Breathy holes on Toruk

[Seze Mune]

Lol I like how u call it "bubbling exhuberance"  and believe me I am making the most of my young adult by running around and being goofy as any young blue skin should but yes we should get back on topic, despite how much u guys r making me rofl right now! Archaic and 'Eylan y'all should be comedians ur so funny! "nurse wheel mme into the day room" priceless  anyways

OK, just took my geritol and ate a bowl of prunes. I am ready for a night of conlang fun....

BLAH BLAH ON TOPIC how do the animals on Pandora bathe if they can't get past their chests in water?

First of all, how do we know Pandoran land animals bathe? Maybe they are like lions, who cringe at the thought of water. (Our lion Kenya will walk away from you if you simply slosh some water in a bucket. He will swim if it is desperately important....like his favorite ball is floating in the middle of the pond.)

The spiracles looks like they can close. This would enable the animals to submerge for brief periods. They also might have a different center of bouyancy when they swim, that keeps the spiracles out of the water. Or, maybe some animals can breathe through their mouth when they need to be in water.

According to Avatar Wiki:  The air inlets, or spiracles, face forward at the front of the chest cavity, like the engine intakes of a jet fighter. Induction of air is controlled by a cartilaginous operculum, or flap-valve. The banshee lung is a bellows like structure, inflated by rib movement, but unlike the lungs of terrestrial animals, it has unidirectional flow, venting aft through gill-like slits.

[`Eylan Ayfalulukanä]

According to Avatar Wiki:  The air inlets, or spiracles, face forward at the front of the chest cavity, like the engine intakes of a jet fighter. Induction of air is controlled by a cartilaginous operculum, or flap-valve. The banshee lung is a bellows like structure, inflated by rib movement, but unlike the lungs of terrestrial animals, it has unidirectional flow, venting aft through gill-like slits.

This is a very interesting adaptation, and is one I was not aware of. It also implies the lungs are very different than the lungs of 'Rrta animals, in that there is a linrear flow of gases through the lung.. This also implies that either the operculum, the gill slits, or some other structure has to act as a check valve, or the lungs would not be able to move air. This arrangement may move air over the gas exchange surfaces of the lungs a lot faster. This implies that either the lungs are fundamentally different (in the way gas exchange is actually done) in Pandoran creatures, or the oxygen concentration is lower than 'Rrta. This may also have something to do with a hydrogen sulfide detoxification system that almost certainly exists in the airway to mitigate against the corrosive effects of the H2S in the Pandoran atmosphere.

All that said, a scene in the film suggests that the terrestrial animals do inhale and exhale through their spiracles. I think it was a pa'li that they were showing breathing. Even there, a unidirectional flow would facilitate H2S removal. But looking at my detailed model of palulukan, I can see what might be exit slits.

I wonder what effect the high concentration of xenon in the Pandoran atmosphere has on respiration. The physics reason why there is so much xenon is probably interesting as well (xenon has a very low galactic abundance). Since xenon can form compounds under certain conditions, I wonder if it therefore plays a biological role.

[Clarke]

Xenon, being a noble gas, is pretty resistant to making compounds. Wikipedia lists its main compounds as all requiring fluorine, and it would be a very bad thing if Pandora's atmosphere had any significant amount of fluorine. (SInce it'd react with the H2S to form hydrofluorine and/or hydrofluoric acid.)

[`Eylan Ayfalulukanä]

Xenon, being a noble gas, is pretty resistant to making compounds. Wikipedia lists its main compounds as all requiring fluorine, and it would be a very bad thing if Pandora's atmosphere had any significant amount of fluorine. (SInce it'd react with the H2S to form hydrofluorine and/or hydrofluoric acid.)

Now, that would be truly nasty!

Thankfully, elemental fluorine is almost never encountered, and certainly not in a setting where living things are likely to be. I was also aware that the compounds that have been so far made with xenon have been fluorides of various sorts (called excimers). But when life gets involved, strange things can happen....

[Seze Mune]

According to Avatar Wiki:  The air inlets, or spiracles, face forward at the front of the chest cavity, like the engine intakes of a jet fighter. Induction of air is controlled by a cartilaginous operculum, or flap-valve. The banshee lung is a bellows like structure, inflated by rib movement, but unlike the lungs of terrestrial animals, it has unidirectional flow, venting aft through gill-like slits.

This is a very interesting adaptation, and is one I was not aware of. It also implies the lungs are very different than the lungs of 'Rrta animals, in that there is a linrear flow of gases through the lung.. This also implies that either the operculum, the gill slits, or some other structure has to act as a check valve, or the lungs would not be able to move air. This arrangement may move air over the gas exchange surfaces of the lungs a lot faster. This implies that either the lungs are fundamentally different (in the way gas exchange is actually done) in Pandoran creatures, or the oxygen concentration is lower than 'Rrta. This may also have something to do with a hydrogen sulfide detoxification system that almost certainly exists in the airway to mitigate against the corrosive effects of the H2S in the Pandoran atmosphere.

All that said, a scene in the film suggests that the terrestrial animals do inhale and exhale through their spiracles. I think it was a pa'li that they were showing breathing. Even there, a unidirectional flow would facilitate H2S removal. But looking at my detailed model of palulukan, I can see what might be exit slits.

I wonder what effect the high concentration of xenon in the Pandoran atmosphere has on respiration. The physics reason why there is so much xenon is probably interesting as well (xenon has a very low galactic abundance). Since xenon can form compounds under certain conditions, I wonder if it therefore plays a biological role.

I'm trying to understand the mechanics of vocalization.  Do you have any speculation on this?

[archaic]

Xenon, being a noble gas, is pretty resistant to making compounds. Wikipedia lists its main compounds as all requiring fluorine, and it would be a very bad thing if Pandora's atmosphere had any significant amount of fluorine. (SInce it'd react with the H2S to form hydrofluorine and/or hydrofluoric acid.)

Now, that would be truly nasty!

Thankfully, elemental fluorine is almost never encountered, and certainly not in a setting where living things are likely to be. I was also aware that the compounds that have been so far made with xenon have been fluorides of various sorts (called excimers). But when life gets involved, strange things can happen....

I doubt that there's much Hydrogen fluoride in the atmosphere, to quote wiki, "The gas can also cause blindness by rapid destruction of the corneas."
Both Quaritch and Jake are exposed to the atmosphere, Quaritch several times, but neither appear to suffer eye irritation.

[Clarke]

Actually, I think that's an inconsistency, since the density of H2S is given here as >1%. Also, since hydrogen sulfide is a chemical weapon, we've done toxicity tests on it, and found a dose of 0.1% (1000ppm) is immediately lethal.

IMO, that would be rather problematic for Quaritch.  

[Sezetirea216]

K guys lets get back on topic here

[Kamean]

When Grace come to the Kelutral, in the background are two Na'vi carrying the boat. And in the corner can be seen tapirus.

[Seze Mune]

And speaking of breathy holes on aytoruk....I haven't seen any description of how toruk or ikran can smell their prey.  Even animals which hunt by sight can smell their prey.  If spiracles are how toruks and ikrans take in the scent molecules via air, then what lies within which would enable a sense of smell?

[`Eylan Ayfalulukanä]

Actually, I think that's an inconsistency, since the density of H2S is given here as >1%. Also, since hydrogen sulfide is a chemical weapon, we've done toxicity tests on it, and found a dose of 0.1% (1000ppm) is immediately lethal.

IMO, that would be rather problematic for Quaritch.  

I don't think there is any HF floating around. It would quickly react with something and 'disappear'.

The H2S situation is another 'rotten egg'. Even with the breathing masks, a tiny amount of this dreadful stuff must leak through. So, everything on Pandora would absolutely stink to us, even with the mask on. One good thing is this is a strong incentive to wear your mask!

My well water is contaminated with natural H2S. It's fantastic water, and it it is under a lot of natural pressure (enough to properly operate all my appliances that use water!). But the H2S concentration was initially so high that the water left a yellow trail on the ground when it was running out of the casing during well development. It took me a few months to get a water treatment system built that would get rid of the H2S. During that time, I have plenty of evidence to suggest that H2S was attacking the copper plumbing. It caused some soft vinyl tubing to one of the sinks to actually swell shut. Thankfully, it does not attack PVC. Now, 10 years later, the H2S concentration is much lower, and the natural water is actually drinkable. (I have also been able to switch from ozone injection to atmospheric air injection, which saves me from running an expensive-to-maintain ozone generator.)

This is why I mentioned that there has to be some mechanism to deal with the H2S in the air. Since H2S breakdown is exergonic, some living creatures use it for energy generation. I suspect that Pandoran animals take advantage of this, and use the reactivity of H2S to remove it from the breathing air stream. (where the sulfur goes is something interesting to speculate about) It is also possible that the gas exchange surfaces in their lungs can prevent it from passing. They also might have a variation of enzymes that are resistant to H2S poisoning (keep in mind that their basic biochemistry must be almost identical to ours to allow a lot of what we see, and what is claimed in the film, to take place). In any case, it adds a lot of significance to a unidirectional, linear airflow through the lungs.

Vocalization is almost worth its own topic. They might have a tap off ot the 'clean air' in the lungs that they can pass through a sound-producing mechanism, and then exit through the mouth. From what we see, it looks like Pandoran animals vocalize through the mouth.

All this now begs an interesting question: If this complex adaption exists in many Pandoran animals, why do some have what appears to be 'normal' in-and-out breathing, like the Na'vi?

And all this begs another interesting question, and one that JC may have overlooked: If there is so much H2S in the air, why isn't it reacting with atmospheric oxygen and water vapor, and being removed from the environment? 2 H2S + O2 = 2 H2O + 2S (This is roughly the reaction I am using in my water treatment system.) This would also result in a fine yellow dust on everything over time. There would also have to be a constant regeneration of H2S and oxygen to keep this going. This implies that there must be some SERIOUS volcanism going on in other parts of Pandora (which would not be surprising for the moon of a gas giant)(and the ASG suggests that volcanism is the source of the H2S), or, there is something in the biology there that generates H2S as a metabolic byproduct.

On the sense of smell question, I bet the olfactory organs are located in the respiratory path, rather than in the head. Also, not all predators use smell to hunt, especially among birds. Raptors cannot smell prey from soaring heights. They have to see it. Most vultures (the American turkey vulture being a notable exception) cannot smell much at all. In fact, if you put an animal carcass in a tree, African vultures will never find it because their focus is on the ground.

[Clarke]

Vocalization is almost worth its own topic. They might have a tap off ot the 'clean air' in the lungs that they can pass through a sound-producing mechanism, and then exit through the mouth. From what we see, it looks like Pandoran animals vocalize through the mouth.

Is there a reason they'd have to filter the air they vocalize with? I don't see how H2S would make that much of a difference to being able to speak.

[`Eylan Ayfalulukanä]

They wouldn't necessarily have to use cleaned air for vocalization, but the air has to be under pressure. The place for the pressure to be built up in is the lungs. So to vocalize, the creature inhales, closes the exit valves on the gill slits, and the forces air through the vocalization mechanism with the breathing muscles.

There are other ways this could work. This just seems to be the simplest.

[Seze Mune]

They wouldn't necessarily have to use cleaned air for vocalization, but the air has to be under pressure. The place for the pressure to be built up in is the lungs. So to vocalize, the creature inhales, closes the exit valves on the gill slits, and the forces air through the vocalization mechanism with the breathing muscles.

There are other ways this could work. This just seems to be the simplest.

Since the breathing mechanism involving the lungs is unidirectional, I'm not sure how the pressurized air could be diverted.

Still, according to the Wikipedia site:

"The banshees are social animals, and communicate frequently, generating quite a din at rookeries and other communal areas.

Banshees were so named because of their piercing signature cry. This is only one of the banshee's many vocalizations and is thought to be a distant call defining territory.

"Other vocalizations include a warning hiss, which is part of an overall threat display posture, and a short sharp shriek which denotes stress or fear. There are also warning sounds, and other stress vocalizations, as well as more guttural vocalizations associated with social grooming and contentment.

"The banshee emits sound from its head, using the open mouth to focus the direction. However, it does not have a trachea in its neck, since it breathes directly into the chest cavity. It has instead, a tube running from the lungs up into the head which pumps air through the vocal organ, the syrinx. Chambers in the head amplify the sound before it is emitted into the mouth cavity for directional aiming. Some banshee vocalizations are emitted directly from the resonating cavity, when the mouth is closed. "

I suppose this is somewhat like a frog's croaking, but I really have trouble with visualizing this based on the vocalizations we hear in the movie.  Some of those screeches would be one heckuva croak.

[Seze Mune]

Syrinx: Ornithology . the vocal organ of birds, situated at or near the bifurcation of the trachea into the bronchi.

And Avatar/Wiki makes mention of the biological similarities between birds and ikran/toruk like creatures.

When I think of any of the loud ikran screeches emitting directly from the head cavities, I wonder how they avoid splitting headaches.

[Seze Mune]

Xenon, being a noble gas, is pretty resistant to making compounds. Wikipedia lists its main compounds as all requiring fluorine, and it would be a very bad thing if Pandora's atmosphere had any significant amount of fluorine. (SInce it'd react with the H2S to form hydrofluorine and/or hydrofluoric acid.)

Now, that would be truly nasty!

Thankfully, elemental fluorine is almost never encountered, and certainly not in a setting where living things are likely to be. I was also aware that the compounds that have been so far made with xenon have been fluorides of various sorts (called excimers). But when life gets involved, strange things can happen....

I doubt that there's much Hydrogen fluoride in the atmosphere, to quote wiki, "The gas can also cause blindness by rapid destruction of the corneas."
Both Quaritch and Jake are exposed to the atmosphere, Quaritch several times, but neither appear to suffer eye irritation.

The lungs aren't the only thing which breathes.  The skin breathes too.  What would the effect be on the respiration of the largest organ in the human body?

[Human No More]

And speaking of breathy holes on aytoruk....I haven't seen any description of how toruk or ikran can smell their prey.  Even animals which hunt by sight can smell their prey.  If spiracles are how toruks and ikrans take in the scent molecules via air, then what lies within which would enable a sense of smell?

Smell is just chemical sensors. They can be located somewhere else.

Xenon, being a noble gas, is pretty resistant to making compounds. Wikipedia lists its main compounds as all requiring fluorine, and it would be a very bad thing if Pandora's atmosphere had any significant amount of fluorine. (SInce it'd react with the H2S to form hydrofluorine and/or hydrofluoric acid.)

Now, that would be truly nasty!

Thankfully, elemental fluorine is almost never encountered, and certainly not in a setting where living things are likely to be. I was also aware that the compounds that have been so far made with xenon have been fluorides of various sorts (called excimers). But when life gets involved, strange things can happen....

I doubt that there's much Hydrogen fluoride in the atmosphere, to quote wiki, "The gas can also cause blindness by rapid destruction of the corneas."
Both Quaritch and Jake are exposed to the atmosphere, Quaritch several times, but neither appear to suffer eye irritation.

The lungs aren't the only thing which breathes.  The skin breathes too.  What would the effect be on the respiration of the largest organ in the human body?

Respiration isn't breathing
Also, no, skin doesn't 'breathe'. That's a myth perpetuated by a film.
H2S can penetrate skin, but only when exposed directly to skin when in liquid form. As a gas, it's perfectly safe as long as it isn't inhaled.

[Seze Mune]

You are right, not all respiration is breathing in the human sense since plants also do it. 

I guess what I meant is the migration of dilute compounds through the skin via ambient air or environment.  For example, several scientists in Japan investigated the influence of cycle exercise on acetone concentration in expired air and skin gas. To my way of thinking, gases involving the skin are not unidirectional. Apparently mustard gas and chlorine gas penetrate the skin and cause systemic effects.  In the case of mustard gas, the penetration is rapid and the result is not good.  Some of these mustard gases are sulfur compounds if I'm reading the material correctly.

I'm only guessing that prolonged exposure to air which is toxic to other tissues might have eventual systemic effects as its components are absorbed through the skin.  Especially if 'Eylan Ayfalulukanä is correct about the fine yellow powder coating everything.

Also, from what I've been reading in this very interesting article (   Mechanisms and Models of Skin Penetration ) Pandoran rain would be an aqueous vehicle for the transport of airborne compounds through the skin and into the system.

Very interesting stuff to speculate on, kefyak? 

[`Eylan Ayfalulukanä]

Wow! A lot to comment on.

In thinking the unidirectional breathing thing through, two valves are required in the lungs. Both are essentially 'check valves' and would work under air pressure. The intake valves are located near or in the spiracles. The exit valves, near or in the exhalation slits. On inhalation, the valves in the spiracles open, admitting air into the vacuum created in the lungs by muscular action. The same vacuum closes the exhalation slit valves, allowing the lungs to fill only through the spiracles. On exhalation, pressure created by muscles compressing the lungs forces the valves in the spiracles closed. the valves in the exhalation slits open under pressure, letting air leave the lungs. The operation of the heart is very similar to this.

Now, for vocalization, the exhalation valves are deliberately held shut by muscles, and the chest muscles build up pressure in the lungs. Another valve or regulator mechanism then admits pressurized air into the vocalization apparatus. That in turn produces sound through a number of well-understood mechanisms.

Vocalization can be very efficient-- and very loud. We have macaws and similar at our zoo. For their small size, they can let out a screech that approaches the threshold of pain, 10 feet away. I can sometimes here them 100 yards or more away. Lions have a very powerful vocalization. It is not as sensibly loud as the macaws, but if the lion roars into you (which I have experienced a number of times, and it is a cool experience), you can feel it in your bones. Under exceptional circumstances, I have heard a lion's roar from 7 miles away. Now imagine what an ikran can do, with a chest that is probably at least three times the size of a 'Rrtan lion. (Also, lions in particular have a very wide range of vocalizations, despite the fact their vocal mechanisms are optimized for roaring.)

Look up 'Banshee' on Wikipedia or something similar. It is very interesting.

H2S, even in the air, is reactive. The skin of Pandoran creatures has to protect against it. I would imagine that the gas also irritates wounds, and spoils meat rather quickly. (I kind of have a feeling that JC or whoever made that entry in the ASG may be off by at least an order of magnitude on the H2S levels in the atmosphere. It is a fictional movie, after all.)

Something tells me that rain on Pandora is very acidic. The H2S would react with water and form sulfuric acid. Also, after a rainstorm, the H2S level is probably a lot lower, and this may have interesting biological implications.

Concerning gas exchange through the skin, remember that our lungs have a surface area about the size of a tennis court. The skin may work for sme smaller animals. But as animal size increases, the internal-volume-to-skin-area increases, and the skin could never keep up with the needs of warm-blooded metabolism.

[archaic]

To breath in using spiracles, and out with exit gills, yet use a tube to the mouth only for vocalizing seems odd to me. Not sure how this might evolve.
But we do see a Nantang panting, pulling air in and out of it's mouth.

after a rainstorm, the H2S level is probably a lot lower, and this may have interesting biological implications.

Face palm. There is something about the air after it rains, it has been washed clean dust and pollutants.
Also some of the CO2 will have been dissolved (carbonic acid) as humans and other creatures use concentration of CO2 in the air to gauge O2, the air will feel as if it has a higher oxygen content.