Cyanobacteria can sense and focus light. Scientists have known for over 300 years that bacteria can sense light. ¬†Bacterial photoaxis, how bacteria move toward light, wasn’t properly understood because of their microscopic size.

Researchers, from Queen Mary University of London, have discovered how the bacteria sense light and move toward it. The entire bacteria cell acts like an eyeball. The light rays hitting the cell are bent and focused on the opposite cell wall using the same principle as the human eye. The high intensity light on the back wall causes the bacteria to move away from the focused light and toward the natural light.

This makes the bacteria “probably the world’s smallest and oldest example” of a light focusing lens, researchers write in the journal eLife.

Cyanobacteria have been around for over 2.5 billion years and are found everywhere; for example, blue green algae. These tiny organisms are essential for the oxygen in the atmosphere and likely transformed earth’s atmosphere during the “Great Oxidation Event”. Around 2.5 billion years ago, earth’s atmosphere rapidly gained oxygen thanks to cyanobacteria.

These bacteria provide valuable insight into the evolution of our eyes.

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