Wings Reduce Heat Loss

a black and white penguin with white lines around its eyes flaps its wings surrounded by snow in the sunlight

Biological Strategy

Penguins

AskNature Team

Image: Markus De Nitto / Pixabay / Free non-commercial use

Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Birds

Class Aves (“bird”): Eagles, hawks, sparrows, parrots

Birds are evolutionary engineering marvels. They are descended from dinosaurs, but are far from our idea of heavy, scaly reptiles. Of the specific adaptions that set them apart, most notable is flight—although some mammals can fly, birds take the prize for abundance in the skies. Many birds have hollow, lightweight skeletons and specially-designed wings to help them stay aloft. They also have feathers made of keratin that help them stay warm, attract mates, and improve navigation and aerodynamics in flight. In contrast to their dinosaur ancestors, they lack true teeth and have replaced them with specialized beaks and bills.

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Wings of penguins reduce heat loss by forming a countercurrent heat exchanger via the vascular design.

“A major that allows penguins to forage in cold water is the humeral arterial plexus, a vascular counter-current heat exchanger (CCHE) through the flipper…Foraging exposes penguins to water well below core body temperature and presents a constant threat of hypothermia, a risk avoided in part by managing the flow of heat along the wing. [In most birds] Blood is supplied to the wings of birds through a single major vessel that traverses the humerus as the brachial artery…By contrast, the brachial artery of penguins splits into three to five major vessels that traverse the humerus before anastomosing to two arteries at the humerus–radius joint. Each humeral artery is associated with two or more veins to form a countercurrent heat exchanger (CCHE), the humeral arterial plexus. Blood is supplied to the wing at core body temperature (38.5 deg C), and outgoing arterial blood heats the cooler incoming venous blood at the plexus; heat is thus conserved and returned to the body core instead of travelling further out along the wing to become lost to cold water. The efficacy of the humeral plexus as a CCHE mechanism has been demonstrated by up to 30 deg C internal temperature differences measured between the shoulders and wingtips of penguins.” (Thomas et al. 2011:461)