The strikingly beautiful Saharan silver ant is capable of withstanding some of the most extreme temperatures on the planet. New research shows that their silver sheen serves as a heat-repellent system, reflecting incoming sunlight like a prism. Scientists call it "total internal reflection", and it's what gives these ants their unique appearance. The ants have glittery hairs that feature a triangular cross section — much like a prism — with a pair of grooved surfaces that divert incoming visible and near-infrared light. This enables the desert ant to maintain a lower body temperature, allowing it to cope with temperatures that exceed 50C. So the ants can forage during the day, a time when other animals, including some of their predators, would rather avoid the heat.
A research team from the Free University of Brussels studied these hairs under an electron microscope to trace the path of incoming light rays. They also compared normal "hairy" silver ants with a sample of silver ants that had their hairs removed (the researchers used a tiny scalpel to shave the ants, which must've been incredibly tedious).
Electron microscopy of silver ant hair. Image: Quentin Willot et al., 2016/PLOS One
The results, published in PLOS One, showed that the normal, unshaven ants were able to stay up to 2C when exposed to simulated sunlight. Led by Serge Aron, the team also showed that the hairs provide an almost 10-fold increase in light reflection, allowing for a lower internal body temperature.
The triangular cross-section, along with the grooved surface of each hair, causes light to undergo total internal reflection. The light bounces off the back of the bottom plane of the hair instead of going right through it. This mirror effect not only gives these ants their silvery sheen — it reduces heat absorption from sunlight.
Top: The Saharan silver ant. Image: Quentin Willot et al., 2016/PLOS One