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For a long time biologists have assumed that reptilian scales are an adaptation to decrease water loss and regulate heat transfer.While the structure of reptilian scales has been investigated, the function that they serve has been examined less carefully. In the article A Scaleless Snake: Tests of the Role of Reptilian Scales in Water Loss and Heat Transfer, Paul Licht and Albert Bennett test the assumptions that scales are an adaptation to reduce water loss and aid heat transfer.

To investigate the hypothesis that scales are important in regulating water loss and heat transfer, the authors experimented on one normal hatchling gopher snake and one scaleless hatchling gopher snake. In one series of experiments, the authors measured evaporative water loss and oxygen consumption at 28 degrees C. Oxygen consumption is correlated with an animal's metabolic rate, a measure of baseline energy requirements (Defining Terms) . To take these measurements, the researchers placed each snake in a separate container. Dry air was then pumped through the container. Gravimetric and humidity measurements of the air going into and out of the chamber allowed the authors to determine the amount of water lost by each snake. Measurements of the oxygen in the air entering and leaving the tube were taken to determine the oxygen consumption of the two snakes.

The authors also measured convective heat transfer, both as rates of heat gain and of heat loss. To measure heat gain, they cooled the snakes to 15 degrees C. and then placed them in a cabinet at 33 degrees C. To measure heat loss, the authors heated the snakes to 32 degrees C. and then placed them in a cabinet at 15 degrees C. A constant wind speed was maintained in the cabinet in both cases. The authors measured the temperature of the snakes using a thermocouple inserted into each snake's intestine. These measurements enabled the authors to determine the rates of convective heating and cooling for each of the snakes (Building Coherence) .

The authors found that there were no significant differences in the rates of water loss, metabolism, heat gain or heat loss between the two snakes. They also found that the rates of heating roughly equaled the rates of cooling for each snake. This finding differed from the findings of other studies. Thus, the authors concluded that the scales of reptiles might not play an important role in regulating water loss or convective heat transfer. They allow for the possibility that scales might play a role in radiative heat exchange, but stress caution in interpreting features as adaptations (Elements of a Good Summary) .

Licht and Bennett's experiments contribute to our understanding of the function of reptilian scales. The authors showed that there is reason to suspect that the adaptive function that is assumed for scales may not be an actual function of scales. This paper also serves, on a broader level, as a reminder that scientists need to be cautious in drawing conclusions about the adaptive functions of various features of animals and plants. It is very easy to create adaptive explanations for structures, but, as the authors show, the validity of these explanations should be tested experimentally. The need for such experimental testing is perhaps the most important conclusion that can be drawn from this paper.