Slime Molds Facts and Examples

Bridget Curran, Sarah Phenix
  • Author
    Bridget Curran

    Bridget is completing her M.S degree in Biology at Plymouth State University and received a B.S degree in Biology with a minor in Chemistry from Castleton University. She has experience teaching biology and botany for three years at Plymouth State University.

  • Instructor
    Sarah Phenix
Learn what slime mold is and get slime mold facts. See examples of different types of slime molds and read about slime mold reproduction and life cycles. Updated: 02/16/2022

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What is a Slime Mold?

What is slime mold? Slime Molds are single-celled eukaryotic organisms. The slime mold kingdom is Protista (Protist). There are several slime mold characteristics. They feed on yeast, bacteria, fungal spores, and other protists. Slime molds live as single-cell organisms or aggregate together to form multicellular organisms. The slime mold scientific name is Mycetozoa. They can range in size from a few centimeters to several square meters. When food sources are available, slime molds exist as single-celled organisms. When food is scarce, slime molds aggregate into colonies. There are an estimated 900 species in existence that occupy a wide range of habitats from forest floors, soil, logs, and temperate or tropical regions.


Fuligo septico

Fuligo septico


Slime Mold Kingdom and Taxonomy

For many years, the slime mold kingdom was considered Fungus. Today, because of advancements in phylogenetics, slime molds are now classified as Protists. Phylogenetics is the study of evolutionary history and relationships among organisms. Researchers use DNA and morphology (physical characteristics) to study the origins and evolutionary trajectory within and among organisms. Protists and slime molds are polyphyletic. Polyphyletic means they are derived from more than one common ancestor. Essentially, protists are eukaryotic organisms that are not plants, animals, or fungi. Eukaryotic refers to organisms with cells that contain a nucleus. Other examples of protists include amoebas, diatoms, and dinoflagellates.

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  • 0:00 Introduction to Slime Molds
  • 0:39 Background on Protists
  • 1:39 Definition of Slime Molds
  • 2:36 Why Isn't Slime Mold a Mold?
  • 3:47 Types of Slime Molds
  • 4:27 Lesson Summary
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Slime Mold Life Cycle and Reproduction

The two main distinctions of slime mold life cycle and slime mold reproduction are plasmodium slime molds and cellular slime molds. The next two sections will go over specifically what occurs in each of these, followed by examples of types of slime molds.

Plasmodium Slime Molds

Plasmodium slime molds are typically brightly colored and form a large mass as they grow called a plasmodium. Plasmodium is a single-celled mass consisting mainly of cytoplasm with undivided plasma membranes that contain multiple nuclei. The multiple nuclei are produced by mitotic cell divisions without cytokinesis. Cytoplasm is the gelatinous substance that fills the inside of cells. Cytokinesis is the division of the cytoplasm in cell division. The plasmodium forms and extends pseudopodia which extends through the various substrate the plasmodium is living on (leaf litter, rotting wood, decaying plant matter, soil). The pseudopodia engulfs food matter through phagocytosis. Phagocytosis is the process by which a cell engulfs food particles. When food becomes scarce, the plasmodium forms fruiting bodies for sexual reproduction. The following describes the steps included in the plasmodium life cycle and reproduction.

  1. Plasmodium feeds through phagocytosis.
  2. Fruiting bodies are formed when food becomes scarce. Fruiting bodies are called sporangia.
  3. Sporangia produces haploid spores through meiosis which are then released into the environment.
  4. In suitable conditions, spores germinate and release motile haploid cells.
  5. Cells are either amoeboid or flagellated and fuse together to form diploid zygotes.
  6. Nucleus of diploid zygote undergoes cell division without cytokinesis, forming a new plasmodium.

Cellular Slime Molds

Cellular Slime Molds exist as single-celled, solitary organisms. When food becomes scarce, a chemical is released which signals other cellular slime molds to begin to aggregate to form an aggregate slug. The aggregate slug is a multicellular organism, separated by cellular membranes, unlike plasmodium. The following lists the stages of the life cycle and reproduction of cellular slime molds.

  1. Single, haploid cells feed by engulfing bacteria.
  2. Two haploid cells fuse to form a diploid zygote.
  3. Diploid zygote grows by absorbing other haploid cells, develops a wall, undergoes meiosis and mitotic divisions.
  4. When the wall ruptures, new haploid cells are released.
  5. When food is scarce, new haploid cells aggregate to form an aggregate slug.
  6. Slug migrates until a stalk is formed by stacking of haploid cells, and a fruiting body is formed on top of the stalk.
  7. Some cells migrate to the top of the stalk and develop into spores which are released into the environment.
  8. Haploid cells release from the spores.

Slime Mold Types and Examples

There are multiple types of slime molds. Slime molds are often classified as being plasmodium slime molds or cellular slime molds. Within these classes, they also are distinguished by their life cycle and reproductive phases, habitat type, and morphology (physical characteristics). Below are several slime mold examples.

Myxomycetes

The slime mold scientific name is Mycetozoa. One of the largest classes of slime molds is Myxomycetes, with 888 species and referred to as true slime molds. During the vegetative phase (asexual phase). Myxomycetes form plasmodium. In the reproductive phase, the plasmodium forms a fruiting body and releases spores through the sporangia (mentioned above). Myxomycetes exhibit a wide range of morphologies. The plasmodium can range in color from yellow, green, white, black, clear, depending on the species. In some species, the plasmodium will form puffballs. Fruiting bodies will also vary in morphology. Myxomycetes are found in a wide range of habitats all over the globe from forest floors of temperate and tropical forests. Myxomycetes also include a few cellular slime molds as well.


Lycogala_epidendrum

Lycogala epidendrum



Fruiting bodies of Comatricha elegans, species in Myxomycetes

Fruiting bodies of Comatricha elegans


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Frequently Asked Questions

How fast does slime mold grow?

The rate at which slime molds grow is dependent on the species. Some plasmodium can move up to several feet in 24 hours.

What defines a slime mold?

Slime molds are eukaryotic single-celled organisms in the kingdom Protista (Protists). Protists are essentially, anything that is not a plant, animal, or fungus.

Is slime mold harmful to humans?

No, slime molds are not harmful to humans. Unlike their name suggests, slime molds are not considered mold or fungi.

What causes slime mold?

Slime molds exist everywhere on earth but the vast majority are found on forest floors, soil, logs, temperate or tropical habitats. When food becomes scarce, the slime molds will aggregate to form aggregate slugs or plasmodium, which can be visible without a microscope.

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