Slime Moulds
Although the Slime Moulds or Acrasiomycota are not considered part of the fungal kingdom any longer, they are usually the object of study of fungal biologists or mycologists because they spread by means of spores which develop in reproductive organs similar to sporangia or aethalia, resembling fruit-bodies of fungi. Nowadays the nearly 500 species of Slime moulds together with the unicellular amoebas (Class Lobosea) form the Phylum Rhizopoda, which together with many other phyla of micro organisms with a nucleus like the ciliates, (dino) flagellates, diatoms, red and brown algae distinguish themselves from all other life forms as the Protoctista Kingdom.
Mycroscopically small, creeping or swimming initial stages resembling amoebas (or myxamoebas) or flaggelates (or myxomonads) hatch from spores. Subsequently, the myxamoebas develop into a horizontally or vertically mobile stage, the plasmodium, and finally become a fixed stage with fruit-bodies in which the spores develop. Spores may spread over long distances.
The creeping mass of plasma, which feeds on micro-organisms such as bacteria and on fungal spores and hyphae, the so-called plasmodium, usually leaves a shiny, mother- of-pearl-like trail (48.jpg) with food remains on or in the substrate.
Several slime moulds have a somewhat more voluminous and compact, often brightly coloured plasmodium from which one or more stipeless fruit-bodies or aethalia develop (42.jpg). Most Myxomycetes have a strongly veined plasmodium, spreading fan-like and growing like a net, which moves in ‘ streams’ over or in the substrate (44.jpg).
Under unfavourable conditions, a plasmodium can contract, the internal parts will then be provided with a firm wall and sclerotia will develop.
After sufficient food intake and occasionally under the influence of light, a plasmodium will proceed to form one or more large or small fruit-bodies.
If the plasmodium contracts into a number of seperate lumps, separate, stemmed fruit-bodies or sporangia will be produced.
The sporangia which continue to develop are often concolorous with the plasmodium (45.jpg).
Occasionally a stipe is formed first, after which the plasmodium creeps upwards in or along a hollow stipe and assumes its final sporangium shape. When ripening, the fruit-bodies often change colour. The spores develop on the stipe and within the wall of the peridium of the fruit-body. The surrounding membrane ruptures, after which the (nearly) round spores, measuring 5-20 micron in diameter, are spread by wind and rain drops in red-brown or purple-brown to brown-black clouds (46.jpg).
Listed taxa:
Order Liceales:
(Family Reticulariaceae)
- Lycogala epidendrum
- Enteridium lycoperdon
- Dictydiaethalium plumbeum
- Tubifera ferruginosa
Order Physarales:
(Family Physaraceae)
- Physarum vernum
- Badhamia utricularis
- Leocarpus fragilis
- Fuligo septica, Yellow Slime Mould
(Family Didymiaceae)
- Didymium serpula
Order Trichiales:
(Family Trichiaceae)
- Arcyria denudata
Order Ceratiomyxales:
- Ceratiomyxa fruticulosa var. fruticulosa