RSPB Trainee Ecologist, Chris Knowles, explains the difference between slime moulds and fungi.

When is a fungus not a fungus?

I’ve been having a fabulous autumn, everywhere I go the world is sprouting mushrooms... and looking for mushrooms is usually why I am outside. I like to think I’m pretty good at finding them too, so it is always a little disconcerting when I’m led astray by puzzling pretenders.

It took someone else to point out that I was barking up the wrong taxonomic tree with this one for example:


1. Trichia decipiens - seen here at home, next to a pencil, being threatened with a scalpel and beginning to release spores.

It's sometimes an easy mistake to make – the slime moulds pictured here were long thought be fungi, just as fungi were for a long time considered to be plants. It is now accepted that neither is even slightly true.

The slime moulds (myxomycetes) are fantastically baffling and intriguing in their own right though. They spend much of their lives as tiny single-celled, amoebae-like organisms; until their food supply starts running out. Then the individual cells signal to each other chemically and come to together, joining up to form a mighty new being... well a mighty new being that looks like goo anyway.

2.   Fuligo septica, is commonly known by the great name ‘Dog’s vomit slime mould’ or in Scandinavian folklore as Troll cat vomit. There is also a yellow variety known as ‘Scrambled egg slime mould.

This new structure (a plasmodium) is then able to move in a similar manner to a slug, and indeed the previously independent cells now organise themselves into being ‘head’ and ‘tail’ and secrete a slime on which to travel in search for a new food supply.

3.   Reticularia lycoperdon, (The false puffball) has changed from the mobile phase to the spore producing phase.

Not content at shifting from being amoeba-like to slug-like... to reproduce the slime mould cells will then take on their pre-set role of becoming stalk or spore producing cells to become fungi-like structures like those shown here.


4. The spore producing (sporangium) stage of two slime mould species.

Their uncanny nature has not been overlooked by science either, in 2010 a slime mould was let loose on a map where small piles of oats represented the main cities and towns of Japan. In less than two days the slime mould fanned out over the map, and then shrank back to a fine network that allowed it to pass the food supply most efficiently throughout the organism. The network was a good visual match for the existing Japanese rail system that took years of planning to design.

3.   Steminitis sp. releasing spores

In another experiment a slime mould was used to control a small robot. As the slime mould was light-phobic it would attempt to move away from light sources, this movement would then trigger the robot to move in the same direction.

So sometimes I do confuse these tricksy myxomycetes with fungi, but I’m sure I’ll get better at telling them apart. Especially as I’ve never seen a mushroom drive a robot train around Japan.