behaves. You'll have to decide for yourself—is the slime mold "intelligent"? Are there limits to its intelligence?

Other questions you might ask as you work with the Physarum include:

What environmental cues is it using and how does it process information in ways that allow it to adapt?

What other tests can be devised to further explore how these remarkable creatures respond to the world as their senses experience it?

For me, any project that involves "cellular computation" and "primitive intelligence" in an amoeboid organism has lots of potential. In this project, what I discovered is that Physarum is a simple organism - one that you can experiment with at home—but it is not really so "simple" after all.

David