(January 19, 2011) Sharks are able to smell blood from miles away but it is unlikely that they know what colour it is, as a new study suggests that sharks are colour blind.

They have successfully prowled the oceans for millions of years as they have an impressive suite of sensory systems, including well developed eyes and a large area of the brain devoted to vision. However, over the last few decades conflicting data has sparked a debate about whether sharks can actually see colours.

For the full story visit nationalgeographic.com