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What is slime mould (Physarum polycephalum)? © Getty Images

What is slime mould (Physarum polycephalum)?

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Argh… a yellow, wood-dwelling creature without a brain, capable of thinking and able to reach a metre in length as a single, supersized cell.

Deep in the woods lurks a creature with no mouth, eyes, or brain. An oozing, yellow mass that thrives in decaying leaves and logs. Let’s celebrate Physarum polycephalum – a species of slime mould that thinks without a mind.


In its early life, this creature exists as a single-celled organism. But when times get tough, it has a trick up its sleeve. Each P. polycephalum can merge with the individuals surrounding it, forming a super-sized cell that’s capable of reaching a metre in length that can slowly creep towards nearby food (usually fungal spores and bacteria).

Recently, P. polycephalum has become the lab rat of slime mould research. It’s able to escape from traps and find its way around mazes, and it’s been shown, when given a choice, to seek out the most nutritious food – porridge oats, apparently. A particularly memorable experiment involved P. polycephalum gradually learning to ‘ignore’ chemicals that had been placed to block its path to food. This behaviour suggests a primitive form of memory, and no one knows quite how it manages this feat.

Worldwide, there are thought to be around 900 slime mould species, yet many more are likely awaiting discovery. You may think them primitive, certainly, but you’d be wrong. What we achieve in a trillion cells, they manage with just one.

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