Are Sharks Colorblind?

I was out for lunch with my Convoy Lunch Brigade group a few weeks ago.  We were talking about wet suits and how uncomfortable they are, and we all had hilarious stories to tell of trying to wiggle into wetsuits and put on flippers for a snorkel adventure.  Then the conversation turned to the Solana Beach veterinarian  who was training for a triathlon a few years ago and was attacked and killed while swimming along off Fletcher's Cove.  He was wearing a full black wet suit, and one of the women at lunch said the shark might have mistaken him for a seal.  We talked about whether sharks were colorblind, and the consensus at lunch was that they were not.  I had to come home and check that out.

Sharks are unable to distinguish colors, even though their close relatives rays and chimeras have some color vision, according to new research by Australian scientists.  Their study shows that although the eyes of sharks function over a wide range of light levels, they only have a single long-wave-length-sensitive cone type in the retina and therefore are potentially totally color blind.
The new research on how sharks see may help to prevent attacks on humans and assist in the development of fishing gear that may reduce shark bycatch in long-line fisheries.  The study shows that contrast against the background, rather than color per se, may be more important for object detection by sharks.  This may help us to design long-line fishing lures that are less attractive to sharks as well as to design swim wear and wetsuits that have a lower visual contrast to sharks.

My friends at lunch mentioned that in Australia one finds wetsuits in many colors, not just black as we have here in the U.S.  They thought this was to keep the sharks away, but after reading this article on sharks and their lack of ability to differentiate colors, red or white or blue wetsuits will not keep sharks away.  As we all know, swimming alone is never a good idea for many reasons, shark attacks being just one reason.  Sharks are colorblind.  This might be new information to you, as it was to me.  Just thought you should know.