Scientists from Australia have used spectrophotometry to examine the light-sensitive cells in shark eyes.  In contrast to the 3 types of photoreceptors we humans have for red, green and blue, sharks only have one type of photoreceptor, suggesting that they can’t distinguish colors.   Sharks probably visualize their world in terms of assessing contrast against background.  Thus, it may be possible to design swimming gear, boats, and fishing gear that are less likely to catch a shark’s eye.

Read about it here in the news: http://latimesblogs.latimes.com/outposts/2011/01/sharks-are-color-blind-shark-attacks.html

and here is the original scientific article recently published:  http://www.springerlink.com/content/05427357r3uw8q35/

Here are a couple video clips showing shark attacks.  The 1st is of some idiots standing in shark infested water, and the 2nd is a scuba diver attacked by a Great White shark.