Can sharks go blind

Sharks can only see in shades of grey.

Findings from a study by Australian scientists, released in September 2012, show that sharks' eyes have just one type of cone opsin - or light-sensitive proteins found in the photoreceptor cells of the retina - instead of thevtwo or more that are needed to see colour. Cone opsins are used to help animals see in bright light, and to differentiate between colours.