Counter current heat exchange in penguin wingYour model is disabled. For more details go to Edit properties3D Model
Penguins are warm-blooded animals that forage in water that is much cooler than their body temperature. A counter current exchange mechanism in the wing helps penguins to avoid hypothermia. Shown here are the major arteries (red) and veins (blue) along the wing bones from a little penguin (Eudyptula minor) that establish this counter current exchange mechanism.
Warm arterial blood flows from the heart and along the arteries towards the wingtip. Venous blood returning from the wingtip has lost much of this heat is is relatively cold. The warm arteries and cold veins run alongside one another against the humerus, the upper-most bone in the wing. Heat from the arteries is transferred to the veins. This heat is then returned to the body core instead of being carried out to the wingtip and lost to the ocean.
This model is based on Figure 1 from: Thomas DB & Fordyce RE. 2007. The heterothermic loophole exploited by penguins. Australian Journal of Zoology 55: 317–321.