October 18th, 2010

no sympathy for falling ants

Biomechanics @ wiki:

If an animal were scaled up by a considerable amount, its muscular strength would be severely reduced since the cross section of its muscles would increase by the square of the scaling factor while their mass would increase by the cube of the scaling factor. As a result of this, cardiovascular functions would be severely limited.

In the case of flying animals, their wing loading would be increased if they were scaled up, and they would therefore have to fly faster to gain the same amount of lift. Air resistance per unit mass is also higher for smaller animals, which is why a small animal like an ant cannot die by falling from any height.

As was elucidated by Haldane, large animals do not look like small animals: an elephant cannot be mistaken for a mouse scaled up in size. The bones of an elephant are necessarily proportionately much larger than the the bones of a mouse, because they must carry proportionately higher weight. Because of this, the giant animals seen in horror movies (e.g., Godzilla) are unrealistic, as their sheer size would force them to collapse. However, it’s no coincidence that the largest animals in existence today are giant aquatic animals, because the buoyancy of water negates to some extent the effects of gravity. Therefore, sea creatures can grow to very large sizes without the same musculoskeletal structures that would be required of similarly sized land creatures.

I’d guessed it was something to do with the scaling of physical laws. But here it is explained rather elegantly.

I’d love to see a biomechanically accurate Godzilla.


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