Keeping cool: Enhanced optical reflection and radiative heat dissipation in Saharan silver ants

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Science  17 Jul 2015:
Vol. 349, Issue 6245, pp. 298-301
DOI: 10.1126/science.aab3564

Keeping cool

Silver ants inhabit one of the hottest and driest environments on Earth, the Saharan sands, where most insects shrivel and die moments after contact. Shi et al. show that the triangular shape of the silver hairs that cover their bodies enables this existence. The hairs both increase the reflection of near-infrared rays and dissipate heat from the ants' bodies, even under full sun conditions. Evolution's simple solution to intense heat management in this species could lead to better designs for passive cooling of human-produced objects.

Science, this issue p. 298


Saharan silver ants, Cataglyphis bombycina, forage under extreme temperature conditions in the African desert. We show that the ants’ conspicuous silvery appearance is created by a dense array of triangular hairs with two thermoregulatory effects. They enhance not only the reflectivity of the ant’s body surface in the visible and near-infrared range of the spectrum, where solar radiation culminates, but also the emissivity of the ant in the mid-infrared. The latter effect enables the animals to efficiently dissipate heat back to the surroundings via blackbody radiation under full daylight conditions. This biological solution for a thermoregulatory problem may lead to the development of biomimetic coatings for passive radiative cooling of objects.

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