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Physarum polycephalum

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The blob in a forest in Germanie

Physarum polycephalum is a species of myxomycete belonging to the family Physaraceae and the reign of Amoebozoa (as the amoeba). This curious organism is composed of a single giant cell. Although devoid of brain or nervous system, this living organism is still able to learn. It is not an animal, a plant, nor a mushroom. He has lived in the undergrowth for over a billion years. In its natural state, it feeds on bacteria and molds (fungi). In the laboratory, the scientists give them oat flakes.

Reproduction and life cycle[edit | edit source]

Reproduction[edit | edit source]

Blob (Physarum polycephalum), like us, comes from the fusion of two sex cells. They are not called ovule s or spermatozoa because the blob has 720 different sexes. Once in a moist mid-life environment, these sexual cells (called spore as for the fungi) go in search of a cell of the opposite sex. With over 720 possibilities, the task is rather easy. When two cells of the opposite sex meet, they merge to become a single cell. But there, unlike us, the cell will not divide, only its core will do it. The blob will grow according to the divisions of its nuclei until reaching record sizes.

Life cycle[edit | edit source]

Sporocysts of the Physarum polycephalum.

The main phase of the blob is plasmodium. This plasmodium consists of networks of veins that distribute nutrients, and many nuclei. It is during this stage that the organism looks for food. The blob surrounds its food and secretes enzymes to digest it. This process is called phagocytosis.

If the environmental conditions cause dehydration blob during feeding or migration, then a sclerot will form. The sclerotium is made up of very strong tissues serving as a dormant stage, thus ensuring the protection of the blob for many years. Once the favorable conditions returned, the blob reappears to continue its search for food.

When the food reserves are exhausted, the blob enters the breeding phase. Spore containing pockets [(sporocysts)] are formed in the plasmodium. These pockets are usually formed in the open air so that the spores are dispersed by the wind. Spores can remain viable for years. When environmental conditions are favorable for growth, the spores germinate and release flagellated cells. The cells then fuse to form a new plasmode.

The blob in its environment[edit | edit source]

Blob's Pseudopods
To move, the blob uses excrescences called pseudopods.The movement of the blob is related to the movement of its cytoplasm called cytoplasmic current . This movement is characterized by a change of direction from front to back of the cytoplasmic flow, with a time interval of about two minutes. Within the blob, the driving force is generated by the Muscle contraction followed by the relaxation of [[membranous] membrane] probably composed of an actin protein. The layer of filaments creates a pressure through which the cytoplasm flows inside the blob. The blob, unlike living beings able to learn does not use an internal memory like the man for example but an external memory. He uses for this his mucus that he leaves wherever he goes. As a result, each time he comes in contact with his mucus, he will know that he has already passed and will not come back. The blob has no eyes and therefore do not see its congeners but thanks to the mucus or rather the molecules chemicals present in its mucus, a blob can detect the presence of another blob. The largest blob observed in the laboratory was 10 m² (square meter). The largest observed in the wild measured him 13 hectare s.
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