Animals and Optics - Seeing the world in a different light

12 February 2018, 5.00 PM - 12 February 2018, 6.00 PM

Professor Nicholas Roberts (Ecology of Vision Group, School of Biological Sciences, Bristol)

Berry lecture theatre (3.21)

Over the last 500 million years, the processes of natural and sexual selection have given rise to many remarkable visual and optical systems in animals [1]. From single photon sensitivity to structural colour, or twelve-channel colour vision to achromatic retardation devices, the exploitation of several fundamental optical principles can be understood in the context of optimisation and the direct fitness and ecological benefits. However, such optimisation is under considerable constraint and the central theme of this talk is how animals have evolved to overcome some of these constraints by using novel optical mechanisms.

In this talk I will focus on two different areas and some recent work from the Ecology of Vision Group in the School of Biological Sciences. Animals are constrained to only being able to use a limited number of organic materials for structural reflectors: commonly chitin, guanine or the protein reflectin. To improve angular performance and increase levels of reflectivity whilst maintaining a minimal thickness structure, animals have evolved architectures that exploit the anisotropic optical properties of birefringence [2, 3, 4] and orientational order [5].

Furthermore, being able to increase the detection and use of visual information without an increase in energy budget also provides an advantage. Animals make effective use of matched filter designs [6], dynamic contrast enhancement using the polarization of light [7] and directional retinal specialisations to overcome these constraints. And in an era of sophisticated modern visual technologies, we still have much to learn from these natural systems with regard to such optimisation and dynamic performance.

References

[1]  Innes C Cuthill, William L Allen, Kevin Arbuckle, Barbara Caspers, George Chaplin, Mark E Hauber, Geoffrey E Hill, Nina G Jablonski, Chris D Jiggins, Almut Kelber, Johanna Mappes, Justin Marshall, Richard Merril, Daniel Osorio, Richard Prum, Nicholas W Roberts, Alexandre Roulin, Hannah M Rowland, Thomas N Sherratt, John Skelhorn, Michael P. Speed, Martin Steven, Mary Caswell Stoddard, Devi Stuart-Fox, Laszlo Talas, Elizabeth Tibbetts, and Tim Caro. The biology of color. Science, 357(6350):eaan0221, 2017. 


[2]  TM Jordan, JC Partridge, and NW Roberts. Non-polarizing broadband multilayer reflectors in fish. Nature Photonics, 6(11):759–763, 2012. 


[3]  TM Jordan, JC Partridge, and NW Roberts. Disordered animal multilayer reflectors and the localization of light. Journal of The Royal Society Interface, 11(101):20140948, 2014. 


[4]  Kathryn D Feller, Thomas M Jordan, David Wilby, and Nicholas W Roberts. Selection of the intrinsic polarization properties of animal optical materials creates enhanced structural reflectivity and camouflage. Philosophical Transactions of the Royal Society B, 372(1724):20160336, 2017. 


[5]  Thomas M Jordan, David Wilby, Tsyr-Huei Chiou, Kathryn D Feller, Roy L Caldwell, Thomas W Cronin, and Nicholas W Roberts. A shape-anisotropic reflective polarizer in a stomatopod crustacean. Scientific Reports, 6:21744, 2016. 


[6]  Martin J How, Megan L Porter, Andrew N Radford, Kathryn D Feller, Shelby E Temple, Roy L Caldwell, N Justin Marshall, Thomas W Cronin, and Nicholas W Roberts. Out of the blue: the evolution of horizontally polarized signals in Haptosquilla (Crustacea, Stomatopoda, Protosquillidae). Journal of Experimental Biology, 217(19):3425–3431, 2014. 


[7]  Ilse M Daly, Martin J How, Julian C Partridge, Shelby E Temple, N Justin Marshall, Thomas W Cronin, and Nicholas W Roberts. Dynamic polarization vision in mantis shrimps. Nature Communications, 7:12140, 2016. 


Contact information

For further information, contact Molly Hackett at molly.hackett@bristol.ac.uk

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