Original photo by Mantonature/ iStock
Slime molds, sometimes affectionately referred to as “The Blob,” defy scientific explanation — literally. They’re not plants, animals, or even fungi (as scientists believed before DNA sequencing came along). Instead, slime molds are considered protists, which one scientist describes as a catch-all term for “everything we don’t really understand.” Slime molds also defy our understanding of sex, since they are capable of assuming more than 700 different sexes depending on their genetics. They even complicate our ideas about intelligence. Alone, slime molds are simple single-celled creatures, but together they form a complex network that can remember and exhibit plenty of smarts.
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It's a fibAlthough slime molds perform impressive feats in a group, alone they are just a single-celled organism — none of which have nervous systems. Nervous systems are more common among multicellular organisms; only the sea sponge and a few microscopic multicellular organisms lack them.
For example, slime molds such as Physarum polycephalum are expert maze solvers. They approach a maze completely differently than your average human, who might start out on one path only to hit a dead end, backtrack, and then test another path. A slime mold, on the other hand, spreads itself over the entire surface of the maze and then reorganizes its body, leaving behind the most efficient path to get from point A to point B. Of course, slime molds didn’t start out by solving mazes for fun or science: In the wild, Physarum polycephalum has evolved to spread out its pseudopodia — a network of tube-like tendrils — to locate food such as bacteria and fungal spores. Once the food has been found, the slime mold creates the most efficient pathway to that food possible — all without a brain or nervous system. Scientists can still only theorize about how slime molds transport information along their bodies. And although they’ve oozed around the planet for perhaps a billion years, slime molds are only recently getting the respect they deserve. In 2019, the Paris Zoo created an exhibit celebrating the slime mold, a decision that went viral and captured the attention of the world. Well, better late than never.
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The branch of science that studies fungi and molds is ______.
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The branch of science that studies fungi and molds is mycology.
The U.S. highway system is slime mold-approved.
Slime molds seem like simple creatures, but in some ways, they’re smarter than humans. That’s why scientists have recruited slime molds to review human-made systems — chief among them transportation. In 2012, scientists created a large dish the shape of the United States and placed rolled oats (a favorite of the slime mold Physarum polycephalum) in the approximate location of 20 major metro areas. Once let loose, the slime mold essentially recreated the U.S. highway system. From its point of view, Interstate 10 and 20 were the system’s backbone, connecting East and West. While the U.S. passed the slime mold test, it wasn’t the most efficient country. The same researchers discovered that Canada’s highways make even more sense, and Japanese researchers almost perfectly recreated Tokyo’s rail network using a slime mold. What humans took decades to design, a slime mold figured out in hours.
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
