A joint project conducted by Columbia University, The University of Washington and the University of Zürich indicates how Saharan Silver Ants stay cool in one of the hottest climates in the world. The team’s research paper titled ‘Saharan Silver Ants Keep Cool by Combining Enhanced Optical Reflection and Radiative Heat Dissipation’ was recently published in Science Magazine.
During experimentation, the research group discovered the Saharan ants rely on the hair on their coats to stay cool; the hair controls ranges of electromagnetic waves. The team also discovered infrared light is important in assisting the ants in staying cool.
“Yu and his team used electron microscopy and realized that the ants’ bodies are coated with hairs containing triangular cross-sections. These hairs are responsible for cooling the animals in two ways. First, they’re highly reflective under both visible and near-infrared light (the maximum solar radiation region). The hairs also happen to be highly emissive in the electromagnetic spectrum’s mid-infrared region. They act as an antireflection layer that helps the ant offload excess heat by way of thermal radiation. The passive cooling effect works under the full sun whenever the insects are exposed to the clear sky,” according to Engineering.com.
Saharan Silver Ants function midday to avoid most predators; however, midday temperatures can reach 158 degrees Fahrenheit. The ants keep their body temperatures below 128.5 degrees Fahrenheit in order to survive.
The group determined the ant’s cooling technique helps reduce its body temperature by up to 10 degrees.
“The fact that these silver ants can manipulate electromagnetic waves over such a broad range of spectrum shows us just how complex the function of these seemingly simple biological organs of an insect can be,” Nan Shi, a Ph.D. student who works with Yu, said.
“This is a telling example of how evolution has triggered the adaptation of physical attributes to accomplish a physiological task and ensure survival, in this case to prevent Saharan silver ants from getting overheated. While there have been many studies of the physical optics of living systems in the ultraviolet and visible range of the spectrum, our understanding of the role of infrared light in their lives is much less advanced. Our study shows that light invisible to the human eye does not necessarily mean that it does not play a crucial role for living organisms,” Nafgang Yu, an assistant applied physics professor at Columbia Engineering, said.
This discovery could lead to development of optical components with excellent cooling properties, according to Engineering.com.
“Such biologically inspired cooling surfaces will have high reflectivity in the solar spectrum and high radiative efficiency in the thermal radiation spectrum. So this may generate useful applications such as a cooling surface for vehicles, buildings, instruments, and even clothing,” Yu added.
The team’s next steps are to study other animals and determine how other species stay cool in extreme temperatures.
