Michael C. LaBarbera analyzes The Biology of B-Movie Monsters, starting with scaling:
- The magnitude of surface tension forces is proportional to the wetted perimeter (a length); a water strider needs long feet, not big feet, to skate on the surface of a pond.
- Adhesive forces are proportional to contact areas; geckos need broad, flat feet covered with millions of tiny setae to walk on the ceiling.
- Gravitational or inertial forces are proportional to volume (assuming that density is constant); a bird that flies into a window may break its neck, but a fly that flies into a window will bounce without injury.
More:
The same dependence on different aspects of geometry holds for functional relationships. The forces that can be produced by a muscle or the strength of a bone are in each case proportional to their cross-sectional areas; the weight of an animal is proportional to its volume.Physiological relationships are not exempt. The rate at which oxygen can be extracted from the air is proportional to the surface area of the lungs; the rate at which food is digested and absorbed to the surface area of the gut; the rate at which heat is lost to the surface area of the body: but the rate at which oxygen or food must be supplied or the rate at which heat is produced is proportional to the mass (i.e., volume) of the animal. If an animal performs well at any given size, size change alone implies that these related functions must change at different rates, since their underlying geometric bases change at different rates; if the animal is to be functional at the changed size, either functional relations must change or shape must change. Monster movies have extensively explored these scaling relationships, albeit usually incorrectly; knowing the true relationships often puts the entire movie into a new light.
It’s a lengthy piece. I’ll leave you with one passage on The Incredible Shrinking Man:
Because of these relatively larger surface areas, he’ll be losing water at a proportionally larger rate, so he’ll have to drink a lot, too. We see him drink once in the movie — he dips his hand into a puddle and sips from his cupped palm. The image is unremarkable and natural, but unfortunately wrong for his dimensions: at his size surface tension becomes a force comparable to gravity. More likely, he’d immerse his hand in the pool and withdraw it coated with a drop of water the size of his head. When he put his lips to the drop, the surface tension would force the drop down his throat whether or not he chooses to swallow.