Dr Nicholas Roberts
"At every step and every scale you have to appreciate that the world is not always as we see it. I’ve always been fascinated with how other animals see their world and whether we can understand how it appears to them?"
Dr Nicholas Roberts is part of Bristol University’s world-renowned Ecology of Vision Group, investigating the optics of different visual and signalling systems in a variety of animals.
Having originally started out in physics, Nick’s approach combines physical techniques such as laser tweezing, holographic microscopy, optical modelling and imaging microspectrophotometry, with behavioural studies, phylogenetics and fieldwork.
He joined Bristol University in 2009 as a BBSRC David Phillips Research Fellow before taking up a permanent position in 2012. A recent focus of the labs work has been studying animals called stomatopods, a crustacean commonly called a mantis shrimp.
Stomatopods have the most complex visual system we currently know about in any animal. Humans see colour by using three different types of light sensitive cells in our eyes; cells that are sensitive to red, green or blue. However, stomatopods use upwards of 12 different types of cell to give them a very different sense of colour compared from ours.
In fact many animals see colour very differently from us, some using four or five colour channels, particularly with sensitivity to ultraviolet light. In our lab we are interested in how stomatopods are able to process such large amounts of information - stomatopods have not only such a large number of colour channels but also three different parts to each eye, which process information differently.
Another focus of the lab is understanding how different animals see the polarization of light. Polarization is a property of light that tells us about how light is travelling. Light travels as a wave, oscillating as it moves through space. As it travels, a single wave could oscillate up and down, side to side or any angle in between. The angle of polarization just refers to orientation of a wave is oscillating in.
Typically, as light is reflected from different surfaces, be it water or a wet road, the reflected light becomes horizontally polarized. As humans we’ve learnt ways to cut out such reflections, for example fisherman wear Polaroid sunglasses. However many animals have adaptations within their eyes to not only improve contrast by cutting out polarized reflections in the same way, but use the angle of polarization as an artificial horizon, or the polarization patterns in the sky as a compass for navigation.
Something I realised very early on in my PhD was that I didn’t want to just work in a windowless optics lab.> For my PhD I studied how light propagates through new types of liquid crystal display and was interested in calculating how different liquid crystal phases manipulated the flow and properties of light.
How light interacts with different organic systems, out of which we make displays, isn’t actually any different from how light interacts with the light sensitive cells in our visual system. And that’s how my cross-over from pure optics to biology started. However, it works both ways.
Several discoveries we’ve made in recent years have become a source of biomimetic inspiration for man-made optical technologies. Natural selection is the process that supports these remarkable adaptations, a process that has resulted in many more elegant solutions than those that humans have engineered.
For example, in the case of stomatopods, we discovered a cell type in their eyes can change the angle of polarization of light far better than any man-made device designed to do the same job. Currently we use those devices in every CD or DVD player, but now other researchers have started copying the stomatopod’s optics and are trying to manufacture devices based on the cells in stomatopod eyes.
Whether you’re studying behavioural ecology, sensory or even molecular biology, at every step and every scale you have to appreciate that the world is not always as we see it. As humans, we tend project an anthropocentric viewpoint, trying to explain discoveries in terms of our experience and language – and often that’s not right.
We always have to remember that natural or sexual selection occurs in the context of the animal’s sensory abilities. Many animals are very good at camouflaging themselves, but some, for example, cuttlefish or octopus, can change their camouflage depending on the background. What is remarkable is that the animals themselves, are colour blind.
Currently, several multi-university research programs are studying the links between the information required to match a background pattern and the physiology these cephalopods have with which they do it so well.
A key theme that is common to visual ecology, and many forms of sensory biology is the subject’s multi-disciplinary and cross-disciplinary nature. You can’t look at an animal’s visual ecology without understanding physics and optics, physiology, behavioural biology and evolution.
Being granted a research fellowship is one of the most fantastic opportunities you can be given. Fellowships provide you with the freedom and flexibility to concentrate on research. Discoveries are not always planned; serendipity often plays a role.
However, it is always important that we maximise the impact of our science, and that those discoveries, planned or otherwise, are readily available to be used to benefit other areas of science and technology.
- Non-polarizing broadband multilayer reflectors in fish
Nature Photonics, 2012
- Silvery fish fool predators with their skin
- Hiding in the Light
American Physical Society podcast, 2012
- A biological quarter-wave retarder with excellent achromaticity in the visible wavelength region
Nature Photonics, 2009
- Shrimp eyes could lead to new generation of DVD players
The Telegraph, 2009