Ceratiomyxa fruticulosa (Coral or white-fingered slime mold)
Slime molds are not fungi, but often look like fungi and for a long time we included them among the fungi. They were included in surveys of the Forest Biodiversity plots at Brooksdale. Species illustrated here were found during surveys of the plots or during walks nearby.
Slime molds recycle Earth’s nutrients by feasting on bacteria, yeasts and other small fungi in or on dead vegetation. They are found in soil, lawns, mulch and the forest floor, often on logs of deciduous trees. They are likely on leaf mold in your gutters or even an air conditioner, especially if the drain is plugged. They play a lesser role in recycling than do fungi, simply because there are far fewer species of slime molds and they cannot degrade all things organic.
Being a slime mold
Slime molds thwart taxonomy. They spend much time out of our sight, are likely the most adept shape changers on the planet and show intelligence. We have now moved them from Kingdom Fungus to Kingdom Protista – a wonderfully diverse kingdom that includes single-celled animals and single-celled algae. Slime molds confound things by being single-celled only part of the time.
When a slime mold spore germinates, it cracks, releasing an amoeba-like cell called a myxamoeba. They are abundant but we don’t see them. Most are smaller than this period. The myxamoeba usually move like an amoeba and engulf food like an amoeba, but they are not the amoebae you met in high school biology; they’re far trickier. When free water is available, they can develop flagella and swim about. When things are good, the haploid myxamoeba divides as it eats and appears willfully carefree about what it does next. When food runs out, one group of species releases signal molecules by which they find each other and create swarms of up to 1,000,000. From this emerges a tiny (2-4 mm), slug-like, multicellular organism called a grex. It has coordinated movement, crawls to a favourable spot and grows into a fruiting body. Near magically, the individual myxamoebae have combined and changed form and function to create a multicellular organism. This isn’t the way we expect either animals or plants to work. Chances of seeing the gelatinous mass of a grex are also small. Another group of species is more ambitious.
Developing plasmodium (left); Identifiable plasmodium (right)
These acquire forms we can see without a microscope, but they are equally magical. In this group, when food is short and the ‘let’s gather’ signal goes out, myxamoebae converge and produce a wholly different organism. They become a slimy, jelly-like plasmodium, much bigger, but without cell walls, although parts of the organism may have different functions. Soon it grows to something you can see, provided you bend well over, but still often unidentifiable (left photo). A little older, it has changed colour and we have identifiable fruiting bodies of Trichia decipiens on a birch log (right photo). Repeat visits may be necessary to identify a slime mold, but you get to witness a remarkable performance of shape-shifting. Some plasmodia are more easily identifiable.
Slime mold’s magic doesn’t end with shape-shifting. In the aggregated phase, they can solve mazes or seem to reason things out. Better yet, they can remember where the food is. Chop up a plasmodium that has learned the maze and each individual piece somehow remembers the maze. This has folks designing computers much intrigued, because it is parallel processing at its finest, although a tad slow. Moreover, the pieces can also reassemble themselves. Try that with your computer. Researchers have built a six-legged robot whose movement was remotely controlled by a Physarum slime mold. The mold directed the robot into a dark corner most similar to its natural habitat. Other slime molds are studied in some advanced mathematics courses because they appear to solve partial differential equations when they aggregate.
Despite being no more than a bag of amoebae encased in a thin slime sheath, slime molds manage behaviours equal to those of animals with muscles, nerves and ganglia or simple brains. Next time you see a slime mold, pause and see if you can discern what it’s thinking about. You have to be patient, but isn’t nature grand? Three other slime molds found at Brooksdale are illustrated below.
Some slime molds at Brooksdale
Fuliga septica (Dog’s vomit or scrambled egg slime mold)
(left photo credit: Jesse Wildeman)
Dog’s vomit is typically seen as a white to bright yellow, spongy layer of near any shape. The one on the left was moving left to right. There are remnants of its slime trail. You have to be very patient to see it move. It has now formed a rugose spore bearing surface. The one on the right has settled down and is producing soot-coloured spores. It is still a single celled organism – no cell walls but lots of nuclei (the spores do have cell walls). Dog’s vomit is the largest single-celled organism on the planet. The largest recorded was about 1 m across and quite hefty. Perhaps because it was found in Texas, it stimulated concerns of an alien invasion.
In Scandinavian folklore, Fuligo septica was considered as the vomit of troll cats; we have no troll cats in North America, so went with dog’s vomit. Fuligo is Latin for ‘soot’; the species name is from septicus, Latin for ‘putrid’ (as in septic tank). The intent is to convey the putrescence of bacterial decomposition. Bacteria are a big part of its groceries.
Ceratiomyxa fruticulosa (Coral or white-fingered slime mold)
Coral or white-fingered slime mold clearly reveals how slime molds morph in shape as well as colour. The plasmodium is the first indication that it is around. But then it needs to think some. Because there is a decision to be made.
The plasmodium of this slime mold is not always identifiable. Once it has decided what form to take, identification is easy. We don’t know what goes into that decision, but it provides a helpful excuse for another walk to see what form will emerge. The name likely derives from cerato, Latin for horny and myxa, Greek for lamp wick, but originally mucus, based on the notion of a wick dangling from a oil lamp spout, like mucus from a nose. Fruticulosa means abundance of fruit – each little finger is a fruiting body. Etymology can be entertaining as well as informative. Any ‘fuzziness’ on the fingers is the spores. Spores are produced on the outside surfaces. In members of this family, the plasmodium breaks up into individual cells before forming sporangia.
Lycogala epidendrum (Wolf’s milk)
Wolf’s milk changes colour as it ages. At the red or pink stage, the flesh is a pinkish, paste-like substance (like toothpaste, but not worth trying). By the grey stage, a wee squeeze produces a puff of greyish spores, like a puffball. The scientific name translates as wolf’s milk growing on a tree. The latter is true if logs also are considered trees. The wolf’s milk part merely mysterious, but memorable.
None of these are tasty or edible. Wolf’s milk is dangerous to some.
The complete report Slime molds and fungal species in and near Brooksdale forest plots is being updated and will be available.
Check out our related blog posts:
A fungus walks into a singles bar
Fungi – the ‘good’ and the ‘bad’
Left to right: Fred Bunnell (lead on text); Corey Bunnell & 3 Hydrocybe conica
