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The Outer LimitsBy studying the hydra, a member of an ancient group of sea creatures that is still flourishing, scientists have made a discovery in understanding the origins of human vision. Hydra are simple animals that, along with jellyfish, belong to the phylum cnidaria. Cnidarians first emerged 600 million years ago.
"We determined which genetic 'gateway,' or ion channel, in the hydra is involved in light sensitivity," said senior author Todd H. Oakley. "This is the same gateway that is used in human vision."
The gene, called opsin, is present in vision among vertebrate animals, and is responsible for a different way of seeing than that of animals like flies. The vision of insects emerged later than the visual machinery found in hydra and vertebrate animals.
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