Plasmodial Slime Molds

Ecology & Form

• Fungal-like protists, which are heterotrophic

  • e.g. Physarum

• Found in open forests, but also in extreme regions such as deserts, under snow blankets, or underwater

  • They also occur on the bark of trees, sometimes high in the canopy

• The structure is one large cell called a plasmodium, which is a macroscopic coenocytic mass without cells walls 

• When conditions are unfavorable for growth, slime molds create a sclerotium, which is an encrusting phase 

Reproduction

• May represent an ancestral protist with sexual reproduction (diplontic?)

• Spore cases (sporangia) are produced when conditions become unfavorable such as too warm, dry, or bright

• Through meiosis, spores are created, which germinates into a unicellular amoeba-like cell or a flagellated cell

• These "gametes" fuse with another in plasmogamy, and then kayogamy to create a zygote (amoebozygote)

• Through mitosis, the zygote grows into a plasmodium once again

Classification

Unikonta - single-flagellum organisms

 └Amoebozoa - amoeba-like organism

    └Mycetozoa - slime molds

       └Myxomycota - plasmoidal slime molds