One of the oldest organisms on earth, Cyanobacteria or pond scum, use their entire bodies as eyes to detect light. The tiny blue-green bacteria appeared about 2.7 billion years and became one of the first creatures to depend photosynthesis (converting light from the sun into energy or “food”) for fuel. Scientists knew that the bacteria had a way to sense the light and even to move toward it, called “phototaxis,” but until now they didn’t know that entire bacteria actually acts as eyeball.

The researchers added a gene to the bacteria that caused them to produce a fluorescent dye in a layer of their bodies that encases their cell membrane called the periplasm. They then shined a light at the bacteria and observed that they light was being bent (or refracted) as it passed through the cell, and appeared as glowing areas on the opposite side of the bacteria. This is similar to how the lenses in human eyes bend and focus light onto our retinas, only cyanobacteria focus light on the opposite side of the cell from the light source. The bacteria are 500 times smaller than a human eye, and therefore can probably only see blurry outlines and shapes. However, according to the scientists, their vision would be good enough to see the shape of a human standing over them. Pretty cool huh?!

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Feb 15, 2016