Simple communication between a pair of neighboring cells allows tiny marine worms to move toward light using a sensory organ believed to be an ancient precursor of the eye, according to a study out this week in Nature. "It's remarkable that a primitive organism of the ocean, a living marine zooplankton, has the sophisticated ability to move in response to light with a pigment-photoreceptor cell combination," linkurl:Russell Fernald,; an evolutionary neuroethologist at Stanford who was not involved in the study, told The Scientist. He added that the paper provides "proof that a simple pair of cells can give directive information." The vertical migration of plankton in response to light constitutes the largest biomass transport on Earth. Researchers have believed that the eyespots of multicellular zooplankton larvae, comprised of a single photoreceptor and shading pigment cell, are responsible for phototaxis, or movement toward light, but the mechanism has never been identified....

The eyespots of Platynereis larvae allow it to move toward light

PlatynereisThe ScientistChlamydomonasImage courtesy of Arendt, D. and Jekely, G., EMBLThe Scientist

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