Have you ever gone to the zoo and been unable to find what was in a particular exhibit? This is because of the animal’s capability to camouflage. Green tree frogs (Hyla cinerea) are one of the few animals capable of this. Through evolution the green tree frog has acquired the ability to change colors, but to what extent? One theory that can be used considers the costs and benefits that result from certain acquired mechanisms. The evolutionary theory explains the idea that organisms develop mechanisms that are energy efficient which then yield maximized benefits as opposed to costs. If the green tree frogs’ camouflage mechanism follows this hypothesis, then green tree frogs would only change to colors found in their natural environment. By doing so, they could conserve energy for other important processes, such as reproduction. Their focus on reproduction allows them to continue to pass this trait onto their offspring increasing the chances of the species survival. We tested the degree of color they were capable of changing; assuming that the frogs were able to change colors similarly to chameleons, but maybe not to the same degree of color range.

To test our hypothesis we placed 5 green tree frogs into different colored environments (red, navy, green, gray, and brown) made up of t-shirts in 5 Tupperware buckets. Each frog had a consistent light green shade and a white band across each of their faces. We took the frogs from their original enclosure of a large aquarium with green moss and put each frog into one of the colored environments (buckets). We kept temperature, moisture, food, and lighting conditions the same for every frog. We measured the color of the frogs after 10 minutes, fifty minutes, and eight-teen hours and compared these colors to the frogs’ color prior to testing. In order to measure the degree of color change, we ranked the frogs in order from the lightest to darkest shade. We ran each trial 3 times, first returning the frogs to the aquarium for 6 hours after each trial so they could regain their original color and then making sure frogs were switched around each time we returned them to the buckets. We predicted that the frogs would change to brown and gray shades if they remained in the corresponding colored environments (shirts); we came to this prediction because those are "natural" colors. This meant that the frogs would remain their original shade of green if they were in the "unnatural" environments (red and navy).

Our results showed each of the frogs were only capable of changing shades of green. The shade often became so dark it had a brown tint to the color, but they never took on the actual colors (gray and brown) that we had originally predicted. The white bands across the eyes of each frog were not affected by the changing environments; however, they became even more distinct with darkening body of the frog. We compared the frogs after each test to decide which had the greatest color change and ordered them from 1 to 5 (1 being the lightest green). The average rankings of the three trials ran were as follows: Red 2.7, Navy 4.0, Brown 3.3, Gray 3.7, and Green (control) 1.3. Our control did not remain the lightest for every trial; twice the frogs were found on the side of the clear container which resulted in them being even lighter than when found in the green (control) environment.

Considering the frogs didn’t completely change their shade to match their environment, our predictions did not match our results. Our hypothesis and prediction called for a complete change in color but our results only showed a change in shade of green. There were many problems with our experiment; we only had shirts covering the bottom of the environment. If the frogs were not completely embedded in the shirt they became even lighter than our control (green shirt). Another factor that could have affected the results was the amount of light the frogs received. Even though there were many holes for the passage of light, it was still dark in the container. Additionally, the shirts were constructed differently and made of different materials. Time is another factor that could have changed our results. If we ran the trials longer, different outcomes could have occurred. Ideally, we would have dyed some of the moss different colors, because the moss is a regular environment for the frogs. After looking at other research performed, one abstract in particular, showed color changes of the green tree frogs due to predation factors along with temperature variables. (King, R., Hauff, S., Phillips, J., Copeia. Vol. 1994). From the results of our experiment we propose an alternative hypothesis. We feel the frogs must be physically touching the colored environment in order to change. We do not think the frogs are capable of actually changing their original color, but merely become a darker shade of green in a darker environment, regardless of how natural the color of the environment may seem.