Ever seen the 1958 horror classic, “The Blob”? Well that movie is actually based somewhat in reality. Our planet is swarming with over 900 species of mini “Blobs” as we speak. They’re not animals, they’re not plants, and they’re not even a type of fungus. These suckers are slime molds and they belong to a group of their very own called Myxomycetes – the amoeboid protists.
Basically what they are is a giant unicellular organism containing thousands of nuclei as a result of a swarm of single cells that fused into one. Slime molds make their homes in any place from forest floors, lawns, moldy gutters, to their own special cages in laboratories. They feed on decaying vegetation, bacteria, and fungi that they “chase” down and engulf by sending out protoplasmic strands that move via cytoplasmic streaming. This essentially means that they shift their cell contents forward and grow toward a target as the trailing end’s growth is restricted and starts to recede. This behavior has become extremely popular to study among scientists because of the ease of observation thanks to the slime mold’s large size. The movement can even be seen with the naked eye. Their growth patterns can be manipulated and studied using a trail of oatmeal flakes, which in its own, really creepy way, is kind of charming. I have actually done this myself with a Physarum polycephalum (the most commonly studied lab slime mold). They will follow the trail to create some of the most intricate patterns imaginable for a slime.
They seem to also possess some sort of seemingly sentient problem solving ability because, when placed in a maze, they will restrict their growth to the shortest, most direct path to food placed at the other end on the very first trial. They can also apparently anticipate periodic events. There was even an experiment done by Klaus-Peter Zauner at the University of Southampton in the UK that involved a P. polycephalum controlled robot. The slime mold was grown in a six pointed star formation on a circuit and connected remotely with a computer to a six-legged robot. Each of the six points controlled a leg of the robot. Slime molds hate bright light, so when exposed to that, it tried to get away. The robot sensed the slime’s movement and it tried to scuttle away from the light too.
The hexapod robot controlled by P. polycephalum. Credit: Klaus-Peter Zauner
There is also now evidence that slime molds may possess a form of memory, though they have no brain. They are able to recognize their own trails and know where they have been and where they have not. This was tested by researchers who placed several of our friends, P. polycephalum, into a U-shaped trap. When the trap was untreated with paths of slime, 96% of P. polycephalum were able to easily navigate through to get to the sugar water at the other end before their 120 hour time limit was up. After the trap was coated with slime, however, only a third of the molds reached the sugar water before time ran out and had great difficulty making it back to the beginning again.
If all of that brainless problem solving and memory weren’t enough, slime mold has recently become a hero to astronomers and computer scientists for helping to create a computational model to visualize the cosmic web connected by dark matter. This new model is based on the growth pattern of the ever useful P. polycephalum and appears to be the most accurate model of the interconnectedness of the universe to date. In addition to helping solve some of our greatest cosmic mysteries, slime mold has been able to replicate the Tokyo railway almost perfectly, following oat flakes representing Japanese cities. It took engineers hours upon hours to create something that a slime mold did effortlessly in just over a day.
A slime mold begins as a single cell and once it encounters food or a compatible zygote, it multiplies to become the giant slime cell that is most commonly seen. At the end of a slime’s life cycle, which happens when conditions become unfavorable, it forms rigid clusters of spores known as sporangia or fruiting bodies. These spores are eventually released and travel to new locations to start the cycle over again.
Now that you know more about slime molds, let’s take a look at a few individuals.
Fuligo septica.
As the scientific name suggests, this one is particularly disgusting. It is more commonly known as the dog vomit slime mold and is one of the largest species.
This is our much less offensive little robot controller up there and the kind I had the, uh, pleasure (?) of growing.
Physarum polycephalum. Credit: Dru!
Many of them are actually quite colorful and magical looking.
Diachea leucopodia. Credit: Carlos de Mier
Metatrichia vesparium. Credit: Katja Schulz
Ceratiomyxa fruticulosa. Credit: Ryszard
Tubifera ferruginosa
I hope you found this interesting and now I’ll just leave you with a rather prophetic quote from biologist Chris Reid, one of the researches who experimented with slime mold memory: “I, for one, welcome our new gelatinous overlords.”
References:
1. Ling, Hubert. “Myxomycetes: Overlooked Native Plants.” The Native Plant Society of New Jersey. The Native Plant Society of New Jersey, 2012. Web. 19 Apr. 2015. .
2. Knight, Will. “Robot Moved by a Slime Mould’s Fears.” New Scientist. New Scientist, 13 Feb. 2006. Web. 19 Apr. 2015. .
3. Tsuda, Soichiro, Klaus-Peter Zauner, and Yukio-Pegio Gunji. “Robot control with biological cells.” Biosystems 87.2 (2007): 215-223.
4. Ingber, Sasha. “Slime Has Memory but No Brain.” National Geographic, National Geographic Society, 12 Oct. 2012. Web. 19 Apr. 2015. .
5. Reid, Chris R., et al. “Slime mold uses an externalized spatial “memory” to navigate in complex environments.” Proceedings of the National Academy of Sciences 109.43 (2012): 17490-17494.
6. Stephens, Tim. “Astronomers Use Slime Mold Model to Reveal Dark Threads of the Cosmic Web.” UC Santa Cruz News, 2020, news.ucsc.edu/2020/03/cosmic-web.html.
7. Wogan, Tim. “Ride the Slime Mold Express!” Science, AAAS, 21 Jan. 2010, http://www.science.org/content/article/ride-slime-mold-express. Accessed 13 Aug. 2023.
Photo Links:
1.Slime mold robot
The Occasional Creature Fact 
