In many fungi, the DNA storage compartments called nuclei are not prisoners of the cells they reside in, the way they are in animals and plants. Instead, fungal nuclei are free to move about the cabin. They flow through the joined, tube-shaped cells of fungi like busy commuters, and experience many of the same dynamics. (Click "source" to view video)
Why might fungi do this? As you saw in the video, a fungus is a collection of pipe-like filaments called hyphae (HIGH-fee). In many, but not all, fungi, each hypha is divided into cells by walls called septa (You can see such a wall in the video from 1:26-1:36. Look in the center of the image. A pore permitting the nuclei to pass is invisible from our viewpoint). The hyphae often branch and rejoin to form a complex network, collectively called a mycelium (my-SEE-lee-um).
A fungus like this one is essentially one giant cell. This is because each septum is pierced by a giant hole that allows the cytoplasm — the goodies inside a cell — to flow freely within the mycelium. The flow of cytoplasm is important in fungi because they can only make new cells at the tips of hyphae — not in all directions as animal and plant cells do. These fungi need to be able to push cytoplasm to feed and fill that growing tip.
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