How the eye evolved might be explained after a cell grew its own eye

21 Jul 2015

Transmission electron micrograph showing the eye-like structure in the warnowiid. Image via University of Columbia

Scientists are getting rather excited after one single-cell organism ‘caught the eye’ of their gaze as it appeared to show that it grew a basic eyeball that could answer questions about how our own eyes are formed.

How the eye evolved has always been one of the trickiest questions in evolutionary biology with only a few theories as to how we came to see everything around us, but now a team of marine biologists stumbled across one rather peculiar organism that had its own concept of sight and have published their findings in Nature.

While looking in a sample of seawater, the team from the University of British Columbia found something looking right back at it, with the single-cell organism shown to have many similar characteristics to our own eyes, including a lens, cornea and retina.

According to Cosmos, the organism is known as a warnowiid and is usually found off the coast of Canada and Japan in minute numbers and is incredibly elusive from a research perspective given that it disintegrates immediately after being taken from the water.

To catch a glimpse of this sample, Greg Gavelis and his team had to freeze a warnowiid sample under a microscope for a year after trapping it in a plastic resin and, using 3d modelling, saw the incredible eye feature.

How the eye evolved diagram

An illustration of the warnowiid eye. Image via University of Columbia

Evolved eye to hunt

The findings show that rather than using a basic dark/bright detection system like most organisms, the warnowiid appears to have used its internal organelles and repurposed them to form the three basic components of a functioning eye.

The research team believes that this evolutionary change occurred at some point when a warnowiid consumed algae and then adopted its photosynthetic capabilities, only to switch again to an eye, allowing it to hunt.

The exact function of the eye, however, is still unknown with it believed to not function exactly like our own eyes, but rather one that concentrates levels of light to indicate where prey is.

Speaking of the remaining critics of the theory of evolution, Gavelis said: “Critics of evolution often talk about how there are no transitional forms of eyes. But they’re alive and well in this case.”

Colm Gorey was a senior journalist with Silicon Republic