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Mr. Mask
2014-05-04, 01:53 PM
Wondering about underground ecosystems. Without the sun, with no air or stale air, no rain, and with soil that lacks much nutrients, it seems hard to get an ecosystem going deep underground.


Have any ideas for how an underground ecosystem could work? An underground source of energy would be useful, and would probably be necessary. You could go with a system like that one dungeon game for the PSP, where slimes were able to multiply energy/nutrients and redisperse it into the soil (which defies physics).

jaydubs
2014-05-04, 02:27 PM
If you're going to design an ecosystem, start with a source of energy and think about how it flows. For most, that's the sun. Underground, you're probably looking at chemical, thermal, or something entirely magical.

Some real world examples you might want to think about include giant tube worms (http://en.wikipedia.org/wiki/Giant_tube_worm#Energy_and_nutrient_source). Or if you want something underground, try snottites (http://en.wikipedia.org/wiki/Snottite). Invertebrates and slimes that eat rocks could form the backbone of an underground ecosystem, with not too much of a stretch of the imagination.

You could alternatively have it based on some creature that can convert heat into nutrients. Once you get deep enough, heat is plentiful. Plants that use lava or vents of some kind instead of the sun. A little bit of fluff about their origins from the plane of fire, and you're all set.

Or, you could just make it something magical. Ley lines, spirits, something along those lines. If you'd like some inspiration, Mushishi (http://en.wikipedia.org/wiki/Mushishi) has some very interesting supernatural creatures that are explained more as organisms in a not-quite visible ecosystem.

VoxRationis
2014-05-04, 02:39 PM
I second the tube worm explanation. If you have an area which was previously highly volcanic (creating a network of lava tubes which now form the core of the ecosystem, with more stereotypical limestone caves only on the peripheries) but is now much lower-level in activity, you can have geothermal vents in certain areas—the natives might call them Deep Wells. Chemosynthetic creatures live in those wells and form the basis of those ecosystems featuring almost entirely carnivorous creatures (since tube worms are meat rather than plants).

Knaight
2014-05-04, 02:41 PM
Have any ideas for how an underground ecosystem could work? An underground source of energy would be useful, and would probably be necessary. You could go with a system like that one dungeon game for the PSP, where slimes were able to multiply energy/nutrients and redisperse it into the soil (which defies physics).

I'd be inclined to look at deep ocean ecosystems - it's not like there's a great deal of sunlight there, let alone things like nutritious soil. The key thing there for a lot of them is hydrothermal vents, which are often hot spots of biological activity (http://en.wikipedia.org/wiki/Hydrothermal_vent#Biological_communities). As such, underground hot springs could work for the center of underground ecosystems.

Basically, you've got the underground hot springs, which foster various extremophiles, including several that produce oxygen from CO2, preventing the air from getting stale. These basically end up as thick mats, as they do near hydrothermal vents, which are then grazed on by pretty tiny herbivores - think insects here, or other things about the size of insects. A larger class of carnivores then eats those, and it goes up from there.

Dungeon monster types can then be inserted in here. Some slimes could be mobile versions of the bacteria mats, with very high heat tolerances, which gather around hot springs, and possibly move from hot spring to hot spring, using up lots of the nutrients, which are then brought back up from deeper underground. These slimes would be relatively harmless, but also serve as food for slimes which aren't, and which process them by moving onto them, and using them up as food for their own gigantic communities of tiny connected organisms. There could even be a symbiosis here - the slime walls which hold them together are a different organism than the slime interiors, which eat some of the larger byproducts produced by the interior organisms.

The non-carnivorous slimes could also serve as food for various other mega fauna. As they are likely pretty harmless most of the time (though plant style defenses are very possible), these mega fauna would be roughly analogous to herbivores, with the things that prey upon them being more dangerous carnivorous species, making up the non-slime component of dangerous monsters.

ellindsey
2014-05-04, 04:32 PM
I just assume a radically different set of laws of physics based on the four elements plus light and darkness. I figure if I'm going to treat the game rules as laws of physics, I might as well go all out with it.

Surface plants absorb light from the sun, extract essence of fire from the air, and use it to bind water and earth into their tissues. Without any of those sources of nutrients, they die. Animals eat plant or animal matter, and then need to excrete essence of fire into the air, as well as eliminate excess water and earth. If you seal an animal in a closed chamber, the air will become saturated with essence of fire and the animal will suffocate.

Underground plants operate the same way, but instead of absorbing light, they absorb darkness. What do you mean darkness isn't a source of energy? Of course it is. There's both a positive and negative elemental plane, after all. As a result of absorbing darkness, underground plants glow, just as surface plants create shade. Animals may eat and subsist off darkness-based plants just as they would light-based ones. In the short term this has no side effects, but in the long term it may have been responsible for the development of the stranger races and creatures of the underworld.

There may elsewhere be 'plants' which subsist off the elemental forces of heat or cold instead of light or dark as well. Brown mold would be one example.

Eldan
2014-05-05, 02:36 AM
I really like Ellindsey's explanation, myself. I go four-element-Aristotelian/illumination science myself whenever I can. Dephlogisticated Air is a wonderful thing.

That said, I could see two things, other than the previously mentioned hydrothermal vents and chemolithotrophes:

-Sediment. It's a thing in a lot of real world caves, where you have entire ecosystems based around rainwater and the nutrients it brings in. Mostly leads to tiny arthropods and bacteria. Not very diverse.

-Radiotrophic fungi. There are fungi that can photosynthesize gamma rays. Build a fantasy version of that: there are areas of the underdark with sickness-causing magical fallout, but there are also giant fungi which live on it. Maybe one could build save havens inside the fungi, where one would be protected from the fallout. Could make for interesting villages full of sheltered sentients who hide there from all the large underdark predators who won't come there.

Rhynn
2014-05-05, 06:37 AM
I was gonna post about thermal vents and radiothropic fungi (http://en.wikipedia.org/wiki/Radiotrophic_fungus), but they've already been covered.

Expanding on the fungi: in a fantasy setting, you can have all kinds of radiation, and you can have plants, fungi, algae, mosses, etc. that convert these odd (or not odd) types of radiation into energy.

Hytheter
2014-05-05, 06:51 AM
Depending on your setting you could easily have your ecosystem depend on a backbone of bacteria/creatures/whatever that derive their sustencance directly from innate magic. Ellindsey's suggestion is similar in a way, and is itself an interesting concept.
Other than that I think the more "realistic" options options have been covered; chemosynthetic bacteria in hydrothermic vents or similar, radiotrophic fungi... not sure what else there is, but I wouldn't doubt the imagination of others.

Mr. Mask
2014-05-05, 07:35 AM
This sounds incredibly interesting. To sum it up.

Heat: It's possible to have creatures which convert heat into energy/nutrition? This would make areas like hotsprings, places with volcanic activity, and other heat sources a source of energy (the latter may have some trouble with earthquakes).

Rock/earth: Slime could conceivably convert rock/earth into energy. Snotites seem to need moisture as well, but that's probably not too hard to arrange.

Radiation: Some mushrooms can convert radiation into energy. This does require a source of radiation. I can't remember the specifics of uranium deposits, but they might be a good fit.

Spread: Some creatures could spread the energy, theoretically. It was mentioned that an eco system could run, with creatures making the oxygen and so forth.

Slime-eaten caverns. If you did have a lot of rock-eating slime, it makes me wonder if you could get caverns made by it after a few thousand years.

Eldan
2014-05-05, 07:59 AM
[QUOTE] Heat: It's possible to have creatures which convert heat into energy/nutrition? This would make areas like hotsprings, places with volcanic activity, and other heat sources a source of energy (the latter may have some trouble with earthquakes).[/QUOTE

Not so much, really. From what I understand, the creatures around hydrothermal vents are more interested in the energetically rich chemicals they spew out. There's entire complicated metabolic chains based on things like iron, sulphur and hydrogen instead of the carbon and oxygen more commonly used at the surface.

THat's not to say that you can't have creatures that use heat, of course.

Eldariel
2014-05-05, 08:01 AM
I'll say this - real life ants cultivate fungus in their hives for nutrition (hence why they bring leaves in, to serve as spawnbeds). Prototypically the Drow do much the same in D&D, though with further magical aid. That shouldn't be hard to extrapolate. Fungus can grow almost anywhere and even animals cultivate it.

Mr. Mask
2014-05-05, 09:35 AM
Eldariel: Well, it's not just a matter of whether civilized creatures can survive deep underground. Humans can do that now, magic could replace technology for achieving that. The thing is, why live deep underground? The main reason would be defence against nukes. Other than that, the only reason to dig deep is if you're looking for minerals--and the only ones who need to live deep are the miners (though living in a mine tends to be unpleasant and unhealthy).

Predators, ants, moles, worms, they shack up close to the surface, so they can get access to things like leaves which have energy from rainwater, sunlight and air. If you want creatures who are living deep underground, you need something there they want. Otherwise, they'll just living in shallow caves near the surface.


Eldan: I'm not sure of a scifi way of converting heat into nutritional energy. If there's something plausible enough, I'd be interested in using it for a setting.

Either way, heat sources can be sources of life if creatures can use them to get useful chemicals.


Chemicals: This makes me wonder if you could theoretically have deposits with particularly useful chemicals and minerals for sustaining underground life. The more possible sources of energy the better (underground living will probably end up frugal regardless).

VoxRationis
2014-05-05, 10:30 AM
I'll say this - real life ants cultivate fungus in their hives for nutrition (hence why they bring leaves in, to serve as spawnbeds). Prototypically the Drow do much the same in D&D, though with further magical aid. That shouldn't be hard to extrapolate. Fungus can grow almost anywhere and even animals cultivate it.

Yes, but they're still highly dependent on the outside world for an energy source. Those leaves they bring in fix the Sun's energy, and that energy, by means of the fungus, feeds the ants. I think what we're looking for here is for a subterranean ecosystem, isolated from the surface, to be self-supporting.

Eldariel
2014-05-05, 12:44 PM
Eldariel: Well, it's not just a matter of whether civilized creatures can survive deep underground. Humans can do that now, magic could replace technology for achieving that. The thing is, why live deep underground? The main reason would be defence against nukes. Other than that, the only reason to dig deep is if you're looking for minerals--and the only ones who need to live deep are the miners (though living in a mine tends to be unpleasant and unhealthy).

Predators, ants, moles, worms, they shack up close to the surface, so they can get access to things like leaves which have energy from rainwater, sunlight and air. If you want creatures who are living deep underground, you need something there they want. Otherwise, they'll just living in shallow caves near the surface.

I mean, for sentient life it can just be a question of space to move underground; there amount of space a subterranean race can inhabit is massive compared to a surface-dwelling one. If it wasn't so inefficient for humanity to use deep caves I bet we would already. We already dig tunnels under cities even though it's expensive as all get-out just to save space where it's considered most valuable. Imagine we were more closely related to burrowing mammals: I bet we would also use technology to dig and live a tad deeper than our genetic endowment would enable us to, perhaps generating just this sort of a subterranean world. Of course, as it stands we're quite reliant not only on sun as an energy source but also on direct exposure to sunlight to catalyze various things in our bodies so being so deep down is inconvenient and our psyche is not well-adjusted. But that's not really anything more than a trait that's in no ways set in stone; if we're to envision an underground culture, adjusting those is a small matter that wouldn't stretch things much.

Then again, even such a race would probably only go few hundred meters deep at best. If we're talking about an independent ecosystem kilometers deep, that's a different matter. Though, if we want examples of things that live without (direct) benefit of sunlight, deep-sea ecosystems are of course an easy target to observe; sunlight doesn't reach the ocean depths or anywhere near there. The only real source of light are the bioluminescent creatures, but water of course contains oxygen which is constantly replenished so living there isn't that difficult at a base-level (aside from the pressure).


Yes, but they're still highly dependent on the outside world for an energy source. Those leaves they bring in fix the Sun's energy, and that energy, by means of the fungus, feeds the ants. I think what we're looking for here is for a subterranean ecosystem, isolated from the surface, to be self-supporting.

Which brings it back to things like heat, lithovores, radiation and in general, minerals; fair enough.

Mr. Mask
2014-05-05, 01:14 PM
Subterranean living is actually quite suitable for humans. But, as you point out, there isn't a reason to go deep underground (other than, as mentioned, fear of nuclear war).


By the way, I started a thread asking about the possibility of creatures which convert heat to energy. NichG had a pretty interesting answer, and the others did too: http://www.giantitp.com/forums/showthread.php?346395-Converting-Heat-to-Nutrition&p=17419348#post17419348



Anyone know how much energy is generated by stuff like the tube worm in the deep dark sea? I'm wondering what kind of life could be supported by the energy produced by the slime and whatnot.