“The upshot of all this is that Mothra is going to have to add a lot of tracheal tubes to maintain a sufficient oxygen supply. Of course, the more of its volume that is tracheal tubes, the less is biomass that needs oxygen, but this implies that although Mothra may be heavy (because it’s big), its density is going to be very low — about the same as your average cotton ball.”

Zoologist Michael LaBarbera deconstructs classic monster movies at The Biology of B-Movie Monsters.