Abstract
The Saharan silver ant Cataglyphis bombycina is one of the terrestrial living organisms best adapted to tolerate high temperatures. It has recently been shown that the hairs covering the ant’s dorsal body part are responsible for its silvery appearance. The hairs have a triangular cross-section with two corrugated surfaces allowing a high optical reflection in the visible and near-infrared (NIR) range of the spectrum while maximizing heat emissivity in the mid-infrared (MIR). Those two effects account for remarkable thermoregulatory properties, enabling the ant to maintain a lower thermal steady state and to cope with the high temperature of its natural habitat. In this paper, we further investigate how geometrical optical and high reflection properties account for the bright silver color of C. bombycina. Using optical ray-tracing models and attenuated total reflection (ATR) experiments, we show that, for a large range of incidence angles, total internal reflection (TIR) conditions are satisfied on the basal face of each hair for light entering and exiting through its upper faces. The reflection properties of the hairs are further enhanced by the presence of the corrugated surface, giving them an almost total specular reflectance for most incidence angles. We also show that hairs provide an almost 10-fold increase in light reflection, and we confirm experimentally that they are responsible for a lower internal body temperature under incident sunlight. Overall, this study improves our understanding of the optical mechanisms responsible for the silver color of C. bombycina and the remarkable thermoregulatory properties of the hair coat covering the ant’s body.
Highlights
Cataglyphis bombycina, the”silver ant” of the Sahara, the Sinai and the deserts of the Arabian Peninsula, is famous for its ability to withstand extremely high temperatures [1,2]
Using theoretical and empirical approaches, we demonstrate that the bright silver color of the ant C. bombycina stems from the total internal reflection (TIR) associated with the hairs that densely cover the ant body
scanning electron microscopy (SEM) analyses confirm that the hairs covering the cuticle assume a triangular cross-section (Fig 2a)
Summary
Cataglyphis bombycina, the”silver ant” of the Sahara, the Sinai and the deserts of the Arabian Peninsula, is famous for its ability to withstand extremely high temperatures [1,2]. Workers come out from the nest during the hottest midday period, when temperatures exceed 50°C, to scavenge corpses of heat-stricken animals. By restricting foraging activity to the hottest period of the day, the ants minimize the chances of encountering their most frequent predator—a. Total Internal Reflection in Saharan Desert Ants no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
