Beneath the icy waters of Antarctica, penguins have a clever secret for survival. It starts in their legs.
Their legs serve as heat exchangers, recycling warmth before it dissipates into the cold.
As blood flows down to their feet, it loses heat but not all of it; veins and arteries are positioned closely together.
This arrangement allows warmer blood to warm the cooler blood returning from the feet, maintaining a core temperature.
By keeping their feet just above freezing, around 0°C, they avoid frostbite and can stand on ice for hours.