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Why does human blood turn green in the deep ocean?
Why does human blood turn green in the deep ocean?
Human blood is red but in certain situations it can be green, for example in the deep ocean.
The reason is quite simple, you can use the physics knowledge learned in school to explain. According to the knowledge learned, any object we see is due to light reflecting from it and entering our eyes. Objects that absorb other light spectrums, reflecting red light will appear red.
But the reality is a little more complicated, objects typically reflect a range of wavelengths of light. Blood absorbs most colors and reflects light primarily in the red spectrum, with a much smaller amount of green and blue light.
The blood of a diver bitten by a Moray eel about 20 metres (65 feet) below the ocean surface was green.
Meanwhile, ocean water appears slightly blue because it absorbs a lot of light at red wavelengths. At a certain depth in the ocean, enough red light is absorbed that only the blue light is reflected back to our eyes, which then appears green. Therefore, human red blood appears green at ocean depths.
Because red light is absorbed very well by water, many species of fish appear red when living at the bottom of the ocean.
At the bottom of the ocean, red and black animals predominate. This is because black animals absorb all available colors of light, while red animals appear black because they have no red light to reflect and their bodies absorb all other available wavelengths of light.