[CINC] shark vision

[Noel & Kathleen Van Slyke]

On a whale watching boat recently I had a visitor ask me*if sharks, 
particularly Great White Sharks had color vison.*  Not knowing the 
answer, I took the visitor's e-mail, began researching, and ran into 
potentially contradictory information.  Shauna suggested that I contact 
Ralph Collier, which I did.  I am placing a summary of what he said in 
case anyone else gets the same question.

"Sonny Gruber and Joel Cohen published their analysis /"Visual System of 
the White Shark, Carcharodon carcharis, with Emphasis on Retinal 
Structure"/ in /'Biology of the White Shark',/ Southern California 
Academy of Sciences, Volume 9, 24 May 1985. They concluded that *the 
ratio of rods and cones in the retina of the white shark were similar to 
that of a human eye, suggesting that they do have color vision but what 
spectrum shift might occur due to their water environment is unknown."*

*The**re has been some research done recently on sharks in **Australia 
on 17 **types of sharks (**this research did not include the **Great 
White Shark) **which indicated most sharks do not have color vision. * 
One site that talks about that research is 
http://www.sciencedaily.com/releases/2011/01/110118092224.htm. and 
*Ralph Collier said the information on that site was accurate. *

I also had read 
http://www.elasmo-research.org/education/white_shark/vision.htm which 
has some detailed information on the eye of the Great White Shark and 
Ralph Collier indicated that the author of this material "R. Aiden 
Martin's analysis of the white shark eye is probably the most detailed 
and accurate of any analysis to date."

He also in his e-mail mentioned an event that some of you might be 
interested in.  "Peter Howorth of the Santa Barbara Marine Mammal Center 
and I will be given a lecture on March 1, 2013 at University of 
California Santa Barbara. We will be discussing the relationships 
between white sharks, pinnipeds, and humans. All proceeds will go to our 
respective organizations for our research projects."

Kathy Van Slyke
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