What Are Myxomycetes?
Estimated Time: 10–15 minutes
Course: Myxomycetes 101 — Introduction to Slime Molds
Lesson Type: Reading + Media (self-paced)
1. Welcome to the World of Slime Molds
Slime molds—formally known as Myxomycetes—are among nature’s most misunderstood organisms. They look like fungi, move like animals, and belong to a group of single-celled amoeboid organisms called Amoebozoa.
Yet, despite their humble size, they’ve captivated scientists, photographers, and naturalists for over two centuries.
Taxonomic Snapshot
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- Domain: Eukarya
- Supergroup: Amoebozoa
- Class: Myxogastria (Myxomycetes)
Arcyria denudata — “Myxomycetes often form delicate fruiting bodies only 1–2 mm tall.”
Key Takeaway: Myxomycetes are not fungi, but amoeboid protists that feed on bacteria and organic matter. They play an important ecological role as decomposers in forests and other moist habitats.
2. The Life Amazing: Amoebas, Plasmodia, and Fruiting Bodies
A myxomycete’s life cycle is a shape-shifting marvel. It begins as a microscopic amoeba, fusing with others to form a plasmodium—a visible, multinucleate mass that can move, feed, and explore its environment. When conditions change, the plasmodium transforms into stunning fruiting bodies, producing spores that disperse and begin the cycle anew.
Watch a plasmodium grow and form fruiting bodies — a mesmerizing look at nature’s micro-engineering.
Did You Know? Myxomycetes can solve mazes, map efficient networks, and even learn from past experiences — despite having no brain or nervous system!
3. A Brief History of Discovery
The story of slime molds is one of scientific reclassification. In the 1700s, naturalists mistook them for fungi because of their spore-bearing structures. By the 1800s, researchers such as Ehrenberg and de Bary realized they were something different — part fungus, part protozoan — and coined terms like Mycetozoa (“fungus-animals”).
With the rise of molecular biology in the late 20th century, DNA analysis finally revealed their true home: the Amoebozoa, alongside free-living amoebae and cellular slime molds.
Timeline Callout:
- 1654: The first account of a slime molds was by Thomas Panckow in his discussion of Lycogala epidendrum.
- 1729: Pier Antonio Micheli thought that fungi are different from molds.
- 1829: Elias Magnus Fries documents the plasmodial stage.
- 1833: Heinrich Friedrich Link agreed with Pier Antonio Micheli’s hypothesis.
- 1864: Anton de Bary observed the germination of the spores.
- 1874 to 1876: Józef Tomasz Rostafiński, a student of Anton de Bary, published the first extensive monograph on the group.
- 1894, 1911, & 1925: Three monographs by Arthur Lister and Guilielma Lister were published.
- 1969: Myxomycetes by George Willard Martin and Constantine John Alexopoulos.
- 1960s–1980s: Studied for cellular movement and decision-making.
- 2000s: Molecular data confirm they are amoeboid protists.
Why It Matters: Understanding their classification reshapes how we study biodiversity and evolution — showing how complex behavior can emerge in single-celled organisms.
4. Slime Molds vs. Fungi: What’s the Difference?
| Feature | Myxomycetes | Fungi |
|---|---|---|
| Kingdom | Protista (Amoebozoa) | Fungi |
| Feeding | Phagocytosis (engulfs prey) | Absorption (secretes enzymes) |
| Cell Walls | None in plasmodium | Chitin walls |
| Movement | Amoeboid movement | None (stationary) |
| Life Cycle | Amoeba → Plasmodium → Fruiting body | Hyphae → Mycelium → Fruiting body |
| Appearance | Brightly colored sporangia | Typically duller spores and hyphae |