The blood may be colourless, or have any of three different respiratory pigments. The most common of these is haemoglobin, but some groups have haemerythrin or the green-coloured chlorocruorin, instead.
The blood may be colourless, or have any of three different respiratory. pigments. The most common of these is haemoglobin, but some groups have haemerythrin or the green-coloured chlorocruorin, instead