Fair point there. There are several different versions of the suggestion there: non-cell parts, cells that fill up the space they’re in with non-cell stuff or “background” cells that have a filled space above them. All three of them could be used to implement something like “mesohyl”, which is the skeleton/internal transportation system of sponges or indeed the fluid-filled body cavity of other animals.
These exactly could have the attributes you mention:
And you didn’t list “Circulatory” Complex as an advancement requirement yourself, which I think makes sense, because simple macroscopic plants/macro-algae and fungi don’t have this kind if thing I believe, instead they’re just thin. (Though complex plants definitely do have cavities!)
So cavities/transport system would be more something for if you want any thickness to your design and/or provide those bonuses.
As progression requirements what you did mention makes more sense:
And perhaps reaching 20 cells could require either a spindly shape, or require cavities to not suffocate yourself? (so a surface area for cells mechanic).
An addition we could have here: Nerve system (or primitive equivalent) if you want to be motile in Macroscopic, otherwise your large body is too uncoordinated to really move.
I would still want to have “muscle” as the thing that actually makes you move, while the “nerve” cells boost things. But for those muscle cells, we can have actomyosin fibres that are not organised into myofibrils. This is what you see in smooth muscle tissue (as opposed to skeletal muscle) and simple animals. That would require a new model though.
March 26th:
Since we’re trying to figure out a roadmap for our Multicellular stage designs, I figured I should write up a first design proposal on how our “muscle cellpart” would actually work. First things to note:
- We can’t have flexible multicellular organisms, so we can’t really show organisms moving as they would. But we can give the cell parts mechanical effects that would be produced as if they could flex the organism, in movement, turning, etc. (I am also guessing we cannot make the cells themselves flex, but at least the cell parts themselves should be able to be animated?)
- Some of the attributes I suggest depend on other changes to the Stage’s mechanics that may or may not happen.
- I have tried to keep required complexity to a minimum, because Thrive can be difficult enough for people to understand already.
- In real life for example a worm has both length-wise and lateral muscles to move. I have abstracted that out here, because of the low number of cells and the previous point. But also, that isn’t always the case, for example in C.elegans, which I based a lot of this mechanic on, moving via only longitudinal muscles.
Having said that, here it is:
Cell part - Actomyosin
- model: a smaller/thinner/slimmer version of a myofibril. (But potentially multiple in a cross/rounded shape instead of a line).
- Requires normal or double membranes. (Perhaps also possible in cellulose/chitin, but at reduced effectiveness)
- On the simplest level: boosts both movement speed and turning speed. If not trying to make placement complicated, that’s it. But if we want to add more complexity:
- Lining up more of them in the direction of movement adds more speed (beyond just adjacency)
- Movement speed is also boosted by any adjacent cells (not just other muscle cells), because those are also “pulled along”.
- Having them off-center from the origin is required to increase turning speed in that same direction.
- If we make Flagella and Cilia only function when on the “outside” of the organism, the muscle cells do not have that restriction.
- Instead of a constant force like flagella, there is an “oscillating” force application, to mimic swimming.
- There could be some delay in muscle activation that is counteracted if you have nerve cells. IN any case, I am still thinking of a way for nerve cells to combo with muscles very well.
The objective here is to balance things so that muscles are the logical way to move large Multicellular Stage organisms, and flagella are less effective.
Bonus:
While animal muscles use contractile elements in cells to make the cells contract (and pull on things the cell is connected to), the rigidity of cell walls makes this not as feasible in plants. But plants do have an alternative solution: hydraulics.
Precisely because plants do have that semi-rigid but somewhat elastic cell wall, it allows plants to use turgor pressure: the osmotic value inside the cell draws water in, but this runs up against the compressive force of the cell wall, making the whole rigid and strong. This is how herbaceous plants can stand up at all, and why they flop down when low on water.
But beyond that as seen in some species for leaf movement of various types, and of course some carnivorous plants, this effect can be used for pressure: by increasing the osmotic pressure, plant cells can press harder on their cell walls, pushing outwards (contrasting with muscle pulling). From what I can tell, the max strength you could reach with this isn’t necessarily weaker than with muscles, just slower and less precise. The big benefit is that while changing pressure costs energy, keeping the pressure on does not which is quite unlike muscles!
Now of course IRL plants and fungi don’t make as extensive use of this as animals do with muscles, but that doesn’t mean Thrive with cell walls can’t! Which is why I think it would be nice to also have:
Cell part - Hydraulic Vacuole
This is pretty much the “plant” counterpart to the actomyosin part.
- Model: like a vacuole, but more stretched out in a vertical direction.
- Requires Chitin or Cellulose membrane.
- Functions largely like actomyosin, but with key differences:
- The given speeds per organelle are lower.
- ATP consumption is much lower.
- Time between movement pulses is much longer.
- Delays are longer.
- Any position-relative effects that actomyosin has are mirrored. For example, you need hydraulic cells on the left to push you to the right instead of muscle cells on the right to pull you to the right.
The intention here is to:
- Put realistic constraints on the type of cells muscles work in in real life while still allowing good motility in 4/6 membrane types.
- Make cell-wall having species and wall-less species significantly different in the long-run, even in Macroscopic and beyond. For example, macroscopic motile creatures with cell walls would be like fantasy walking plants: slow, but powerful and tireless.