What are slime moulds?
The strange, sometimes colourful blobs we often see on lawns, mulch, logs, gardens, and forests, were once thought to be fungi, and are often referred to as myxomycetes ('fungus animals'), even though they are neither!
Slime moulds belong to the amoebozoa (Burki et al. 2020), a group which includes forms of life such as amoeba. They are split into two groups, the acellular (plasmodial) and the cellular slime moulds. The slime moulds we see in the forest are plasmodial slime moulds - and when they are in the 'blob' stage they are displaying the plasmodial part of their life cycle.
Around 900 or more species of slime moulds are thought to occur worldwide. Feeding on a variety of things, slime moulds munch on bacteria, decaying organic matter and fungi by engulfing and by excreting enzymes which help make the food easily digested by the slime mould (Keller & Everhart 2010).
Where can I find slime moulds?
Slime moulds are found worldwide, from tropical rainforests to the cold conditions of the sub-Antarctic. Slime moulds are most abundant in the moist, temperate forests of the world (Lloyd 2018).
Any time of year can be a good time for finding slime moulds as long as the conditions are right. Their often bright colours capture the attention of those passing by as they appear on manure and mulch in parks and gardens after rain.
You may also find slime moulds in areas with more vegetation, such as forests, where on the underside of moist, well rotted logs, tree stumps of native and exotic trees, bark, leaf litter, dung, ferns and mosses. Exotic trees including oak, elm, birch and cultivated apples can be good substrates to find slime moulds (Keller & Everhart 2010).
If you get up early in the morning, you may find fresh slime moulds as fruiting bodies are said to be usually produced at night or in the early morning releasing spores (Lloyd 2018).
What a difference a day can make! Move your mouse over the image to see!
DAY 1
Fuligo septica - Dog Vomit Slime Mould
Image showing the aethalium, a relatively large, stalkless, rounded fruiting body formed from all or most of the plasmodium.
DAY 2 Fuligo septica Dog Vomit Slime Mould - transforms to crusty sclerotium.
SLIME MOULD LIFECYCLES
Plasmodial Life Cycles and Looks
Just like humans, Slime moulds may look very different depending on environmental factors and stage of growth they are at! Slime moulds are said to display 'phenotypic plasticity' whereby they look different or change behaviour when environmental factors alter. For example, when a slime mould is in the plasmodial stage of it's lifecycle, they can look like gooey, slimy, blobs, stationery on the forest floor. If conditions change, for example, a lack of moisture or food, the plasmodia can convert to a hardened, crusty, dormant structure called a sclerotium, until conditions improve.
Slime moulds are able to remain dormant for some years (Lloyd 2018).
Myxomycetes on the Move - Don't let that blob fool you!
In the plasmodial stage of their life cycle, Slime moulds may look like blobs just sitting there, but in this stage, they may creep across the forest floor through use of a pseudopodia (from the greek roots pseudo-false, podos-foot), which may allow them to travel several metres across the forest within days and feed on bacteria, fungi and dead organic matter.
When food runs out or when environmental conditions support it, the plasmodium begins to form fruit bodies (sporangia) that produce spores. These often beautiful fruitbodies range in size from around 50 microns (0.050 mm) to more than 70cm in diameter (Keller & Everhart 2010).
Slime mould spore containing fruiting bodies (sporangia)
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Plasmodium forms fruit bodies that release spores
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From spores emerge myxamoebae/swarm cells. The myxamoaebae that emerge from spores, can become dormant 'microcysts' when conditions are unfavourable, quickly resuming life when conditions are right.
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Myxamoebae/swarm cells divide and feed
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Compatible myxamoebae fuse to form a zygote.
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The zygote cell nucleus repeatedly divides by mitosis to form a feeding plasmodium. The plasmodium is a multinucleate (many nucleus), and the weblike form increases surface area available for nutrient uptake.
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Plasmodium forms fruitbodies (sporangia) when conditions change. These sporangia release spores.
FUN FACT!
Slime moulds can solve puzzles and control robots! They have even been to outer space!
Physarum polycephalum is a slime mould that has been observed displaying a type of primitive intelligence using cellular computation to solve mathematically difficult problems. In an experiment with nutrient agar placed at the start and end of a small labyrinth, the slime mould took shortest path to the food source, rather than spreading out into different paths."The mould seemed to swirl itself into one thick tube, thereby increasing its foraging efficiency as well as its chance of survival." (Gangadharan & Raman 2021)
Touchy- Feely! Slime moulds may explore through fields of attractants and repellents, perceiving through physical touch and chemo-receptors. Being able to sense higher concentrations of attractants helps the slime mould maximise how it grows and colonises a substrate eg: decaying wood (Adamatzky et al. 2013).
Slimes in Space!
Slime moulds have been used in experiments in American, German and Russian space programs (Keller & Everhart 2010) .
Bio-computing with Slime Moulds
Laboratory experiments, show slime mould Physarum polycephalum could possibly contribute to self-growing bio-electronic circuits!
(Gale, Adamatzky & Costello 2015)
Would you eat moon poo?
Indians from the area of Cofre de Perote in the state of Veracruz, Mexico, call Fuligo septica “caca de luna” or translated into English mean “excrement of the moon.”
The yellow plasmodium stage of Fuligo septica was reportedly eaten by the Cofre d Perote Indians, who fry the scrambled-egg-like stage with onions and peppers on a tortilla.
(Keller & Everhart 2010)
The Slime mould Fuligo septica - Is commonly called 'Dog vomit slime mould. In Mexico it is also known as caca de luna' or 'excrement of the moon'.
Collembola (springtails) often found on slime moulds.
How do the spores of slime moulds
spread in the environment?
The spores of slime moulds are mainly spread by environmental factors such as air currents, by the wind and through water. Tiny creatures also play a role in depositing spores, including mites, worms, flies, beetles, nematodes and slugs (Keller & Everhart). 2010) .
Larger animals including birds and lizards, may relocate spores as they come into contact with, or feed on, the slime moulds in their travels (Lloyd 2018).
Slime mould spores are usually round (globose), with either smooth, spiny, warty or reticular surfaces. This variation in spore surfaces may play an important role in the ability of the spore to travel through the air because of the water resistant properties (hydrophobic properties), it may give to the spores, making it easier to become airbone in rain/wet situations (Lloyd 2018).
Grow your own slime moulds!
1. Collect some bark, leaf litter, moss or dung. Even collecting cultivated orchard apples is worthwhile for viewing slime moulds!
2. Boil some tap water and let it cool.
3. Get clean, clear containers with lids. Plastic 'takeway' containers, glass or petri dishes work. Wet a piece of paper towel with the cooled water and place onto the bottom of the container.
3. Place your items in the container and if you have a water sprayer, mist the items well with your cooled water before closing the lid. Items should be moist and not overly wet. Any excess water sitting on the bottom should be drained off. Make a note of where each item came from. For example, 'wallaby dung', 'eucalyptus bark', and place it with the matching container.
4. Keep the containers inside, out of direct sun. Watch it over them, the next few days, as some slime moulds may appear quite quickly. Then check in once a week to see how it is going as others may take a while longer to appear. Checking it every few days to see it isn't drying out, and spraying if needed.
5. Look for emerging fruitbodies with a magnifying glass, hand lense or microscope and draw or photograph what you see! When they completely dry out, place each one in it's own cardboard box and place in freezer for a couple of days to kill any insects. Then store in cool, dry place.
The following website were sources for the above information and contain further information on growing slime moulds.
How to Create a Slime Mould Moist Chamber by Kelly Brenner
Armchair Foraying by Sarah Lloyd
The Bark myxomycetes - their collection, culture and identification by DW Mitchell
Metal Detectives
Similar to fungi, slime molds accumulate metals. For example, Fuligo septica contains billions of spores inside a thick calcium carbonate crust and has also been found to store metals including barium, cadmium, iron, manganese, and strontium.
Slime moulds beneficial to human medicine
Slime moulds Fuligo septica (Dog Vomit Slime Mould) and Lycogala epidendrum (Wolf's Milk) are two of many slime moulds that have been found to produce antibiotics. A number of other slime moulds also produce pigments and novel chemicals including ones cytotoxic to cancer cells and showing antibiotic activity (Keller & Everhart).
Lycogala epidendrum (Wolf's Milk)
References:
Andrew Adamatzky , Rachel Armstrong , Jeff Jones & Yukio-Pegio Gunji (2013) On creativity of slime mould, International Journal of General Systems, 42:5, 441-457, DOI: 10.1080/03081079.2013.776206
Burki, F. Roger, A.J., Brown, M.W. & Simpson, A.G.B. (2020) The New Tree of Eukaryotes, Trends in Ecology & Evolution, v.35, iss.1, pp. 43-55.https://doi.org/10.1016/j.tree.2019.08.008.
Campbell, N.A. & Reece, J.B. (2002) Biology, 6th ed., Benjamin Cummings, San Francisco.
Chinchilla Field Naturalists' Club (2007) Fungi out west: some fungi of southern inland Queensland, Cranbrook Press, Toowoomba.
Fuhrer, B. (2005) A field guide to Australian fungi, Bloomings Books, Melbourne.
Gale, E., Adamatzky, A. & de Lacy Costello, B. (2015) Slime Mould Memristors. BioNanoSci. vol.5, pp.1–8
https://doi-org.ezproxy.cqu.edu.au/10.1007/s12668-014-0156-3
Gangadharan, S. & Raman, K. (2021) The art of molecular computing: Whence and whither, DOI: 10.1002/bies.202100051.
Keller, H. & Everhart, S. (2010) Importance of Myxomycetes in Biological Research and Teaching, Papers in Plant Pathology 366, https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1366&context=plantpathpapers
Lloyd, S. (2021) Armchair Foraying, https://www.disjunctnaturalists.com/articles2/armchair-foraying.htm
Lloyd, S. (2018) Where the Slime Mould Creeps, 2nd ed., Tympanocryptis Press, Tasmania.
Lloyd, S. (2021). Tasmanian Myxomycetes, https://sarahlloydmyxos.wordpress.com
Mitchell, DW 1977 'The bark myxomycetes - their collection, culture and identification.' The Journal of the association for Science Education - The School Science Review Vol 58, No. 204. https://www.disjunctnaturalists.com/articles2/mitchell1977.pdf