Did you know there’s an organism that doesn’t have a mouth but can eat, no limbs or muscles but can move, and no brain but can learn and pass on information to its offspring? It isn’t some exotic underwater oceanic being. You’ve probably already passed this physarum polycephalum while camping or walking through the woods. It is an amoeba, more commonly known as slime mold. The bright yellow glob is a huge, single-cell organism containing millions of nuclei. You can find it growing just about anywhere in the woods, ingesting bacteria, fungal spores, and other small protozoa. This mold has received a lot of attention since being displayed at the Paris Zoological Park in 2019. Many are calling this species “The Blob.'' It has baffled scientists, as it can’t be classified as a plant, animal, or fungus of the monophyletic grouping, which is a group of organisms descended from a single ancestor. Instead, Physarum Polysarum polycephalum is put into a polyphyly grouping, categorizing organisms that do not include a common ancestor. Think of it as a miscellaneous grouping humans need to organize the natural world. What makes this slime so interesting is its intelligence and ability to learn without evidence of a brain.
This species has been studied many times over the years, with some amazing discoveries. However, there are a few things that stand out to me:
- A few studies were conducted at Hokkaido University in Japan in 2010. One experiment was performed by placing the blob in a tray of agar, which is a jelly-like substance largely used in the laboratory to help both feed and grow bacteria. The idea was this blob would represent Tokyo, and researchers added 36 oat flakes representing the locations of other major cities in the area. The mold would then forage by sending out its branches (also known as plasmodia) from its central location to find all the oat flakes. This process can take a while, as it can only move a few centimeters an hour. The slime spread out as it sensed the food but, once located, it began to contract, leaving spindly veins of thicker, slimy branches that most efficiently connected the whole to the food. They compared these branches to the actual Tokyo Rail System; it was strikingly similar. The design process of the Tokyo subway system focused firmly on determining the most efficient routes possible. Something that took thousands of human engineers to work out was quickly and easily mapped out by an organism that has essentially no brain.
- Another study conducted at Hokkaido University discovered that physarum has event anticipation. They found this by making the environment of the physarum cold for 60-minute intervals. The mold anticipated the pattern and reacted to the expected conditions by shrinking. This result was recreated at 30 and 90-minute intervals.
- Studies have also been conducted utilizing mazes. Anyone can recreate it with the correct supplies. An oat flake is placed at the separate exits of the maze. The plasmodia expand and forage through the maze, finding the most efficient way to the food. It then contracts, leaving only the plasmodium plasmodia that has connected to the food. Here’s the cool part — it remembers the route. If the mold is taken out and placed in the maze later, it forms that same route to the ends.
- Researchers at the Centre on Animal Cognition published their study in 2016. These slime molds were trained to move past harmless substances that repelled them from their food. The study had 2,000 slime molds cross a bridge with salt, becoming habituated, while another 2,000 slime molds would cross a bridge without salt, making them the control. Once the habituated slime was trained, they were grouped into habituated, controlled, and mixed pairs. The slime molds would merge when they came into contact. The scientists then put the new, fused slime molds back to cross the salt-covered bridges. To their amazement, they observed the mixed slime molds moved just as fast as the habituated pairs, suggesting the slime shared the knowledge once they fused. It didn’t matter how many were merged together. As long as one habituated slime mold was part of the fusion, they were able to move across the salt-covered bridge quickly.
- “Monophyletic, Polyphyletic, & Paraphyletc Taxa.” Www.mun.ca, 2012, www.mun.ca/biology/scarr/Taxon_types.htm.
- “Brainless Slime Mold Organism Can Learn and Teach, Study Shows.” The Science Explorer, thescienceexplorer.com/nature/brainless-slime-mold-organism-can-learn-and-teach-study-shows. Accessed 2 July 2021.
- “Eight Smart Things Slime Molds Can Do without a Brain.” Www.pbs.org, www.pbs.org/wgbh/nova/article/slime-mold-smart-brainless-cognition/.
- “Slime Mould Attacks Simulates Tokyo Rail Network.” Discover Magazine, www.discovermagazine.com/technology/slime-mould-attacks-simulates-tokyo-rail-network. Accessed 2 July 2021.
- “Many-Headed Slime Mold.” Project Noah, www.projectnoah.org/spottings/7285929. Accessed 2 July 2021.
- “This Pulsating Slime Mold Comes in Peace (Ft. It’s Okay to Be Smart) | Deep Look.” YouTube, 19 Apr. 2016, www.youtube.com/watch?v=Nx3Uu1hfl6Q. Accessed 18 Dec. 2019. SciShow.
- “Slime Mold: A Brainless Blob That Seems Smart.” YouTube, 27 July 2017, www.youtube.com/watch?v=mOI-JlNcDVs. Accessed 29 Mar. 2021.
- “Slime Molds: When Micro Becomes Macro.” Www.youtube.com, www.youtube.com/watch?v=elqwn7k2Wwk.