Watch out! Bacteria can see like human beings

It has taken scientists over 300 years to finally figure out how bacteria "see" their world, and they do it in a remarkably similar way to us.

The team of British and German researchers revealed how bacterial cells act as the equivalent of a microscopic eyeball or the world's oldest and smallest camera eye.

"The idea that bacteria can see their world in basically the same way that we do is pretty exciting," says lead researcher Conrad Mullineaux, professor of microbiology from Queen Mary University of London (QMUL).

Cyanobacteria are found in huge numbers in water bodies or can form a slippery green film on rocks and pebbles.

Synechocystis - the species used in the study - is found naturally in freshwater lakes and rivers.

Cyanobacteria evolved around 2.7 billion years ago and the fact that they are able to produce oxygen and fix carbon dioxide using energy from the sun (photosynthesis) is thought to have caused mass extinctions and the oldest known ice age.

The current study reveals that they are able to do this because the cell body acts like a lens.

As light hits the spherical surface, it refracts into a point on the other side of the cell. This triggers movement by the cell away from the focused spot.

Within minutes, the bacteria grow tiny tentacle-like structures called pili that reach out towards the light source.

As they attach to the surface that they're on, they retract and pull the bacteria along.

The findings are most likely an example of convergent evolution between bacteria and more complex multi-cellular organisms including animals and humans.

"The physical principles for the sensing of light by bacteria and the far more complex vision in animals are similar but the biological structures are different," noted co-author Annegret Wilde from the University of Freiburg in Germany in a paper that appeared in the journal eLife.

A Synechocystis cell is about half a billion times smaller than the human eye.

"No one else noticed it before despite the fact that scientists have been looking at bacteria under microscopes for the last 340 years," Mullineaux pointed out.