The answer to our “Freaky Friday Fungal Quiz”: slime mold. And I should not have used “fungal” in the title. Slime molds are no longer classified as fungi. But I’ll stick with “freaky.” According to UC Berkeley, slime molds fall into three categories,
Plasmodial slime molds, like Physarum . . ., are basically enormous single cells with thousands of nuclei. They are formed when individual flagellated cells swarm together and fuse. The result is one large bag of cytoplasm with many diploid nuclei. These “giant cells” have been extremely useful in studies of cytoplasmic streaming (the movement of cell contents) because it is possible to see this happening even under relatively low magnification. In addition, the large size of the slime mold “cell” makes them easier to manipulate than most cells.
A second group, the cellular slime molds, spend most of their lives as separate single-celled amoeboid protists, but upon the release of a chemical signal, the individual cells aggregate into a great swarm. Cellular slime molds are thus of great interest to cell and developmental biologists, because they provide a comparatively simple and easily manipulated system for understanding how cells interact to generate a multicellular organism. There are two groups of cellular slime molds, the Dictyostelida and the Acrasida, which may not be closely related to each other.