Knowledge

What is Physarum polycephalum?

Physarum polycephalum is the scientific name of your slime. It’s a type of slime mold, a simple living organism that is not a plant, animal, or fungus, but something else called a protist. It lives in cool, damp places like forests, where it feeds on tiny bits of organic matter, bacteria, and fungi. Even though it looks like a yellow blob, it can move, grow, and even solve simple problems in its environment.

Regardless of how big it gets, your slime will remain a single cell, a fact that has made P. polycephalum the focus of a lot of research! Unlike most cells, P. polycephalum just keeps adding more and more nuclei (and the rest of the organelles a cell needs) as it grows instead of dividing into more cells. Nuclei are the information centers of cells, storing the instructions for building and operating all the different parts of the cell. Many of those parts are called organelles, and they’re like the cell’s organs.

The Life Cycle of Physarum polycephalum

Physarum polycephalum goes through several stages during its life. Each stage helps it survive in different conditions. While most organisms progress through their life cycle with time, P. polycephalum can stay in each life cycle stage indefinitely until it is triggered into another by an outside stimulus. Additionally, many of its life cycle stages are reversible, so it’s helpful to think of the stages as modes more than a linear progression.

1. Spores

The life cycle begins with spores, which are tiny particles similar to seeds. Spores can stay inactive for a very long time. When they land somewhere moist and comfortable, they can germinate (wake up).

2. Amoebae or Flagellated Cells

When a spore germinates, it produces a small single cell. These cells come in two forms:

  • Amoebae, which crawl along surfaces, or
  • Flagellated cells, which can swim in water using a tail-like structure.

These little cells feed on bacteria and continue growing until they meet another compatible cell, then they fuse and grow into a plasmodium (more on that below).

3. Cysts

In unfavorable conditions, like the environment drying, getting too hot or cold, or lacking food, the amoebal and flagellated cells can transform into cysts.

Cysts are tough, dormant cells a lot like spores. They can remain dormant for extended periods and reactivate when conditions are favorable to become either amoebal cells or flagellated cells once again.

4. Plasmodium

When two compatible cells join together, they form a larger structure called a plasmodium. This is the stage most people recognize: a bright yellow network that looks like a branching slimy blob.

The plasmodium is one giant cell with many nuclei. It moves slowly across surfaces in search of food and connects different food sources with efficient pathways.

5. Sclerotium

If the environment becomes too dry, too hot, or lacks food, the plasmodium can turn into a sclerotium.

This is a dry, hardened form that helps the organism survive tough conditions. The sclerotium can stay dormant for months or even years. When moisture returns, it can reactivate and return to the plasmodium stage. This is the stage you receive in the sleeping slime hibernation capsule with your Slime-O Worlds kit!

6. Sporangia

When conditions like sunlight and diminishing food sources tell P. polycephalum it’s time to reproduce, it forms fruiting bodies. These structures are sporangia (little spore containers) that look kind of like burnt popcorn on the end of an orange-yellow stalk! Inside them, new spores develop. When the fruiting bodies release their spores, the cycle starts all over again.

Fun facts

  • They’re not fungi!
    • Despite looking like fungi and sometimes being called “slime molds”, myxomycetes are actually protists; neither a mold nor a fungus, they are in fact a type of amoeba.
  • They’ve inspired computer algorithms.
    • Scientists modeled myxomycetes foraging behavior to design and predict efficient transportation and network systems, including Tokyo’s subway layout!
  • They are one giant cell.
    • The slime you see in this kit is a single GIANT cell containing thousands (or even millions!) of nuclei all sharing one big soup of cell goo, called cytoplasm. This is a very unique life cycle stage seen only in myxomycetes. This living slime is called a plasmodium.
  • They move in slow motion.
    • Myxomycetes can creep across surfaces at speeds of up to 1 centimeter per hour, leaving slimy trails behind.

Nakagaki, T., Yamada, H. & Tóth, Á. Maze-solving by an amoeboid organism. Nature 407, 470 (2000). https://doi.org/10.1038/35035159

  • They can solve mazes.
    • In lab experiments, plasmodial myxomycetes found the shortest path through a maze to reach food… Without a brain!
  • They have “memory” without neurons.
    • They can “remember” where they’ve been by sensing chemical residues they left behind, helping them avoid revisiting depleted areas.
  • They can fuse and share information.
    • Two compatible myxomycetes that meet can merge into one mega-organism and share learned behaviors. Compatibility depends on complex interactions between hundreds of different factors, but all the specimens provided in Slime-O Worlds kits are fusion-compatible!
  • They can regenerate after being cut.
    • Slice a plasmodium apart, and the fragments can grow and fuse back together later as if nothing happened.
  • There are more than 900 known species.
    • They live almost everywhere; from rainforests to deserts, even in your backyard.
  • They’re bright and beautiful.
    • Myxomycetes come in dazzling colors like yellow, orange, red, blue, or pearly white, often used by photographers for macro art. Physarum polycephalum, the species of myxomycete in our kits, is bright yellow to slightly orange; the exact shade depends on the pH of its habitat!
  • They sporulate.
    • When food runs out, myxomycetes can transform into fruiting bodies (a process called sporulation) that release spores, tiny survival capsules that can last for years and mark the beginning of their life cycle. Most will need to fuse with another cell before they can grow into a plasmodium.
  • They can “freeze and wake up.”
    • A dried-out plasmodial myxomycete, called a sclerotium, can survive months or even years in dormancy, then “come back to life” when moistened again.
  • They eat bacteria, spores, yeast, and plant matter.
    • Myxomycetes are nature’s tiny recyclers, feeding on decaying material and microorganisms in forest litter. In captivity, they also love grains like oats and rice!
  • They can navigate complex environments.
    • When placed between food sources, plasmodia distribute themselves in patterns that mirror efficient networks, like neural networks and road systems.
  • They “breathe” like us.
    • Myxomycetes use oxygen and give off carbon dioxide, a trait they share with animals, not plants.
  • They’ve been to space!
    • A sister of the exact specimen in your Slime-O Worlds kit actually went to space on a NASA launch! Astronauts took a dormant sclerotium to the International Space Station and awakened it onboard to study its growth patterns in microgravity. When not pulled to the ground by gravity, the slime grew three-dimensionally, expanding up, down, and sideways effortlessly! Slime-O-nauts!
  • They are master escape artists.
    • Plasmodia are capable of crawling through holes smaller than pin pricks by forming a tiny channel and slowly pumping their entire cell mass through it to the other side!
  • They’re ancient creatures.
    • By what we can tell from fossils, myxomycetes are much older than dinosaurs; the exact species you grow in this kit, Physarum polycephalum, roamed the Earth alongside Triceratops, Spinosaurus, Brachiosaurus, T. rex, and the like, but was their elder by many, many years.