Short-beaked echidnas cannot pant, sweat, or lick themselves for cooling. Thermal imaging of wild animals revealed another route: they blow mucus bubbles that burst over the tip of the beak. As that moisture evaporates, the richly supplied nose loses heat and cools the blood beneath it. Researchers call the wet nose tip an evaporative window. The bubble is not a cold symptom. It is tiny built-in air conditioning.