The Retention of Heat in Surface Area to Volume Ratios

Rachel Hawkins, Chandler Brett Rostochil, Jillian D. Wormington


Researchers have noticed that northern subspecies of animals are usually larger in size than their counterparts within the same species living in lower latitudes or cooler climates. Bergmann's rule explains why this may be, and correlates susceptibility to temperature changes within animals to their surface area to volume ratios. Allen’s rule builds off of this idea and adds that these higher surface area to volume ratios are adaptations within animal species that contribute to an animal’s ability to either maintain or dissipate heat. In this experiment, we test this theory using clay models molded into spheres and cubes. Building off the knowledge that a sphere typically has a lower surface area than a cube of equal volume (made of the same material), we heat these objects on heating pads while recording their overall increase in body temperature to see if models with higher surface area to volume ratios really do heat up quicker than those with lower ratios. The results of this experiment support both Allen’s and Bergmann's rule, as most of the models with higher surface area to volume ratios (SA:V) experienced greater net increases in core temperatures. We can use this data to assume that the reason for the variance in size and shape seen among animals living in different types of climates is that their body structure is strategic in helping them either maintain or transfer heat. 

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