Breathy holes on Toruk

[Clarke]

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.

Oh dear. So the Eastern Sea isn't going to be quite as pleasant as the name sounds? 

[`Eylan Ayfalulukanä]

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.

When you think about it, it is really not all that different from the inhale/exhale system. It is kind of a 'conservation of bodily openings'-- the less openings to the inside of the creature, the less problems there can be. It also makes it easier to eat quickly, an advantage for carnivores when there might be some other creature waiting to steal your hard-won kill. (Generally not an issue for palulukan, but 'food for thought').

Now, the panting on aynantang could be a problem because as I see it, there would not be much H2S protection in the mouth/throat if they breathe through spiracles. The panting might have been something added to gives the viewer a connection with 'Rrtan canines. (Canines have a highly evolved mechanism for cooling blood to the brain through their nose, which partly explains their long muzzles.)