You must have seen the transparent fish, which is one of the extraordinary natural beauties we come across on social media many times. The most striking feature of these enormous creatures, whose scientific name is ‘Kryptopterus vitreolus’, is that they are transparent.
Because they are transparent, they can even reflect rainbow colors, which are sometimes caused by color refraction. Of course, people don’t think, these creatures are transparent, okay.
So how can these fish shine like a rainbow?
Qibin Zhao, a physicist at Shanghai Jiao Tong University in China, was also curious about this question and began to research this creature. Ghost catfish allow 90% of the light to pass directly through their body. It also has no scales and its skin is about 20 micrometers thin.
But that doesn’t explain why the fish reflect the colors of the rainbow. To explain this, the researchers dissected the fish by separating the skin from the back and abdominal muscles.
The researchers shined a white laser on the skin of the fish, and this beam passed directly through the skin. However, the same was not the case for the muscles. Something in them was causing the light waves to fluctuate in a way known as diffraction, creating a rainbow effect.
Each muscle is made up of elastic units called sarcomeres. Using electron scanning microscopes and optical microscopes, the researchers discovered that these fibrous units act as diffraction gratings and split the light beam into a rainbow as it passes through the structure.
The directions of the fish as they move create varying angles where the light hits the muscles, causing the colors refracted from the muscles to appear like rainbows.
The researchers point out that other fish have the same muscle type, but because their skin is not transparent, the shine cannot be seen from the outside. And as researchers have already explained, these creatures are not completely transparent.
The team speculates that the species Kryptopterus vitreolus glows in color because it evolved to distract predators and survive. Another possibility is that the fish use it as some kind of communication system. Because these fish are very social species that live in communes.
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