Surface Area to Volume Ratio Affects the Rate of Thermal Heat Loss and Retention in Animals Found in Cooler Environments

Abstract

Thermoregulation is the ability of an organism to keep its body temperature within optimal boundaries, even when the surrounding temperature is different (French 2015). This characteristic is found in various homeotherms across the world. These mammals have the ability to hold their bodies at an optimal temperature based on their surface area to volume ratio. We further hypothesize that animals of the same species orient their bodies to be as spread out as possible in warmer environments to create a larger surface area to volume ratio, allowing for faster heat transfer and a cooler internal temperature. We tested our various hypotheses in two separate experiments, both set up in a controlled lab setting. In the first experiment, round clay molds were used to represent large (1.49 cm) and small (2.97 cm) animals. In the second experiment, identical clay molds were used to represent large (1.79 cm) and small (3.89 cm) animals, except we flattened these molds to act as an animal lying stretched out. In both experiments, the clay molds were submerged into ice and their internal temperature was recorded. In the first experiment, the larger molds maintained their internal temperature consistently, throughout five trials, better than the smaller molds. While in the second experiment, the flattened molds produced a cooler internal temperature at a faster rate than the round molds, throughout five trials. Therefore, animals with a smaller surface area to volume ratio maintain their body temperature at a better rate than animals with a larger surface area to volume ratio. This led us to the conclusion that animals orient their bodies to create a larger surface area to volume ratio, in order to create faster heat transfer and a lower internal body temperature. In this investigation, we explain why animals are shaped differently in cooler environments than animals in warmer environments, as well as the reasoning behind the orientation of their bodies.