Color Blind Sharks?

According to an article for National Geographic News, new studies show that some species of sharks appear to lack cone cells, cells in the retina of the eye that help distinguish colors. Using a similar method to a previous study that proved rays and chimaeras had color vision, scientists at University of Western Australia determined that "no cone cells were observed in 10 of the 17 species, while only one type of cone cell appeared to be present in the other 7. This suggests that these sharks cannot tell different colors apart." Read the full article here.