How Is The Red Blood Cell Adapted To Its Function?

It's function is primarily oxygen transport.  Intracellular proteins called hemoglobin are the primary agents that bond Oxygen within RBC's.  The RBC loses it's nucleus as it matures and therefore has room for the maximum amount of hemoglobin.  Also it is discoid in shape for greater surface area which helps with gas exchange and it can contort and squeeze through small capillaries to deliver it's supply of Oxygen to the tissues supplied by those capillaries.