Question

1. Describe the characteristics of the slime mold Physarum polycephalum and how it searches for food ( Bonus). What Supergroup is it in?

Answer 1

The characteristics of slime mold Physarum polycephalum are given as follows,

1. cytoplasmic streaming - changes direction typically in 100 seconds because the cytoplasm undergoes a shuttle flow rhythmically flowing back and forth with speeds of up to 1mm/s.

Cytoplasmic flows enable long-ranged transport and dispersion of molecules within the cytoplasm

2. Under starvation the organism reorganizes its network morphology and thereby enhance its dispersion capabilities

3. Develops a richly branched network structure, also called “plasmodium”, to explore the environment for food.

4. It is a gigantic single biological cell with countless cell nuclei. The mega-cell has the unique ability to move its content through the entire cellular network.

5. Individual tubes of the network can periodically change their diameter and thereby pump the cellular plasma rhythmically back and forth through the network.

6. The network architecture is highly dynamic with flexible rearrangement of its junctions so When Physarum takes up nutrient by its surface, the plasmodium will grow but still maintains coherence of the network structure.

7.When conditions become increasingly dry, the plasmodium creeps to the surface of the substrate and ultimately forms characteristic fruiting structures, that resemble magically formed gems of nature. In form of the spores, Physarum survives and propagates until the whole life cycle restarts again after spore germination.

8. It has a sophisticated life cycle with several distinct stages including amoebal, flagellated, and plasmodial cells. and therefore used as a  model organisms.

How slime mold Physarum polycephalum serches for food :-

Physarum polycephalum is an amoeboid organism that forages for foood by forming the tubule network.

creates the extensive and highly efficient networks between food sources, it spreads and grows in search of food, and naturally organizes itself into a network of tube-like structures that quickly and efficiently connect its disparate food sources.

It maximizes its ability to find food by ‘remembering’ and strengthening the portions of its cytoplasm that connect to active food sources.  By rhythmically contracting and expanding its body, Physarum is able to move and grow its body in search of food.

When it fails to find the food or the food source dries up, it retracts its cytoplasm, and leaves behind a trail of slime which marks, which pathways are useful and which are dead-ends depending whether the food source is available or not. By trimming back connections and maintaining only active pathways, Physarum uses the least amount of resources and energy possible and still creates a resilient and fault-tolerant system.

Links between food sources are made in such a way that it covers the shortest possible distances and disruption in one area does not impact the overall health or efficiency of the slime mold’s network.​

Supergroup of slime mold Physarum polycephalum :-

Amorphea