Biological Strategy
Pigments Absorb SolarEnergy
Oriental hornet
Leon Wang
Image: Stavros Markopoulos /
Chemically Generate Flow of Electrons(Redox)
Electron flows, or electron transport, is a critical step in numerous biochemical pathways. For example, the flow of electrons along the electron transport chain between membrane-bound proteins of mitochondria during cellular respiration or the chloroplast during photosynthesis triggers a flow of protons across the same membrane. This flow provides the energy for cellular processes similar to the flow of water across a hydroelectric dam.
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Capture, Absorb, or FilterEnergy
Energy is naturally available in many forms, including kinetic, potential, thermal, elastic, radiant, chemical, and more. All living systems require energy to carry out their many activities, and have developed strategies appropriate to one or more of those forms. For example, some plants maximize their surface area available for capturing radiant energy from the sun while others have strategies to focus scattered light onto photosynthesizing areas.
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Modify Electric Charge
Harnessing the power of electricity can be a powerful way for organisms to get energy. An electric charge can be positive or negative. When matter with an electric charge is near other charged particles, it will either be ‘repulsed’ or ‘attracted’ to the matter based on the charge. From electric eels to oriental hornets, learn about the different ways organisms use electric charges to their advantage.
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Modify Electron Transport
Electron transport is essential for helping organisms to produce energy and survive. Several species can modify the movement of electrons in different ways, allowing them to survive in a variety of conditions.
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Store Energy
Once a living system captures energy or transforms one energy form into another, it must frequently save that energy for future use. But energy is difficult to store in some forms. So living systems need strategies to either use energy quickly, or to convert it from forms that are difficult to store (such as electrical or kinetic) to more storable forms. For example, grasshoppers store energy as potential energy in an elastic material in their tendons. When they need to jump, that energy converts into kinetic energy, providing the force needed to escape predators.
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Insects
Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies
Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.
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Pigments in the oriental hornet’s cuticle absorb solar energy that is turned into electrical energy.
Typically, wasps and hornets are more active during the early morning as they begin their daily activities. In contrast, the oriental hornet is most active during the middle of the day. It is a social insect that nests underground and correlates its digging activity with the intensity of the sunlight.
As it turns out, there is a good reason why these hornets tend to work in direct sunlight. These hornets have an outer layer (cuticle) that actually allows them to absorb sunlight. The brown and yellow colors of the oriental hornet not only serve to warn potential predators, but also contain s that harvest solar energy. The banded sections have multiple layers that get successively thinner and sandwich the pigments. The brown cuticle has about 30 layers while the yellow cuticle has roughly 15. Scientists have found that the outer brown layer is covered in grooves that act almost like gratings that help trap light, allowing the rays to funnel inward for better absorption. The outer yellow layer is covered in oval-shaped bumps that increase effective surface area for absorption. Both of these areas exhibit antireflection and light-trapping properties, enhancing the absorption of light in the cuticle. The role of the layers getting successively thinner is still under investigation.
The sunlight that these hornets capture is likely converted into electrical energy. There exists a voltage between the inner and outer layers of the yellow stripe that increases in response to illumination. The harvested energy may be used in physical activity (digging or flight) and temperature regulation. It even seems to provide enough energy to carry out metabolic functions similar to the (producing or filtering enzymes and sugars). The enzymatic activity in these regions has been shown to decrease when the hornet is exposed to light, allowing it to conserve its energy.
This summary was contributed by Leon Wang.
Last Updated March 23, 2020
References
Journal article
Solar energy harvesting in the epicuticle of the oriental hornet (Vespa orientalis)
Naturwissenschaften |02/11/2010 |Marian Plotkin, Idan Hod, Arie Zaban, Stuart A. Boden, Darren M. Bagnall, Dmitry Galushko, David J.Bergman
Reference
“The complex structure of the cuticle is produced by extracellular secretion from the epidermis. It is constructed as a composite consisting of chitin filaments, structural proteins, lipids, catecholamine derivatives, and minerals. The Oriental hornet cuticle (the exoskeleton) exhibits a brown-yellow pattern…The yellow segments protect the cuticle from potentially harmful solar UV radiation, similar to the role of melanin in the brown color segments of the hornet’s body…The yellow segments contain xanthopterin, which is housed in an array of barrel-shaped granules…the voltage between the hypocuticle and the exocuticle of the yellow stripe showed a negative potential at the hypocuticle with respect to the positive exocuticle. In response to illumination of the yellow stripe, the difference in potentials between light and darkness increases…The fact that the Oriental hornet correlates its digging activity with insolation, coupled with the ability of its cuticular pigments to absorb part of the solar radiation, may suggest that some form of solar energy harvesting is performed in the cuticle.” (Plotkin et al. 2010:1068)
“[T]he epicuticle acts as an antireflective layer…the surface structure has evolved to confer both AR [anti-reflective] and light-trapping properties to the epicuticle, enhancing the absorption of light within the cuticle of the hornet, resulting in more efficient collection of solar energy.” (Plotkin et al. 2010:1073-4)
“[T]his underlying layered structure contributes to the overall reflectance properties of the epicuticle…Light passing through the yellow stripes is absorbed by xanthopterin, which serves as a light-harvesting molecule. The xanthopterin resides in tightly packed yellow pigment granules, which may serve to increase the effective surface area available for light absorption…allow absorption in the UV wavelengths while allowing an increase in the reflectance of higher wavelengths. The ability of xanthopterin to serve as a visible light absorber in a photo electrochemical solar cell is clearly evident from the I–V characteristics of the xanthopterin-sensitized solar cell…diffusion potential across the cuticle, with the inside negative with respect to the outside. Digby has suggested that electrons move through the semiconductive cuticular layer. This process creates calcium carbonate that precipitates in the cuticle…Oriental hornet has evolved a cuticle design to harvest solar energy…the surface structures confer AR and light-trapping properties, enhancing absorption by approximately 5% compared to a flat surface. The xanthopterin pigment found within the cuticle has been proven to be a suitable absorber of light for the harvesting of solar energy by a demonstration of its use in an organic solar cell, with a conversion efficiency of 0.335%.” (Plotkin et al. 2010:1075)
Journal article
Xanthopterin in the Oriental Hornet (Vespa orientalis ): Light Absorbance Is Increased with Maturation of Yellow PigmentGranules
Photochemistry and Photobiology |13/02/2009 |Marian Plotkin, Stanislav Volynchik, Natalya Y. Ermakov, Avishai Benyamini, Yulia Boiko, David J. Bergman, Jacob S.Ishay
Reference
“The findings clearly show that in regions of the hornet’s body where the cuticle is translucent, which in the Oriental hornet are the yellow stripes…there are ‘pockets’ engaged in enzyme activity and glucose analogous to the liver functions and enzymatic activity in other organs of mammals…As for the influence of illumination on this process, in all our tested hornets, the enzymatic activity was higher in the dark than in light…we have clearly ascertained that our hornet’s yellow stripes play a role in its metabolism. In short, the translucent, light-colored stripes comprise a very extensive tissue that actively participates in the metabolic processes of the hornet. This tissue somehow utilizes sunlight and promotes the production of enzymes and glucose and very possibly of other materials as well.” (Plotkin 2009 et al. :134)
Journal article
Some liver functions in the Oriental hornet (Vespa orientalis) are performed in its cuticle: Exposure to UV light influences these activities
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology |03/02/2009 |Marian Plotkin, Stanislav Volynchik, Dganit Itzhaky, Monica Lis, David J. Bergman, Jacob S.Ishay
Reference