Daily Devotional – October 29

Biology

On a cold winter day, you may notice a duck walking on ice and another walking in snow. How is it possible that their feet don’t freeze and fall off - given their bare legs and feet? Like many birds, ducks have a unique warming system called a “countercurrent” heat exchanger inside their legs and feet.

Engineers have long understood that when two pipes are touching each other with the fluid flowing in the same direction, half the heat is transferred to the other pipe’s fluid. If, however, the two fluids move in opposite directions, nearly 100% of the heat can move from the warmer pipe to the colder pipe. That is what happens in ducks! The pipe (artery) carrying warm blood runs down to the feet and passes next to the pipe (vein) with the cold blood coming from the feet. When the exchange takes place the heated blood transfers about 95% of its heat before it reaches the feet. In engineering design, this is called a counter current heat exchanger. Combine this with the legs and feet made mostly of bones/ hard parts, and you get feet that neither freeze nor waste heat energy. God in His wisdom created the counter current heat exchanger long before engineers discovered the principle.

The next time you see a duck or bird standing in snow, tell your friend why birds do not have to wear winter boots. God built into these creatures a counter current heat exchanger!

If any of you lack wisdom, let him ask of God, that giveth to all men liberally, and upbraideth not; and it shall be given him.

~ James 1:5

Source: "Pearls in Paradise" by authors Bruce Malone and Jule Von Vett

References for this devotional.