Written by Michael Botes
Gravity is a giraffe’s biggest enemy. It doesn’t help when they have to bring their head completely down to be able to drink water or to feed on lower shrubs – surely all the blood rushes to their head?
So the big question is: How does a giraffe’s heart pump a sufficient amount blood up such a long neck, and prevent it from rushing to its head when it bends down to drink?
The answer lies in the structure of its heart, which is large and significantly heavier than other mammals. The walls of the left ventricle are up to 7cm thick, beating at almost three beats per second at great pressure.
This allows the blood to be pumped through the large body against the force of gravity and the pressure of blood contained in the arteries on the way to the brain. A selection of valves prevent any damage to the organs – especially for the brain – when the head is lowered.
The skin around the legs are also incredibly thick and tight, like how a compression sock maintains pressure and forces the blood to pump back up against gravity. Interestingly even the anti-g suits that pilot’s wear were designed around this principle.