May 8, 2025
Not all blood is red! In the animal kingdom, blood can be blue, green, purple, and even clear, thanks to different proteins and elements. Here are 10 such fascinating creatures.
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Horseshoe crabs have blue blood due to hemocyanin, which contains copper instead of iron. Their blood is crucial in medical testing for bacterial contamination.
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An octopus also has blue blood, thanks to hemocyanin, which helps them survive low-oxygen environments in the deep sea.
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Found in Antarctic waters, icefish have clear blood, they lack hemoglobin entirely, surviving with oxygen dissolved directly in their plasma.
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Some species of leeches have green blood, caused by a different pigment known as chlorocruorin, which works similarly to hemoglobin.
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These deep-sea creatures also have green blood, with high levels of vanadium and other unusual elements in their circulatory systems.
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Some peanut worms have purple blood, due to a molecule called hemerythrin that turns violet when oxygenated.
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Brachiopods, marine animals resembling clams, also possess purple blood thanks to hemerythrin, which transports oxygen efficiently in cold water.
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Most spiders have blue blood, like octopuses and horseshoe crabs, because of the presence of hemocyanin.
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Scorpions share the same trait, blue blood rich in copper-based hemocyanin, ideal for desert survival where oxygen is scarce.
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Some tunicates have green or yellowish blood containing vanadium compounds, which are still a mystery to scientists.
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