How Slime Moulds Remember Where They Ate

The slime mould Physarum polycephalum has no brain or nervous system — yet it somehow ‘remembers’ the location of food that it ate. Slime moulds are simple organisms made up of interlacing tubes — but previous research has shown they can solve complex problems, such as finding the shortest path through a maze. Scientists found that when parts of P. polycephalum come into contact with a food source, they release a substance that softens the gel-like walls of its tubes, making them widen. The slime mould moves by expanding along wider tubes and pruning narrower ones, so the enlarged tubes effectively record past food sites.