Slime Molds Can Remember Things Without a Brain

A picture taken on October 16, 2019 at the Parc Zoologique de
Paris shows a Physarum Polycephalum better known as a “Blob.”STEPHANE
DE SAKUTIN | AFP | Getty Images
A picture taken on October 16, 2019 at the Parc Zoologique de Paris shows a Physarum Polycephalum better known as a “Blob.”STEPHANE DE SAKUTIN | AFP | Getty Images
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Slime Molds Can Remember Things Without a Brain

A picture taken on October 16, 2019 at the Parc Zoologique de
Paris shows a Physarum Polycephalum better known as a “Blob.”STEPHANE
DE SAKUTIN | AFP | Getty Images
A picture taken on October 16, 2019 at the Parc Zoologique de Paris shows a Physarum Polycephalum better known as a “Blob.”STEPHANE DE SAKUTIN | AFP | Getty Images

A recent German study found that the slime mold - known as Physarum polycephalum or The Blob - seems to remember where it previously found sources of food even without a brain or nervous system.

P. polycephalum is one of the most peculiar forms of life on earth. It is not plant, animal, nor fungus, but a species of slime mold which lives in dark forests and enjoys damp and cool environments.

The creature wanders over dead plants with a significant speed eating all fungi, bacteria, and decomposed materials it may find in its way.

Early in its life cycle, P. polycephalum exists as a single cell with a single nucleus, but later it merges with other cells to form a huge single cell that looks like a yellow pool of mud.

Similar to the invincible creatures featured in The Blob thriller, P. polycephalum can reassemble its parts even after being ripped in pieces.

In 2000, Japanese researcher Toshiyuki Nakagaki discovered that P. polycephalum was capable of solving a simple maze to reach a food source.

Biological physicists Mirna Kramar and Karen Alim of the Max Planck Institute in Germany have discovered that this brainless, neuronless creature uses the very architecture of its body to store memories about where it has previously found food.

The body of this creature is composed of a complicated network of connected tubes. During a study that will be published on March 9, in the PNAS journal, the biological physicists found that when P. polycephalum discovers a source of food, it releases a chemical that locally softens the tube wall at the site of the food.

This then triggers the tubes to dilate, becoming wider, to expedite flow within the slime mold to the site. When it found and eaten a nutritious meal, those thick tubes remain in place so that it can quickly return to the site if food were to reappear.

P. polycephalum can reabsorb parts of its body if it stretches out exploratory tubes into a region that is inhospitable, or contains nothing of interest.

"This is not utterly dissimilar to how the human brain works. In this case, synapses, which send information between neurons, strengthen when we learn and grow stronger the more we use them, but can grow weaker if we don't - vaguely similar to the slime mold's tubes, which will grow thicker at sites of interest, but will die off or be reabsorbed if their presence is no longer useful to the organism," said researcher Karen Alim in a report published on March 1, on the Science Alert website.



Acropolis Trims Hours Again Amid Greek Heatwave

A drone view of the empty Acropolis, after the authorities closed the site for the hottest part of the day, as a heatwave grips Athens, Greece, July 8,  2025. REUTERS/Stelios Misinas
A drone view of the empty Acropolis, after the authorities closed the site for the hottest part of the day, as a heatwave grips Athens, Greece, July 8, 2025. REUTERS/Stelios Misinas
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Acropolis Trims Hours Again Amid Greek Heatwave

A drone view of the empty Acropolis, after the authorities closed the site for the hottest part of the day, as a heatwave grips Athens, Greece, July 8,  2025. REUTERS/Stelios Misinas
A drone view of the empty Acropolis, after the authorities closed the site for the hottest part of the day, as a heatwave grips Athens, Greece, July 8, 2025. REUTERS/Stelios Misinas

The Acropolis in Athens will limit its operating hours for a second straight day because of heatwave conditions, the Greek culture ministry said Wednesday.

The ministry in a statement said the world-renowned site would be shut till 5:00 pm (1400 GMT) "for the safety of workers and visitors, owing to high temperatures."

The four-day heatwave confirmed by meteorologists began Sunday and is the second to grip Greece since late June.

Temperatures are expected to reach 41 Celsius (105.8 Fahrenheit) on Wednesday, with a maximum of 37 Celsius in Athens, according to national weather service EMY.

The Greek civil protection authority has warned of high fire risk in the greater Athens area, in central Greece and the Peloponnese peninsula on Wednesday.

The heatwave will abate on Thursday.