Why Does Your Blood Appear Green In The Deep Ocean?

 

 What is the color of blood? 

If your answer is 'red', you're not incorrect, but you're not entirely right either.

 Blood color can change under certain conditions, like when you're deep underwater. 

In such a scenario, blood doesn't appear red anymore; instead, it takes on a mystifying green-blue hue.

 This phenomenon is intrinsically linked to why deep-sea creatures have evolved to sport red coloration.

The Green Color Mystery

Let's explore the root cause behind the blood's color transformation underwater.

 To understand this, one needs to recall the basic principles of light reflection and absorption, which we all studied in school.

When light reflects off an object and enters our eyes, we perceive the color of that object. 

Red objects absorb other light spectrums while reflecting red light, which is why they appear red to us.

Complexities of Light Reflection

However, reality is slightly more complex than this simplified explanation. 

Most objects reflect a range of light wavelengths.

 Blood, for instance, absorbs most colors and primarily reflects red light. 

However, it also reflects a smaller amount of green and blue light.

Water, on the other hand, has a blue appearance because it absorbs a significant amount of red light. 

As you descend deeper underwater, the absorption of red light increases to the point where only green light gets reflected back. Hence, your eyes perceive the blood as a green-blue color.

Fish Adaptation to Light Absorption

The high absorption rate of red light by water has led to a fascinating evolutionary adaptation in deep-sea fish. Most of these creatures are red in color.

According to the US National Oceanic and Atmospheric Administration (NOAA), these animals are invisible at depth. Red animals appear black because there's no red light to reflect, and their bodies absorb all other available wavelengths of light. 

Therefore, red and black animals are predominantly found in the deep ocean.

Color Perception Underwater

The color perception underwater is a captivating subject. 

Here's a demonstration of the green color we're talking about, as experienced by a scuba diver who had an encounter with a Moray eel at about 20 meters underwater.

Final Thoughts

Nature is full of surprises, and the phenomenon of blood appearing green in the deep ocean is one of them. 

The interplay of light absorption and reflection underwater results in this visual oddity, casting a new light on how we perceive color. 

The next time you think about the color of blood, remember that it's not always red!