Because vision is arguably our keenest and most important sense, it is easy to forget that there are many things our eyes cannot see. Polarised light and ultraviolet light are just two examples of the large variety of cues that are invisible to us, but are used by many animals, including small insects with tiny brains, to guide them in their everyday lives. I am interested in how the eyes of animals are specialised to see these cues, what information they can extract from them and how they are used in their behaviour.
My research career started in Germany, where I studied Biology, Physics and Computer Science between 1999 and 2003. Afterwards, I proceeded to the University of Cambridge (UK), where I obtained a Master's degree modelling visual sampling in the compound eyes of blowflies (Calliphora spp.). During my PhD at The Australian National University in Canberra, I studied the eyes and visual ecology of fiddler crabs (Uca vomeris) under the inspiring supervision of Jan Hemmi and Jochen Zeil. My research focussed on how different regions of the crabs' eyes are specialised for completely different tasks, how they see and use colours in their social life, and how the crabs' behaviour helps them to overcome the weaknesses and utilise the strengths of this particular eye design.
My current research at Lund University deals with the visual orientation and navigation behaviour in South African dung beetles (Scarabaeus spp.). Many of these beetles, after having found a source of fresh herbivore dung, form large balls and then quickly roll them away from the dung pile and the competition in a straight line. To keep their direction, they use cues from the sky such as the position of the sun or moon and the pattern of polarised skylight. But how do night-active beetles use these cues, when the light is a million times dimmer than during the day? What kind of eye specialisations are necessary to orient and navigate at night?
I am also interested in how these beetles overcome heat stress when rolling their balls on hot sand during the middle of the day. We have recently shown that Scarabaeus (Kheper) lamarcki solve this problem by using their dung ball as a mobile thermal refuge. When their front legs get too hot, they simply climb on top of their moist, and therefore cool, dung ball to cool down.
Another group of dung beetles (Pachysoma spp.) at the western coast of Africa has lost the ability to fly to the fresh, moist dung of large animals. Instead, they build a burrow and repeatedly forage for rodent dung or dried plant matter in the surrounding sand dunes. At each point of their foraging trip, they remember the exact direction and distance to their home. When they have found food, this allows them to return to their burrow in a straight line. How do they measure the direction and distance they have walked? And how do their eyes differ from those of their flying relatives?
My latest study deals with the unique galloping gait that three species of Pachysoma use while walking across the sands of Namaqualand.