How Good Is A Shark's Eyesight?

Some of the shark senses — particularly smell, taste, and hearing — are famously sharp. But around one sense, vision, the debate has been much more muddled. So just how well does a shark really see?

Shark biologists Lisa Natanson and Cami McCandless from NOAA's Apex Predator Program joined us today to take our questions about the life and physiology of sharks — including this one on the ability of sharks to perceive color:

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Hi Lisa & Cami, thanks for taking the time to answer our questions.

I've read somewhere that sharks maybe color blind and by wearing wetsuit that matches the color of the ocean (greenish-blue here in Southern Cali.) will make you less likely a target for the sharks. Any truth to this?

Lisa

I have not read this research however it is hypothesized that the shadows are really what sharks are on the lookout for. Many fish have white/silver undersides and dark backs, this is so that from below they blend against the light of the surface and from above they blend in with the dark from the depths. If you think of the color of a seal it is much like the dark color of the sea and sharks can certainly see them. So I would not really bet on that idea.

Even setting aside the issue of color blindness, however, it seems that we would do well not to underestimate the seeing abilities of sharks.

The Florida Museum Of Natural History describes the eyes of sharks as being not so very dissimilar to our own — like our eyes their pupils open and close and the core parts are the cornea, iris, lens and retina. There is however one rather incredible exception, that may make their vision more catlike than humanlike:

Sharks, similar to cats, have a mirror-like layer in the back of the eye referred to as the tapetum lucidum. This layer further increases the intensity of incoming light, enhancing the eye's sensitivity to light. Although it was once thought that sharks had very poor vision, we now know that sharks have sharp vision. Research has shown that sharks may be more than 10x as sensitive to light as humans. Scientists also believe that sharks may be far-sighted, able to see better at distance rather than close-up, due to the structure of the eye.

Image: White Tip Reef Shark / NOAA