Single-Celled Organism Evolves Eye-Like Feature

Posted on July 6, 2015

Scientists have discovered that a single-celled marine plankton, called warnowiids, have evolved an eye-like feature. The eye or "ocelloid" could be used by the warnowiids to better see its prey. When this feature was first discovered it was originally thought to be the eye of a creature eaten by the warnowiids. A transmission electron micrograph showing the eye-like structure in warnowiid dinoflagellates is pictured above.

The warnowiid eye has features that are found in the eyes of more complex creatures, such as a cornea and retina. The warnowiids use harpoon-like structures when they hunt transparent prey cells in the plankton. The researchers speculate that the eye may help warnowiids detect shifts in light as it passes through their transparent prey.

Greg Gavelis, a zoology PhD student at University of British Columbia (UBC) and lead author of the study, says in a statement, "It's an amazingly complex structure for a single-celled organism to have evolved. It contains a collection of sub-cellular organelles that look very much like the lens, cornea, iris and retina of multicellular eyes found in humans and other larger animals."

UBC zoologist Brian Leander, senior author on the paper, says in a statement, "The internal organization of the retinal component of the ocelloid is reminiscent of the polarizing filters on the lenses of cameras and sunglasses. It has hundreds of closely packed membranes lined up in parallel."

A National Geographic story about the eye says at least two components of the eye appear to be made from domesticated bacteria. The retinal body of the warnowiid eye may be a plastid, a compartment-like feature found in plant and animal cells. The National Geographic article also describes disagreements among scientists of what exactly the warnowiid does with its complex eye.

A research paper on the warnowiid eye can be found here in the journal, Nature.



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