Abstract

Fungi play essential roles in global ecology and economy, but their thermal biology is widely unknown. Mushrooms were previously noticed to be colder than surrounding air via evaporative cooling or evapotranspiration. Here we applied infrared imaging to reveal that not just mushrooms, but also molds and yeasts maintain colder temperatures than their surroundings via evapotranspiration. On average, fungal specimens are ~2.5 {degrees}C colder than the surrounding temperature. The relatively cold temperature of mushrooms can be observed throughout the whole fruiting process and at the level of mycelium. The mushrooms hymenium appeared the coldest and different areas of the Pleurotus ostreatus mushroom appear to dissipate heat differently. Evapotranspiration in yeast and mold biofilms can be measured from the accumulation of condensed water droplets above biofilms; which is significantly higher than the surrounding agar. We also present a mushroom-based air-cooling system (MycoCooler) capable of passively reducing the temperature of a closed compartment by approximately 10 {degrees}C in 25 minutes. These findings suggest that the fungal kingdom is characteristically cold. Since fungi make up ~2% of Earth biomass, their evapotranspiration may contribute to planetary temperatures in local environments. This study present new research avenues in fungal biology, biomedicine, microclimate, and sustainable energy.