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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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How Salmon See the World Anew
18 March 2004 (All day)
If you were used to finding food by day then suddenly switched to chasing your dinner in the dark, night-vision goggles might be a necessity. The concept applies to salmon too: New research suggests that the fish adjust the light-sensitive pigments in their eyes as they age and move to deeper waters.
When young pink salmon graduate from shallow streams to the open ocean, they also change their eating habits--from nibbling plankton on the surface to hunting fish in deep water. Scientists suspected that the salmon visual system adapted as the fish moved from shallow waters dominated by ultraviolet light to deeper waters filled with blue and green light, but they had only hunches about how this might happen.
The new study suggests that the salmon's secret is shuffling the light-sensitive pigments inside their cone cells--nerve cells in the retina that respond to light. Iñigo Novales Flamarique and Christiana Cheng of Simon Fraser University in Burnaby, British Columbia, came to that conclusion by examining the retinas of young Pacific pink salmon. They couldn't find any cone cells with blue-light sensitive pigments. But in the retinas of older salmon, such cones were common. And in fish of intermediate age, the pair spotted UV-light sensitive pigments at the cell's tip, but blue-light sensitive pigments at the base, suggesting the salmon were pumping those pigments into their UV-light sensitive cones. The scientists report their findings in the 18 March issue of Nature.
“The work is very interesting,” says Juliet Parry of University College London, adding that many researchers had assumed that salmon tweaked their vision by replacing entire cone cells, not merely replacing the pigment. Novales Flamarique suspects this potential for pigment change may be widespread in vertebrates and has been overlooked because it's difficult to detect in the tiny cone cells. Clearly there is more to color vision than meets the eye.