The majority of the slime mold now only exists and connects along the shortest path from the beginning nutrient block to the end nutrient block. The third image in the top-right shows the slime mold decreasing in volume again after 4 hours. The second image on the bottom-left shows that the initial volume of the slime mold decreases after 4 hours and the majority of the slime mold exists and connects along every possible path from the beginning nutrient block to the end nutrient block. The first image in the top-left is taken after the slime mold completely saturates all parts of the maze, and before two nutrient blocks are added to the start and end point of the maze. There were four possible routes (α1, α2, β1, β2) between the start and endpoints" (Nakagaki, et al., 2000).Ī maze is created and filled with the slime mold Physarum polycephalum. At the start and end points of the maze, we placed 0.5- x 1- x 2-cm agar blocks containing nutrient (0.1 mg/g of ground oat flakes). The plasmodial pieces spread and coalesced to form a single organism that filled the maze, avoiding the dry surface of the plastic film. We then positioned these in a maze created by cutting a plastic film and placing it on an agar surface. "We took a growing tip of an appropriate size from a large plasmodium in a 25 X 35 cm culture trough and divided it into small pieces. The procedure, as described in the Nakagaki paper, is quoted below: Here we show that this simple organism has the ability to find the minimum-length solution between two points in a labyrinth" (Nakagaki, et al., 2000). It changes its shape as it crawls over a plain agar gel and, if food is placed at two different points, it will put out pseudopodia that connect the two food sources. "The plasmodium of the slime mould Physarum polycephalum is a large amoeba-like cell consisting of a dendritic network of tube-like structures ( pseudopodia). In a way, it "solved" the puzzle of finding the shortest path through the maze!Īccording to the abstract of the paper, here is how the authors sum up the findings: In all cases, the Physarum polycephalum chose the path that was the shortest between the two food sources. At the same time, if a food source is placed at the entrance and exit to the maze, they avoid dead ends in the maze and form a connection (as a single tube) between the food sources. If the Physarum polycephalum organism is chopped up and dropped into a labyrinth (a maze), they put themselves back together and start to move. You can watch the video below to get an idea of how this can work. Nagakaki and colleagues in Japan have shown that Physarum polycephalum can find the shortest distance through a maze. One of the most interesting things about Physarum polycephalum is that it shows a quality that could be called primitive intelligence. This is probably the least understood of the five kingdoms of life the others being animals, plants, fungi, and bacteria. Slime molds, like Physarum polycephalum are part of the kingdom Protoctista. It can be fed rolled oats as it grows, and divided to a fresh plate when it has grown to cover the first surface. Physarum polycephalum is inexpensive to obtain and it can be easily cultured on a moist surface, such as a damp piece of filter paper or an agar plate (agar plates are easier to use because they stay moist). The organism is sometimes shipped as a sclerotium when purchased from scientific supply companies. It goes into a kind of dry, dormant state, called sclerotium from which it can revive itself if it becomes moist. Germination of the spores leads to the formation of a new plasmodium.Ī curious variation occurs when the plasmodium encounters conditions that are too severe for it to continue growing, but not severe enough to cause it to form sporangia. The sporangia produce spores that can be spread by the wind to new regions for the organism to grow. If the conditions that the organism finds itself in become challenging-for example, the ground becomes dry or food becomes scarce-the plasmodium will begin to shrink and form sporangia. In this plasmodial stage, Physarum polycephalum is a bright yellow glistening mass that can grow to more than a foot across. It consumes bacteria and decaying organic matter. In its growing stage, Physarum polycephalum looks like a giant amoeba that spreads out like a fan, enveloping and eating everything in its path. Physarum polycephalum growing in Olympic State Park.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |