A subcategory of “form following function” are the environment adaptations that breeds have developed and for which they’ve been bred. Let’s talk feet!
The feet of northern and arctic breeds have a unique adaptation that keeps their legs flexible and their feet from freezing even in temperatures of 60 degrees below zero (and an even lower when accounting for wind-chill factors). A circulatory system that has evolved and been selectively bred keeps the temperature of the foot pads of these breeds at just above the tissue-freezing point where the thick, tough pads come in contact with snow and ice. Warm blood coming from the heart and coming through the artery passes through capillaries called the “rete mirabile” where the warmth is passed to the veins carrying the cold blood from the feet back to the heart. In this way, the feet are fed by cooled blood, but the body and heart are spared the shock of warming that cold blood.
Is this not the coolest thing ever? (Ha, a pun!)
Greenland Dog by LA Shepard/thedoglover
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