![Blue blood](https://assets.shortpedia.com/uploads/2022/09/13/1663057546.webp?tr=w-1200,h-600,cm-pad_resize,bg-F3F3F3)
Spiders, unlike humans, have blue blood. However, there is a scientific explanation for this. In humans, oxygen is bound to an iron-containing molecule, which gives our blood its red colour. However, in spiders, the molecule to which oxygen is bound contains copper, giving their blood a blue colour.