User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-1011548-20110828105142/@comment-4256715-20110829111059

that rathians don't set their lungs on fire is because they do not breathe the gas that they form the fire with from they're lungs but from special glands. the normal air in the lungs wouldn't burn so easily.... but the valve thing is also a quite good explanation.