Air, as a gas, will be displaced by the *volume* of a solid, in this case, an organism. And, sure, as the organism increases volume by some means (except consuming air), it will displace more of the gas, which is the air.
Since E = mc^2, how can photons be massless? If a photon has no mass, then, according to Einstein's formula, its energy is given by E = 0 x c^2, which is 0. Yet, photons do have energy. This seems to be a complete contradiction. Please explain! Thank you.