Did you know that the blood of different animals can be different colours. The different colours are caused by pigments and proteins found in the blood, which help the animals survive in different conditions.
Animals like the large Antarctic octopus, living in very cold water, have light blue blood. They have lots of haemocyanin, a copper based protein which is blue. The haemocyanin helps the blood to take in oxygen at low temperatures. Spider blood is also pale blue. Spiders use blood pressure to get shed their old skin as they grow.
Some animals, like the peanut worm have purple blood! The protein hemerythrin, which transports the oxygen, is colourless until it combines with oxygen and then it turns purple. The protein also helps worms regenerate parts of their bodies if they get cut off.
Also there are animals with green blood – these are usually lizards and worm like animals. A pigment called biliverdin makes the blood green. It can also turn your skin green if you are wounded!
GCSE biologists, if you need help with understanding the blood, and blood vessels, try our new guide “How to work with the Circulatory System: Part 2”. It includes a description of the main parts of the blood, their functions, and the difference between arteries, veins and capillaries. There are questions and answers included.
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