In recent decades, the blob called Physarum polycephalum has aroused the interest of scientists. Why? It has surprised scientists due to its surprising intelligence.
The blob is neither an animal, plant, or fungus. However, it has inhabited the Earth for almost a billion years. It is one of the oldest and simplest living beings on our planet.
The blob is a type of myxomycete (a group of amoeboids that form some 1,200 species known to date). It is a single-celled organism that contains many nuclei. It spreads across the ground, generating a series of tentacles or heads. It moves at an average speed of one centimeter per hour. When it is hungry it can move up to 4 centimeters per hour. This blob is composed of a single cell that doubles its volume daily and can measure several meters in diameter.
The blob can be found in humid, shady areas with cool temperatures. It usually feeds on decomposing organic matter. For instance, on leaves and tree trunks on which microbes, bacteria, and fungi have grown.
In its vegetative phase, the blob is a plasmodium. Its body is a protoplasm with several nuclei inside and moves on the ground and searches for food. When humidity or temperature conditions become adverse, the blob dehydrates and enters a dormant phase called “sclerotium.” For long periods, the tissue hardens, preserving many cell nuclei, and can remain in this state. When environmental conditions become appropriate again, the blob resumes its activity and continues its food search.
On the other hand, when there is a lack of food, the blob begins its reproductive phase. It has about 720 different sexes. Reproduction begins when the plasmodium forms stems that generate spores. These spores are released into open spaces to facilitate their spread with the wind.
The spores that have dispersed can be dormant for years. However, when they find favorable conditions for their growth, they germinate. They also release amoeboid cells that fuse to form a new plasmodium.
Why is the blob interesting for science?
The blob has several surprising qualities intriguing researchers despite its apparent simplicity.
Among other things, the blob has been studied to understand cell movement. The plasmodium moves while generating a flow of protoplasm. Each round trip of this flow takes approximately two minutes.
Even though it doesn’t have a nervous system, it is a learning single-celled organism. Scientists performed several experiments to expose the blob to bitter substances such as caffeine and quinine. After a few days, it was found that the blob ignored this harmless bitter substance. That is to say, he had become accustomed to it.
In other experiments, it was also seen that it was able to overcome mazes, avoid traps, and take routes that maximized the obtaining of nutrients. It established connections between various food sources and had different necessary nutrients for its subsistence.
It was also seen that it followed a trail of oats and rerouted the subway network of the Tokyo metropolitan area. This optimized the distances traveled, as the engineers who had built this network had previously done.
Although this amoeboid lacks a nervous system, it can solve complex problems and develop strategies to optimize its mobility.
It is also capable of generating an external memory. How so? The slime releases a type of mucus it has passed that is repulsive. However, it avoids areas where mucus is released when exploring (and has not found food).
Is the blob an intelligent organism?
Until the 20th century, the idea of intelligence had been reserved for human beings. Our species was considered the only one capable of solving complex problems and reflecting on our actions.
However, during the last century, scientists began to recognize the ability of other animals to solve problems, design strategies, remember long-term events, or make decisions. Scientists associate the use of “intelligence” when referring to complex living beings with a nervous system and brain. The study of the behavior of simple living beings is questioning this concept.
The idea that there can be intelligence in beings that lack brains is gaining more and more strength. To know if other simpler organisms are intelligent, it is first necessary to consider what is meant by “intelligence.” This term refers to problem-solving to maximize the chances of survival in the (often hostile) natural world, and all living things will be endowed with it.
The blob is the first single-celled living being in which the ability to learn through habituation has been found. But is it capable of transmitting or communicating this learning to another blob?
When one blob comes into contact with another, it can transmit its previous habituation. This is further proof of their capacity for intelligent behavior. Blobs use a communicating vessel to interact. Intracellular fluid is transferred through an injection of fluid or protoplasm and transmits the acquired knowledge.
Therefore, each blob can generate its knowledge based on experience. It transmits knowledge to the other blobs it encounters.
All these discoveries have made scientists globally consider the possibility that there is more advanced cognition than previously believed in all living beings.
Mitsch, J. (Director). (2020). Le Blob. Un génie sans Cerveau. [Motion Picture].