Sunlight energy harvest by animals

12 02 2011

Sunlight energy harvesting is considered one predominant option to solve the energy needs of humankind without destroying our natural environment. We all know that plants collect sunlight energy and produce chemical fuels that are used for growth and metabolism. Such chemical fuels furthermore feed the entire biosphere, and the arcaic underground reserves of plant-processed solar energy are the main energy input of humans.

Humans can now directly harvest solar energy using solar cells that convert photons to electricity. The rest of the animals get the energy for metabolism and motricity from food. An important question is: can animals get their energy directly from sunlight? This would point out efficient solar energy conversion systems designed by evolution that could serve as models to develop our own conversion devices.

A paper by Arie Zaban and coworkers in Naturwissenschaften adresses just this question. Zaban is a professor of Chemistry at Bar Ilan University, Israel, that developed many pioneering concepts of dye-sensitized solar cell research. He is also the Director of the Institute of Nanotechnology and Advanced Materials at Bar-Ilan. It has been observed  that the oriental hornet (Vespa orientalis) shows a peak of activity in the middle of the day. It was also established that the epicuticle, that forms the characteristic stripes of the hornet, absorbs solar radiation. Light eneters the epicuticle, which exhibits a grating-like structure, and continues to pass through layers of the exo-endocuticle until it is absorbed by the pigment melanin in the brown-colored cuticle or xanthopterin in the yellow-colored cuticle. The objective of the article is to explore if some form of solar energy harvesting is performed in the cuticle.