JUVENILE salmon adjust their colour vision as they move into deeper waters to feed. The switch from making one kind of photoreceptor pigment to another may help them see better in the different quality of light.
Iñigo Novales Flamarique and Christiana Cheng of Simon Fraser University in Burnaby, Canada, measured the sensitivity of light-sensitive cones in young pink salmon’s eyes to different wavelengths of light. Just after the salmon hatched, one type of cone, known as a “single” cone, was most sensitive to ultraviolet light with a wavelength of about 370 nanometres.
By the time the fish had doubled…
