An infrared image reveals “hot spots” on emperor penguins in Antarctica. (A.M. Thierry, A. Ancel /NATIONAL CENTER FOR SCIENTIFIC RESEARCH. PAUL EMILE VICTOR POLAR INSTITUTE)
Penguins keep warm in a cold coat

Emperor penguins are famous for their dapper outerwear, but that feather coat actually gets colder than the surrounding air, according to a study published in Biology Letters.

A team of Scottish and French scientists took hundreds of thermal images of emperor penguins at a breeding colony in Antarctica, creating a record of the birds’ body heat regulation in the harsh environment.

Average body surface temperatures dropped to as low as about 9 degrees below zero, which was about five degrees below the air temperature. The coat radiates more heat to the cold sky than it absorbs, the team reported, 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.