King of All I Survey-Chapter 221: Parasitic Sap?
I should say it almost reached the first one. When it reached a distance about a foot away from the first sap slug, following its exact path, it suddenly changed direction, angling to the left. It went around the other sap slug without touching it. Somehow, it had to 'know' it was there. Maybe there was some chemical residue slightly different in the first one's slime trail that it exuded when it got close to the wounded site? Or maybe the wound itself emitted a detectable chemical clue… but then the second one would have had to also detect that the first one had already covered the wound and more importantly, decide that meant it should go around rather than continue on. The implication was startling.
This slug-like creature that Rafael had named the Ceiba Sap Slug was a detached part of the great tree, yet it seemed to have some rudimentary ability to make decisions. No, I was reading too much into it. There was probably some simple reaction that caused it to go straight toward the scent of the sap, but another that caused avoidance of other sap slugs, simple chemical triggers. The second slug circled around the first one to head to the line of sap that had dripped down from the wound before it was covered. But that line ran all the way to the wound in the tree bark. The slug intercepted the line of sap at the same distance from the first one it had kept in its approach, about a foot away. Then, its front edge moved across the thick trail of sap. When its front edge passed over the sap onto clean bark again, the slug turned facing downward on the tree trunk, following the line of sap until its entire body was lined up with the sap flow. Then it stopped.
The view zoomed in again to show just the lower sap slug. At first there was a raised section caused by the thick layer of sap beneath it, but this began to smooth out as the entire body of the slug slowly filled. It was subtle at first. The sap was about a half inch thick so it was only with the close-up view that I saw it. After maybe ten seconds of this, the back end of the slug began stretching upward along the line of sap. Toward the first sap slug. It went right up to the edge, but never touched the first one, staying perhaps a millimeter away.
This left a very thin line of sap uncovered, a tiny amount. After another ten seconds or so to soak up or absorb the sap under it, the slug began moving downward following the trail of the sap. It moved a full body length, then paused in place to absorb the sap, growing thicker it did so. It continued this way until it had covered and absorbed all the sap that had leaked from the wounded tree trunk. When it finished it was no longer had the flat appearance of a see slug. Instead, it was now more like an ordinary land slug, with a thick rounded body. It started backing up following its previous trail again diverting around the previous sap slug as it following the precise path it had used on its way to the exposed sap. Along the edges of the pudgy slug, there was a flattening where it was apparently forming a moving seal against the tree bark as it used its two-part adhesion to remain attacked. It was much heavier now, and its surface area to weight ratio was much lower. It was clear now why it needed the mechanical suction cup action to keep its new weight from pulling it free of the bark.
It went completely around the previous slug again and followed its path to the top of the tree. It took some time. During its ascent, Rafael resumed his narration, "let me show you the first slug again. You may have noticed that the avoidance action of the first slug allowed a tiny line of exposed sap to remain untouched between the two slugs. If we look closely now, it's gone. The first slug has extended its thin outer membrane to cover it completely. Our observations have shown this border area of untouched sap measures between 0.8 and 1.1 millimeters every time we've measured so far. The first, wound-covering slug always extends its skin over it until it touches the bare tree bark. Once it does, it forms a tight seal, effectively merging with the bark."
"You'll see that the outer surface of the 'bandage slug' is changing now. It's thickening and getting less pliable. It's actually becoming tree bark. Within two hours, it varies by the size of the wound, it will look just like the rest of the tree bark in texture and color. As it transforms, it continues applying a physical pressure to the excess sap, forcing it through the cell membranes into the rest of the tree trunk. The amount of time it takes to becomes perfectly flat and level with the trunk depends upon how full of sap it was to begin with, but a few hours at most."
The view then shifted back to the other slug still climbing. "This one has now fresh wound to use to transfer the sap back to the tree and to reattach itself to the main organism. Instead, it will climb the entire trunk height and affix itself to the central vein of the frond. The reabsorption and sap transfer happens faster there, presumably because the frond's outer surface is softer and more readily accepts the inflow of pressurized sap from the attached slug. When that one finishes, its outer surface will match the color and texture of the frond. The green color of the frond does not carry through to the slugs when they separate themselves from the frond. However, the cells which eventually become part of the slug do have the green coloration until it begins the process of separation, and again after it has reattached. It seems to leave its chlorophyll-like components behind in the main frond as part of the detaching process."
"As far we can tell, the Ceiba sap slugs have absolutely nothing that we would call a nervous system, unless you consider the individual nuclei of the cells themselves. The sap slug is composed of exactly two types of cells. The outer 'skin' cell, which seems to be mutable in that it can rearrange its internal protein structure to become flexible and soft as we see in the slug, like a contracting muscle as we see when it is forcing the sap back into the tree, or more rigid and dense, with included chlorophyl-like additions and a cellulose-like polymer that gives it strength and rigidity. That's just one cell type. A cell that changes as needed.
"The other type of cell remains in one state all the time as far as we can determine. It is much smaller than the other cells and completely lacks any ability to change or move3 beyond basic replication which it performs by splitting. That small unchanging cell… is what comprises the sap itself." The view on the screen shifted again from the slug which had stopped moving after finding a place on the vein of the frond adjacent to the tree trunk, to a broader view of the trunks and spaces of the Ceiba tree forest covered by a canopy of its own fronds. Then, it swung around to show Rafael's face. 𝑓𝑟ℯ𝘦𝓌𝘦𝘣𝑛𝑜𝓋𝑒𝓁.𝑐ℴ𝓂
"The sap itself is a living part of the tree. It is not a separate nutritional substance or a liquid medium to carry nutrients throughout the tree. It is part of the tree. It does contain concentrated nutrients required by the other larger cells, and it does carry those nutrients to the bigger cells. The ceiba tree doesn't have a circulatory system of xylem and phloem like many earth plants. Instead the small nutrient dense sap cells move through and between the larger cells by either changing physical pressure or an osmosis-like migration triggered by varying concentrations of either the small cells within the larger cells or some other chemical triggers in the internal fluids of the larger cell. We still have some work to do to understand just how this works. When the sap leaks out of a wound, like the one I created on this trunk with my machete, it is because we have cut one or more of the larger cells and let its internal contents spill out. The sudden low pressure and changing chemical composition of the damaged larger cell causing an influx of the smaller cells which continue to leak out until the wound is 'healed'. Generally, the damaged cells don't die. If the cell was in the green frond form, its outer membrane will stretch to seal itself over the space of a few minutes, perhaps fifteen to thirty minutes. If the damaged cells are part of the tree trunk, they lack the flexibility for this and rely instead of the sap slugs to come and seal the wound and stop the outflow of sap cells. In both cases, the sap slugs collect any spilled sap cells and return them to the tree."
"Here, under the canopy, there are very few things that eat the sap. Outside, however, nearly everything eats the sap whenever it can, even if its primary diet generally consists of something else. Oddly, so far as we can determine, nothing we have seen actually attacks the Ceiba tree to cause the sap to leak out where it can be eaten. Nothing grazes on the fronds or bores into the trunks. Eating Ceiba sap is a purely opportunistic event dependent upon the tree being damaged by some random natural event. Or by human intervention, now that we are here."
The high-pitched voice coming from Rafael's familiar face was weird and went counter to the serious expression of his features. We haven't yet studied how other creatures break down and digest the sap cells which are still living when they are ingested. We don't know if they die when they are consumed by other creatures of it they can still move through the hosts creature's cells the way they do when they are inside the Ceiba tree. We don't think they can. The Ceiba tree's other cells are exceedingly large, a trait that we have not found in other life on Ri Ja so far, though we admittedly have only looked at a small subset in detail at this point. Either way, the use of Ceiba tree sap as food or even coming into direct physical contact with it, is forbidden by my direct order, as a possible pathogen or even a parasite."
"While the Ceiba trees seem to hold great promise as a means to passively and quickly terraform planets, or at least create terraformed biodomes, there is still much we must learn before we think about exporting this life form from Ri Ja. That's one reason we have withheld it from formal registration with the UEC," he concluded.
