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The bonegrass fields are full of other life, despite their dangers. Lots of insects, some birds, and even a handful of reptiles have adapted to the paralytic nature of the air in order to reap the rich rewards offered by the deathly white foliage. Of all of these creatures the most advanced by far are the fleshmoles.

Rather than adapting to the neurotoxins emitted by the plantlife the fleshmoles (actually a branch of naked mole rats) have an alternate strategy:

They rarely breathe fresh air.

Fleshmoles don't surface unless there is prey that has been ensnared by the bonegrass, and even then they tunnel directly up through the ground into the flesh of whatever has fallen (causing excruciating pain if the prey hasn't already died). They're adapted to deal with high CO2 concentrations and the noxious atmosphere of their underground hives (A matriarchal eusocial structure keeps fleshmole colonies together), but of course occasional O2 injections are required.

To this end weak or old fleshmoles are driven to the surface, where they take a huge lungful of air, become paralyzed (neatly plugging the hole and removing the paralytic agent from the air they breathed in), then are dragged back down and rapidly consumed by their brethren. Fleshmoles also burrow into the chest cavities of larger prey in order to suck down as much O2 rich flesh as possible.

The question is this, given that I'm not particularly hot on my rodent biology:

Is it possible for such a colony to maintain a workable O2 supply, given that they're fairly well optimised for high CO2 life?

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You might want to read a little bit about anaerobic bacteria, which don't need oxygen to survive. These moles could have evolved from them, but you'll have to rethink things like blood. – Lacklub Mar 21 at 13:40
    
Why would they not just adapt to the paralytic? Something that has involved to live in such an environment would have taken the path of least resistance; becoming "immune" to the paralytic in the air. – DJMethaneMan Mar 21 at 13:42
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Wouldn't the lungs of creatures in the bonegrass be full of bonegrass toxins, anyways? Plus, if the creatures are paralyzed, their blood will rapidly deplete the oxygen in their lungs, leading to asphyxiation, death, and oxygen poor air for the moles to breathe. It might make more sense if there's some sort of filtration (maybe even the bonegrass roots?) that causes the mole tunnels to be oxygenated, but toxin free. – ckersch Mar 21 at 15:32
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@pyrulez: This entire ecosystem is based around 'Bonegrass'. It's not trying to be full of unicorns. Even if it were they'd probably be the kind that gore you to death and wear your skin as a hat.... – Joe Bloggs Mar 21 at 16:00
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"It's not trying to be full of unicorns." Well, technically since the entire ecosystem seems to be parasitic in nature, it seems that it would love to be full of unicorns. Especially if the bone grass likes Keratin. – PyRulez Mar 21 at 16:36
up vote 23 down vote accepted

For mammals... this could be a problem.

A pretty average human being(62 kg) uses about 550 liters of pure oxygen per day(at sea level pressure). So call it 9 ish litres per kg.

A single naked mole-rat is about 35 grams.

A colony is 20 to 300 individuals, with an average of 75.

So an average colony of 75 might weigh in at about 2.5-3.0 Kg of mamal-flesh.

They're extraordinarily long-lived for a rodent of their size (up to 31 years)

Small rodents tend to use more, not less oxygen by weight (more active) but lets make some generous assumptions. Lets assume they use 10% as much oxygen by weight as humans.

Your collony still needs 2.7 litres of pure 02 per day or 13.5 litres of normal air (20% oxygen) assuming they use it perfectly somehow.

From this we can conclude that this is not a workable stratagy:

weak or old fleshmoles are driven to the surface, where they take a huge lungful of air, become paralyzed (neatly plugging the hole and removing the paralytic agent from the air they breathed in), then are dragged back down and rapidly consumed by their brethren.

They live too long, their lungs are too small and it's just not gonna work. They couldn't provide a tenth of the air needed even with generous assumptions.

But if I remember you talked about how your victims are left alive. The air in their lungs is not a good option, it's contaminated by the spores just like the outside air.

So lets try another option.

Again, lets steal from real life organisms.

enter image description here

Real paracites need oxygen, how do they get it?

They absorb it from their host, often direct from the blood. Your victim has a perfectly good set of lungs and they're going to be alive for quite a while(longer if nothing burrows into their lungs)

So your moles could be adapted to burrow into the flesh(careful not to cause lethal harm), find big arteries close to the heart/lungs where it's rich in oxygen and to them filter lots of oxygen from the blood and to somehow feed it back to their kin bellow using the victim as a living oxygen filter.

Perhaps if desperate and lacking prey for a long long time the moles might sacrifice one of their own to use the same trick, one of them breathes while the others filter oxygen from it's blood bellow.

This leads on to some grim conclusions.

It's going to be in the moles interest to keep the victim alive for as long as possible.

Too much bonegrass growing up through them will kill too fast. So the moles could be chewing away the roots of some of the young bonegrass to keep it from killing the victim quickly. The bonegrass wants to kill you fast. The moles want to keep you alive for as long as possible.

Indeed, weirdly, if they have access to lots of calories but not much oxygen it could be in their interest to feed sugars into your blood while taking oxygen out.

To stop you dying from infections they might even release antimicrobials as they chew into your flesh.

(additional reason for people to enter the bonegrass, fleshmole teeth could have "venom" sacks containing potent antibiotics)

They also might carefully feed on fatty tissue, avoiding blood vessels, again to keep their victim alive for as long as possible.

There are some far more practical options for filtering air... but they're not as fun as absorbing it from the blood of still living hosts.

Now, there's also another possible use for your victim. A nice warm place for baby fleshmoles and similar parasites to grow.

Here's a species of wasp which lays it's eggs inside still-living hosts.

♫It lands on caterpillars 
It lays it's eggs inside
To make sure that the meat's fresh
It keeps the things alive

All things bright and beautiful...♫

Keep the meat fresh

Some wasps have an even more disturbing effect on their victims.

Once the babies have eaten their way out through the hosts flesh the host's behavior has been altered by the parasite and the caterpillar spends the remainder of it's life trying to protect the parasites.

https://youtu.be/7UkDMrG6tog?t=8

So for added creepiness, imagine someone getting paralyzed, fleshmoles eat through their flesh but before they die the wind changes direction, the amount of paralytic poison decreases and they make their escape.

They have a few baby fleshmoles under their skin but rather than wanting to cut them out and destroy them the host feels a strong compulsion to care for them because the fleshmoles have released a hormone that hijacks the normal instincts to protect your children.

Someone is rescued from the bonegrass and the fleshmoles. The town rejoices. But the following week they're found carrying around a blanket filled with a squirming mass of infant fleshmoles treating them like a baby and feeding them chunks of raw meat.

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Gross but cool 😎 – Aarthew III Mar 21 at 14:46
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Wow. That took the level of grim in the question and just boosted straight over it. Well done!!! Also: +1 just for the numbers at the start. – Joe Bloggs Mar 21 at 15:18
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@JoeBloggs Flesh Scarecrows. The moles take the paralyzed creature. They build a mound and prop them up, carefully dismantling their lower torso. Specialist moles (or a symbiotic plant they cultivate) mix their circulatory system with the dismantled lower limbs of the flesh scarecrow, extracting oxygen and sharing it with the colony. Sugars and antibiotics are fed into the flesh scarecrow to keep it alive and filtering oxygen for the colony. The vertical orientation reduces the amount of bonegrass it can be punctured with, and lures predators and/or same species near. – Yakk Mar 21 at 15:35
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How do living hosts filter neurotoxins? Wouldn't there be neurotoxins in their blood? – PyRulez Mar 21 at 15:47
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This is a really great answer because it's pretty parallel to what mole rats already do. Though a lot less grim, they do keep their "prey" (large tubers in this case) alive and growing as they carefully gnaw away some of it for food. – Deolater Mar 21 at 19:37

They would most likely arrange their burrows similar to how terrestrial burrowing creatures do so that there is enough air-flow through them to survive. Perhaps they even have "breather" tunnels that extend away from the grass fields and allow fresh air to flow in even when the grass starts spreading toxins.

The moles could have a hibernation-like state when oxygen drops too low or toxin levels too high. Effectively they become dormant and conserve their oxygen until the event passes and the fresh air from their breather tunnels wakes them up again to continue their lives.

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+1 : for the breather tunnels. These tunnels could radiate out from the main burrow in all directions, surfacing beyond the bonegrass field where they rise up like ant-hill towers. These towers would have vent openings pointing away from the field so that only winds coming from beyond the fields would enter the tunnel system. The towers might become a warning sign to travellers indicating where fields are located, allowing them to stay away and upwind of the dangerous areea. – Henry Taylor Mar 21 at 14:32
    
definitely +1 for the breather tunnels. That way even if the wind does change and they unexpectedly get a huge dose of the paralytic they can happily sleep it off, safe and snug in their burrows. – Joe Bloggs Mar 21 at 14:40
    
Instead of tunnels, they could create tower-like towers, much like termites, which would allow for fresh air above the CO2 layer to sink in and go through the actual tunnels where the moles live. – Sara Costa Mar 21 at 16:21

If they're subterranean they wouldn't disturb the grass and trigger the toxins the way a passing surface animal would. Also the air in their tunnels would have been filtered by passing through the relatively porous ground above them making it potentially safe to breathe.

Or:
If they've evolved around the bonegrass they're largely immune, but they do need to take a nap if a large animal triggers a lot of toxin near an open tunnel. Much like the grasshopper mouse and the scorpion, or the mongoose with snake venom.

Once you start introducing other creatures also living on the bonegrass victims then your fields are going to need to be quite bloodthirsty.

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Nice, the ground could be like a filter. – Aarthew III Mar 21 at 14:23
    
+1 for making the ground a filter, but make it an element in the soil, possibly something excreted by the flesh moles. That way, if science every evolves among the inhabitants of this planet, they will have a clue as to how to nullify the airborne poison. – Henry Taylor Mar 21 at 14:35
    
Any idea how close the tunnels would have to run near the surface for air to effectively reach the fleshmoles? It'd suck if they had to be near enough to the surface that a collapsing Gomorrah deer could crush them... – Joe Bloggs Mar 21 at 14:43
    
@JoeBloggs, that'll depend on the consistency of the soil the bonegrass likes to grow in, density of roots, whether the roots like to spread into a mat or go deep down. I'd assume growing wide and shallow as a mat as you're absorbing surface nutrients rather than deep, so you could have a very tough surface layer allowing shallow tunnels. The roots themselves could reabsorb toxin that filters down through them. – Separatrix Mar 21 at 14:48
    
@JoeBloggs, should also say, burrowing animals are very sensitive to vibration. It would be no problem for them to avoid the footfalls of surface animals to avoid predators/being crushed by falling deer along with the high dose of toxins that a surface animal would release, then move in once the air had cleared after the fall. That way there's almost no risk of being crushed in the tunnels. – Separatrix Mar 22 at 12:48

Since you mentioned CO2, I'm guessing you are using this answer from Tim B.

If so, then think of dolphin moles. To store up large stores of CO2 while still being able to breathe may require the bone grass to go on a crazy oxygen converting frenzy. This would create an abundance of outside oxygen while the plants stored up CO2. Only during this time do the moles appear for air. The bone grass has learned to ignore the moles as the miles always disappear before they can pump out sufficient CO2. The mole dolphins don't have to surface for a while and are alive and well. If you want the moles to tunnel into people's lungs, it would be a bit impractical as the person collapsed because it has too much CO2... Perhaps this is what the mole eats?

Also just a side note. The CO2 could be used as a defense against fire. Whenever you try to light the bone grass, it suffocates the fire!

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actually I mentioned CO2 because the mole rats would be living in a fairly closed system with little ability to recycle the CO2, so the 'getting air from lungs' requirement is still there. I hadn't even noticed someone else had asked a bonegrass question! – Joe Bloggs Mar 21 at 14:59
    
@Joe Bloggs ah, ok. Could you explain how the grass works other than paralytic pollen? – Aarthew III Mar 21 at 15:04
    
I wasn't planning to. Pollen (or similar free-floating bodies) laden with paralytic neurotoxins sounds like a pretty reasonable bit of biology to me, given how little of certain chemicals are needed to completely incapacitate or kill even large mammals. I like your question though. – Joe Bloggs Mar 21 at 15:24

This is actually a real issue for termites. I know someone who studies this question - How do termites ventilate their mounds? After all, a bunch of termites live underground. I can't find a source now, but if I recall the biomass of a termite colony is comparable to that of a sheep - not warm blooded, but still that's a large O2 requirement.

Let's think about the pollen. It gets carried by the wind, but it is heavier than air, so it doesn't get very high. In fact it's in the evolutionary interests of the grass to select density (and shape) such that the concentrations are highest in the level of the terrestrial animals walking around. So the pollen cloud won't get much over 6 feet high.

Your moles have a few big termite mound-like structures in the middle of the field. The mounds exchange air from within the chamber and above the layer where the pollen lies. They can even come to the top, meerkat like, and look around for where some victim has fallen. Then they tunnel over to it.

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Perhaps instead of them getting the oxygen from only their victims, they also have some kind of filter in their lungs that filters out CO2 and let's only oxygen in. However, over the life time of the mole, the filter degrades, eventually to the point where it cannot keep itself alive. Then it is out out to pasture.

But why skip out in a good meal? More oxygen can be found in the blood of their victims, which means they don't have to waste filters during feeding time. Which means eat the lungs and arteries last, so they can provide you with oxygen while you burrow through the victim's living flesh. Even if the creature hAs inhaled a lot of CO2, it still takes less filtering and is nice and yummy for the flesh moles. And when their brethren become to old to efficiently filter out the CO2, it is time to feed...

Because fo such creatures you just can't get enough oxygen by simply draining it from the living blood.

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filters? I think it's easier to have some kind of bacteria inside its lungs that breathes CO² and farts O² out :) the bacteria get some Carbons and humidity and the host gets some nice clean farted O² :D – Mr. Derpinthoughton Mar 22 at 14:39

Your beasts' should be a sustainable ecosystem for bacteria that make O² out of byproducts produced by your beasts.

There's a bacterium that does that, it's called Methylomirabilis oxyfera, it eats methane and oust oxygen, perhaps this kind of bacteria can live in your beast's digestive system consuming methane and producing oxygen so your beast would fart oxygen and breathe it in :D

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