Human Anatomy, Physiology, and Medicine. Anything human! It is
quite interesting to look for the right answer about whether
blood can be blue or not on the Internet. It seems everyone has
the 'facts' to back there claim up. Technically you could also
say that blood is clear if it has just white blood cells and no
red blood cells. Regina - working in the lab I don't understand
how this topic can keep going and going. Quite clearly, if you
take a venous blood sample into an evacuated tube you can see
the blood is dark red. If you use the same method to draw an
arterial blood sample the blood is bright red. And yes, the
blood is colourless if you remove erythrocytes, but I doubt we
can call it blood anymore then. Blood is blue if you have
haemocyanin instead of haemoglobin, but that require you to be a
horseshoe crab or similar, which utilizes copper instead of iron
to carry oxygen. And I do not think we are talking about marine
arthropods here... Possibly because blood gets darker as it
congeals? But what about