This single-celled bug has the world’s most extraordinary eye

Image: Fernando Gómez/Laboratory of Plankton Systems, Oceanographic Institute, University of São Paulo

by Michael Le Page

It is perhaps the most extraordinary eye in the living world – so extraordinary that no one believed the biologist who first described it more than a century ago.

Now it appears that the tiny owner of this eye uses it to catch invisible prey by detecting polarised light. This suggestion is also likely to be greeted with disbelief, for the eye belongs to a single-celled organism calledErythropsidinium. It has no nerves, let alone a brain. So how could it “see” its prey?

Fernando Gómez of the University of São Paulo, Brazil, thinks it can. “Erythropsidinium is a sniper,” he told New Scientist. “It is waiting to see the prey, and it shoots in that direction.”

Erythropsidinium belongs to a group of single-celled planktonic organisms known as dinoflagellates. They can swim using a tail, or flagellum, and many possess chloroplasts, allowing them to get their food by photosynthesis just as plants do.

Others hunt by shooting out stinging darts similar to the nematocysts of jellyfish. They sense vibrations when prey comes near, but they often have to fire off several darts before they manage to hit it, Gómez says.

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