Emperor penguins (Aptenodytes forsteri) are famous for their dapper outerwear, but that feather coat actually gets colder than the surrounding frigid air, according to a study published online today in Biology Letters. A team of Scottish and French scientists took hundreds of thermal images (like the one above) of emperor penguins at a breeding colony in Antarctica. This provided a snapshot of the birds' body heat regulation in the harsh environment. On average, a penguin's body surface temperature dropped as low as -23°C, about 3° below air temperature. The coat radiates more heat to the cold sky than it absorbs from its surroundings, the team reports, causing the temperature to drop below that of the surrounding air, while thick insulation reduces body heat loss from the skin. Emperor penguins do have "hot spots": their eyes, flippers, and feet. But, special vessels circulate blood away from these surfaces to keep heat loss to a minimum.
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