Physarum polycephalum, also known as the many headed slime mould, is a single celled Eukaryotic microorganism that grows in damp and dark places where it consumes other microbes, such as fungal spores and bacteria.

Here this yellow pigmented slime mould was given a choice of four naturally pigmented bacteria as its sole source of food, Serratia marcescens (red), Micrococcus luteus (yellow), Arthrobacter polychromogenes (blue) and Chromobacterium violaceum (purple.

The slime mould (centre) and the four naturally pigmented bacteria just after inoculation

After overnight incubation, it had moved towards and begun to assimilate the yellow and blue pigmented bacteria but seemed to be avoiding the red, and to a lesser extent the purple pigmented bacteria

The slime mould and bacteria after overnight incubation

The slime mould and bacteria after overnight incubation

The slime mould assimilating the yellow and blue pigmented bacteria but avoiding red

The slime mould assimilating the yellow and blue pigmented bacteria

After further incubation, the slime mould continues to assimilate the blue and yellow pigmented bacteria whilst avoiding red.

The slime mould avoiding the red pigmented bacterium

After further incubation, and having assimilated the yellow and blue pigmented bacteria, the slime mould now begins to feed on the purple pigmented bacterium having avoided it at first.

The slime mould assimilating the purple pigmented bacterium

Eventually it approaches the red pigmented bacterium

The slime mould feeding off the yellow, blue and purple pigmented bacteria and now approaching red

Eventually, the slime mould has consumed the yellow, blue and purple pigmented bacteria leaving some pigmented residue but still has not consumed red and sporulates rather than doing so.