Slime Mould

While practicing archery in the woods this year, I’ve spotted some funny-looking fungus-type things that I’ve since learned are slime moulds. I was aware of slime mould as a weird life form already, having read research into using them for solving mazes and analogue computing applications, but hadn’t seen any in real life until recently. In June I shared a photo on Twitter of a “weird orange fungus” that had caught my eye in the woods (it was almost glowing orange – the picture doesn’t capture its intensity). Replying to that tweet, C. Reider identified it as Wolf’s Milk slime mould (Lycogala epidendrum).

That same weekend, I also saw this thing, which I later identified as Fuligo septica, also known as Scrambled Egg or Dog’s Vomit slime mould. Like other species, it has a resistance to high levels of metals, but this one is unique in its resistance to zinc – a property related to its yellow pigment. In this photo you can see the trail of slime that evidences its movement.

On the tree of life, slime moulds are classified as Protists, which means they are neither animal, plant or fungi. There are three types of slime mould: plasmodial, cellular, and amoeboid.

Plasmodial slime moulds are the most likely to be seen. These include Physarum polycephalum (the yellow one that solves mazes) and Fuligo septica (pictured above). They begin life as individual cells that join to form a plasmodium – a single-celled but multi-nuclear blob. The photo below shows Fuligo septica at an earlier stage in its life-cycle, when the plasmodium has transformed to a spongy aethalium, but before it releases spores, when it hardens and darkens.

Cellular slime moulds spend most of their life as a single-celled organism, like amoeba. But if food gets scarce, they emit chemicals that allow them to find each other and they join together into a multi-celled organism that can sense and move towards food. Individuals also converge in order to reproduce, in which case the cells differentiate in function, forming stems with fruiting bodies that release spores, like mushrooms.

Amoeboid slime moulds share some characteristics with both the plasmodial and cellular groups and are more difficult to classify.

The Forestry Commission, which manages these woods, have marked up some trees with fluorescent spray paint, and it’s easy to mistake a slime mould for a patch of paint among the pine needles on the forest floor. For example, here’s a Physarum polycephalus, which I spotted for the first time a couple of weeks ago. Closer inspection reveals the veiny network of the plasmodium.

This bright orange slime mould is Leocarpus fragilis. Up close, you can see that it’s made of lots of small blobs, each attached with a thread. These are the fruiting bodies on stalks that will release spores.

Last weekend, I found two white slime moulds. The first looks like small blobs made of individual fruiting bodies, like white caviar. I haven’t yet been able to identify this species.

The other one is probably Ceratiomyxa fruticulosa. At a glance, from head height, it just looks like some normal white mould on a rotting log. But looking closer you can see that it’s made of small translucent star-shaped fruiting bodies, a bit like fingers made of jelly.

[Addendum, 18/09/2022] This weekend going round the archery course, there weren’t as many slime moulds or fungi because it’s been drier recently. But I saw the same patch of Physarum polycephalus slime mould that has now turned from yellow plasmodium to black fruiting bodies (the ‘many heads’ referred to in the name polycephalus):

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