Fungus-like Protists

FUNGUS-LIKE PROTISTS

similar to fungi in appearance and mode of nutrition

non-photosynthetic and undergo a particular stage in their life cycle that is mold-like

Slime Molds

spend most of the life cycle as free-living, amoeba-like cells (phagocytic)

found near rich sources of food (e.g. rotting wood, piles of compost, thick wet lawns)

when nutrients are scarce and cells are starving, many of the cells aggregate (coenocytic) and form a slimy mass that may migrate to a more favorable location; which will later on form a spore-bearing structure; when conditions improve, the spores germinate, starting the cycle again

Coenocytic

 Phylum Myxomycota

acellular or plasmodial slime moldsthe plasma membranes and cell walls of the

aggregated amoebas break down, forming one large cytoplasmic mass (multinucleate) which is the feeding stage

the mass (plasmodium), which can be several square meters in size, migrates and then forms spores

when conditions become unfavorable, the plasmodium “fruits”, forming a spore-bearing fruiting body which produce haploid spores by meiosis

spores scatter to the ground where they germinate into flagellated gametes which fuse to form a diploid zygote (sexual reproduction) that undergoes mitosis to produce diploid ameboid cells

e.g. Physarum

Physarum

Phylum Acrasiomycota

cellular slime moldswhen the cells aggregate (pseudoplasmodium),

they adhere to one another but remain separated by their cell membranes

this aggregation creates a slug-like form, which migrates in search of a place to form a fruiting body (reproductive structure) which produces spores by mitosis

reproduction is asexual; no diploid stage in the life cycle

e.g. Dictyostelium discoideum