Congratulations and well done to our new SRH Scientist of the Week for correctly answering the question – “Why don’t penguins’ feet freeze?”
The answer to the question actually has two
parts; firstly, the penguin can control the rate of blood flow to the feet by
varying the diameter of arterial vessels supplying the blood. This reduction of blood flow near the skin
surface prevents loss of body heat to the outside. Humans can do this too, which is why our hands and feet
become white when we are cold and pink when warm. Secondly, penguins make use of a system known as the
counter-current heat exchange. This
important adaptation ensures that the heat from the descending blood is
transferred directly to the cold returning blood, bypassing the feet all
together. Not only does this maintain the core body temperature but by
limiting how much heat gets sent to the feet the penguins can reduce the amount
that’s lost to the outside air keeping their cells above freezing to avoid
frostbite.
This week’s question is “Do pigeons sweat?”
