Single-celled plankton has a human-like eye

VANCOUVER, British Columbia, July 1 (UPI) -- As a new study reveals, warnowiids, a type of single-celled marine plankton, possess a tiny, human-like eye. Researchers believe the Warnowiid dinoflagellates use the eyes to spot prey.

"It's an amazingly complex structure for a single-celled organism to have evolved," study author Greg Gavelis, a doctoral student in zoology at the University of British Columbia, said in a press release. "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."

The eye is so complex (relative to its owner) that researchers first assumed it belonged to another creature that the warnowiid had eaten.

Scientists are not entirely certain how the eye works, but they believe it senses spectral changes as light passes through the translucent bodies of other types of plankton. The shifts in light signal the warnowiid to move in the direction of potential prey.

"The internal organization of the retinal component of the ocelloid is reminiscent of the polarizing filters on the lenses of cameras and sunglasses," explained Brian Leander, senior author of the new study -- published this week in the journal Nature. "It has hundreds of closely packed membranes lined up in parallel."

The warnowiids and their eyes were collected off the coasts of Japan and British Columbia; scientists were able to examine the creature's odd anatomy using electron microscopy. Researchers say the species is an example of convergent evolution, whereby two very types of organisms (warnowiids and animals) can develop similar traits for similar purposes.

"When we see such similar structural complexity at fundamentally different levels of organization in lineages that are very distantly related," added Leander, "then you get a much deeper understanding of convergence."