Slime moulds have baffled taxonomists for centuries. In about 1750 when Carolus Linnaeus devised his binomial system of classification he created three kingdoms: animal, plant and mineral. Fungi – along with the ‘fungus-like’ slime moulds – were included in the plant kingdom.
With the advent of the microscope in 1665 and its improvement and use in botanical studies over subsequent years, it was clear that fungi lack the cells found in plants and they don’t photosynthesize; the kingdom fungi was created 1784. Because slime moulds, like fungi, reproduce by spores, they were also moved to the fungi kingdom.
In 1833 German naturalist and botanist Johann Link perceived slime moulds as different from fungi and created the name myxomycete (Gk myxo slime; myketes fungi).
The motile feeding stages of slime moulds were emphasised for including them in the kingdom animalia and then the kingdom protista. They are currently classified as Amoebozoans.
Acellular Slime Moulds – the most remarkable organisms. ‘Slime mould’ is not a term that elicits excitement in most people, nor does it conjure up images of great beauty. But slime moulds must be among the most remarkable of organisms. At one stage of their life they are single cell amoebae, whose definition is found in the Dictionary of Zoology, then they combine with other compatible amoebae to form a plasmodium-or pseudoplasmodium-defined in the Dictionary of Plant Sciences.
Myxomycetes: plasmodial or acellular slime moulds
One of the most frequently encountered acellular slime moulds is Fuligo septica whose common names of either ‘dog vomit’ or ‘scrambled egg’ slime mould evocatively describe its size and consistency. It appears on rotting logs, stumps or live vegetation in the warmer months, first as moist, bright yellow amorphous blobs. As the spores develop, the outer covering, the cortex, gradually hardens and the yellow fades. It is likely, given that many acellular slime moulds have a cosmopolitan distribution, that it was the one featured in 9th century Chinese writings called ‘Kwei hi’ which translates to ‘demon droppings’. In an area of Mexico the plasmodium is fried and eaten by some of the indigenous people who call it ‘caca de luna’, i.e. ‘moon shit’. There is a common misconception in Tasmania, perpetuated by people who work or live close to forested areas, that Fuligo septica is ‘snake poo’.
What really got me hooked was finding clusters of exquisite 4 mm high fruiting bodies resembling tiny purple mushrooms on a dogwood (Pomaderris apetala) log that had been lying on swampy ground for years, possibly decades. After checking a few web sites I identified it as Arcyria denudata but have since learnt that there are several pinkish-red Arcyria species and that microscopic examination is necessary to tell them apart. I replaced the slime mould in a shady spot and planned to make regular visits to record its progress. As luck would have it, there was another Arcyria species (Arcyria obvelata) about a metre away.
I have learnt quite a bit about slime moulds since that encounter with the purple Arcyria. For instance, they are apparently very sensitive to disturbance (they don’t like rough handling, but they don’t seem to mind loud exclamations of delight on being discovered!) and although a few of the fruiting bodies on the sodden dogwood matured, I lost track of most of them and presume they did not cope well with being moved.
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