Cyanobacteria use their whole bodies as eyeballs

Round single cells may have been the first creatures to see Earth

HEY LOOK The spherical bacteria Synechocystis (shown here in false color) can use their single-celled bodies almost like eyeballs. A light shining up from the bottom of this image passes through the cells and focuses on the far side (white arrows highlight examples of focused light). A laser light source in the center (red dot) helped test which way the cells move in reaction to bright spots of light.

N. Schuergers et al/eLife 2016

By Susan Milius

February 9, 2016 at 7:40 pm

After all those years of people looking into microscopes at bacteria, it turns out that some of the bacteria are (sort of) looking back.

Synechocystis bacteria focus light in a roughly eyeball-like process, says Conrad Mullineaux of Queen Mary University of London. Light shining through their spherical cells focuses on the opposite side, where light-sensitive substances react, he and colleagues report February 9 in eLife.

Biologists knew cyanobacteria move toward light, but this method of detecting it was a surprise. Human vision differentiates between two points about 1,000 times better than do the cyanobacteria, but Mullineaux calculates that the bacterial resolution should be enough for Synechocystis to pick out the outline of his head and shoulders bending over them.