3-Dimensional Path Finding

[Bob Lowe]

I'm curious, what is known about physarum's ability to find three dimensional paths? I ask because I have observed an interesting behavior in my slime cultures on two occasions over the last few weeks. 

I have been keeping my slimes in disposable food containers which have tapered sides and are approximately 4cm deep. Sometimes, when I change their bedding, the culture will explore the sides and the lid before moving on to the new paper. (I have been using construction/sugar paper as my primary substrate.) Usually, when it finds the oat flakes, it retreats from the sides to the paper and stays on the bottom so long as I keep feeding them.

However, on two occasions it did something differently. On these occasions, the culture began crawling up the side and across the underside of the lid in its fanned out in a tree search pattern. It also had a few fans moving across the paper. When it found the oats, which were near the center, rather than retreat down the sides, it actually expanded downward from the lid! Of course I have seen them drip down off the lids before (especially in response to light) but in these cases, it hit the center of the oat flake piles with expert precision. It was not like the other drips in that it was just one bridge and not several of them. After the bridge made contact, the slime pulled itself apart. The slime nearest the bottom crawled across the paper, the rest flowed down the vertical bridge to colonize the food.

Has anyone else noticed them doing this? I am working on an experiment to trigger this behavior so I can see if it was simply chance or if they really can find food with their lower half and then coordinate with the upper half to reach their food.