Penguins Are Controlling
Here is the miracle: penguins can control their rate of their blood flow. How? They do it by nature, and their bodies vary the diameter of their arterial blood vessels in a phenomenon called Rete Mirabile—a Latin word meaning “wonderful net." A network of blood vessels, that is.
Under cold conditions, the flow of fluid is reduced and when warmer, the blood flow increases. This system is called countercurrent heat exchange. The arteries in their legs lead down to many much smaller vessels. Too warm? The skin and arteries dilate or become wider, bringing heat from within the body to the surface to be burned off as energy. Another group of venous vessels can bring the cold blood up from the source, such as their feet, to be warmed! Humans do this too in a modified version when their hands are white cold and turn pink when they are warm.
King and emperor penguins are able to tip up their feet too, and rest their entire weight on a tripod of the heels and tail, reducing contact with the icy surface and so reducing heat loss.
Penguin feet are actually a degree or two above freezing to the minimize heat loss and prevent frostbite.
King penguins also have mitochondrial functioning in their cells that allow them to produce heat to survive the cold without depleting their energy stores. Their body furnace is regulated to last!