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[Aviator CJ]

One day a while back, I was thinking about nether caps, specifically about the fact that they are naturally cold. I found myself considering how this could be possible.

I remembered that in high-school chemistry class, we learned about endothermic chemical reactions, ie. reactions that took in more energy than they released, thus reducing temperature in the immediate vicinity. I figured that something like this must be going on in the nether cap metabolism.

Thinking about such reactions, I realised that photosynthesis is in it's own way endothermic - it converts CO₂ into oxygen and (I think) glucose, using light as the energy source. My theory is this: Nether caps use heat to do the same job that plants do with light.

The more I thought about it, the more sense it made. There never seems to be any open-air link between the caverns and the surface, yet there is oxygen down there, as evidenced by fires down below from fire-based or -breating Forgotten Beasts. Also, the lower caverns should be much too hot for surface life, what with the magma sea just below it, but the nether caps act as heat-sinks keeping the temperature down.

What does anyone else think?

[tahujdt]

I think that the study of cavern ecosystems is cool , but Toady is the only one who actually knows.

[MenacesWithSpikes]

I don't know whether chemosynthesis can actually make anything colder, but it's a possibility for cavern ecosystems in general, particularly in cavern layer 3.  (Chemosynthesis exists in our own real world in deep ocean environments that never see sunlight.)

[Nil Eyeglazed]

Wow, another science nerd!

I think that makes perfect sense.  It does leave unanswered why plump helmets (et al) seem to require no energy source though. 

[Aviator CJ]

I was aware of chemosynthesis, I guessed that the nether caps managed to evolve themselves an enzyme that sped up the process so that it could be viable in a macroscopic life form.

The one thing I can't figure out is how the wood stays cold after being cut down, or made into a bed or barrel or whatever.

[Nil Eyeglazed]

I was aware of chemosynthesis, I guessed that the nether caps managed to evolve themselves an enzyme that sped up the process so that it could be viable in a macroscopic life form.

The one thing I can't figure out is how the wood stays cold after being cut down, or made into a bed or barrel or whatever.

Obviously, it's still alive.  Which makes sense, given that it's a fungus.  But what's it doing with the extra glucose (cellulose) it creates?

[tahujdt]

Obviously, it is leaking into the booze. That's why your dwarves are tantruming.

[Aviator CJ]

Wow, another science nerd!

I think that makes perfect sense.  It does leave unanswered why plump helmets (et al) seem to require no energy source though. 

I always thought that plump helmets worked just like normal fungi, getting their energy from the soil they are planted in, though that explanation falls short for things like the quarry bush, which definately has leaves, despite being an underground plant.

As for the extra glucose or cellulose or whatever, that's another good question. The extra oxygen is probably handy though. In fact, that could explain why my last Countess was so determined I make her so many anvils - she was euphoric from all the oxygen her nether cap bed was making   

[Tahlin]

Wow, another science nerd!

I think that makes perfect sense.  It does leave unanswered why plump helmets (et al) seem to require no energy source though.

It's a mushroom, It lives perfectly with just water.

[Xnidus]

Sorry guys,

But the mushrooms and other fungus are heterotrophic creatures, like the animals; but mainly saprophytic (they feed of organic residues), other are parasitic (like Athlete's Foot). Many others live in a true symbiotic relation with plants (see Mycorrhizas).

On the other hand, I think that the fungus used by the dorfs, like the plump helmets, are planted in a compost matrix (the destination of all waste residues of all fortress; including carpentry, booze and fecal residues), like our Agaricus bisporus cultivation (I don't know the true name (or mainly know name) of this mushroom in english), that is mainly planted with farm residues (straw, feces, wine production residues and others, in a high descomposition degree). Really, the fungus don't need light, they need a good organic source: trunks, fallen leaves, roots, feces, corpses... and high humidity degree.

Other option is that all the plant-like organisms of the caverns, are a symbiotic fungus-lithoautotrophic bacteria association. This bacterias used the minerals compounds of the soil and the gases of atmosphere to produce organic products; the fungus create a structure that support and protect the bacterial community, perhaps, synthesizing some toxins against the cavern grazers and other bacterial communities (the fungus have a very complex metabolism that create great toxins, see Amanita; and substances that stop the bacterial grow or directly kill this, see Antibiotics like penicilin). And this symbiotic association support all the cavern ecosistem.

I don't discard that some of these organism are bioluminescent that permit grow some and rare strange photosynthetic creatures in other "symbiotic" or "dependent" relation.

[kaijyuu]

Given some of the cavern creatures, I'm willing to accept some part of the ecosystem is literally based on magic. No need to follow the rules of thermodynamics completely.


Magma crabs are listed as able to eat rocks. I see no reason why plantlife and other creatures in the caverns can't do the same to gain energy, assuming they need it in the first place.

[BigFatStupidHead]

Lost my reply twice. Damn flaky network.

Basically, I was theorizing as to why nether caps are cold. Fungi are like icebergs, we only see a tiny portion of them; in this case, only the reproductive stalk for dispersing spores. The main body of the fungus can extend for miles below the surface, but the nether cap caverns are no colder than any other cavern, suggesting only the reproductive stalk produces cold. This cold may give their spores an advantage by inhibiting other spores and killing nearby organisms, providing an abundant fold supply for the spores to grow on.

There. Way less biology jargon the third time around.

[hjd_uk]

Nethercaps would remain cold once cut-down if the infra-red absorbtion was a part of the material structure of the 'wood' rather than an organic process.
The Piezioelectic / Photoelectric / Triboluminescence effect allows crystals to convert light to electricity and back.
Perhaps Nether-caps are blue because they are literally glowing blue, converting the ambient heat into light - which it uses itself for photosynthesis.
Being shut off from light in dark caverns, it evolved to create its own light.
Obvioulsy there would be a significant efficiency loss in converting heat to blue light, but that just confirms that the Nethercaps need to absorb a lot of heat for a faint blue glow.
It also means that there is light in the caverns, just a very faint blue glow that humans would barly be able to see, like dull moonlight or less - cavern dwellers or Dwarves of course have excellent dark vision.
Nethercaps : Light-bulbs of the underworld ?

[Sadrice]

Unfortunately, unless you have very intense radiation, fluorescence (absorbing a photon of one frequency and emitting one of a different frequency) always involves emitting a longer wavelength (lower energy) photon than the one that was absorbed.  Meaning that to get a blue glow, it would need to absorb violet light, or more likely, ultraviolet.  Absorbing thermal infrared would only get you far infrared or microwaves.  To absorb infrared and emit blue light would mean you would be adding energy to the photon, so you couldn't possibly at the same time get energy to do useful work from it.  This process would in fact be endothermic, but it would not be thermodynamically favored, and wouldn't happen. Under super intense radiation conditions, a molecule can absorb two photons and emit one of higher wavelength, but that's not applicable here.

When analyzing whether a reaction will be spontaneous or not, you use an equation that depends upon the thermodynamics and the entropy of the process.  Since this process is endothermic, it would need to cause a fairly significant increase in entropy in order to happen.  Photosynthesis, and any other reaction that takes simple compounds and turns them into more complex, energy containing compounds, is antientropic.  Any process that is both endothermic and antientropic will not go forwards unless you add quite a bit of heat.  Maybe nethercaps have found a way to use magma to drive their chemistry, and that's why they're only found in the third cavern layer?

[MenacesWithSpikes]

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