Aside: Countershading is a coulour pattern observed on many animals where those parts of the body that are naturals illuminated have darker pigment, and lighter pigmentation on those body sections that are naturally shaded. One of the main hypotheses for the evolution of countershading is that it makes it harder for predators to find prey because they blend in to their background better (i.e., it’s a form of crypsis). Hannah Rowland has done some great work on the adaptive value of countershading check out her publications and website. Here is a publication that used a similar design to the one I used:
Rowland, H. M., Cuthill, I. C., Harvey, I. F., Speed, M. P., & Ruxton, G. D. (2008). Can't tell the caterpillars from the trees: countershading enhances survival in a woodland. Proceedings of the Royal Society of London - B, 275(1651), 2539–2545
I made 4 types of caterpillars: solid green-no eyespots, countershaded-no eyespots, solid green-eyespots, countershaded-eyespots. Here are some photos to give you an idea:
I'll post more details about results of this work later, but one possible criticism of this design is that caterpillars may not spend a substantial portion of their time on tree branches. Arguably, caterpillars spend most of their time on leaves.
*Update: This work is now published, and I you can find out more in this more recent post. Also, the full citation for this work is below:
Hossie, T. J., Sherratt, T. N., (2012) Eyespots interact with body colour to protect caterpillar-like prey from avian predators. Animal Behaviour 84(1): 167-173, doi:10.1016/j.anbehav.2012.04.027
Today I observed 2 different caterpillars on the branch of the tree they are currently feeding on. I found the first one apparently resting on the branch, I spent some time watching it then eventually I decided to get my camera. When I got back it had moved to a leaf, but a few moments later I saw another one travelling along a branch. I don't have an SLR camera yet so without a manual focus on my digital camera it was hard to get good photos, but here are some:
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