Friday, January 21, 2011

Sharks don't see in color

Wear white wetsuits to avoid attack
Researchers discovered that the eyes of sharks, including bull and tiger sharks, are not designed to distinguish different colours and so they see the world in black and white.

That means against the light blue of the sea, it would be better to wear light coloured swimwear in order to reduce the contrast with the water... The study backs up statistics from the International Shark Attack File (ISAF) which shows that the vast majority of attacks happen to divers and surfers wearing black wetsuits...
...They found that their retinas had only one kind of cone – or light detector – that was only able to detect light or dark. That means a red apple would be just a dark shade to them.

Humans, in contrast, have three cones to distinguish colour, red, green and blue...
../"We might also be able to use it to design longline fishing lures that are less attractive to sharks … and reduce the huge numbers of sharks that are killed by catch each year."...
Once upon a time, Georgia and I took a cruise out of Ft. Lauderdale, and we had a day wait before we flew out.  I arranged a fishing trip out of Miami in Biscayne Bay.  One of the things the guide had me do was fly fish for reef sharks.  The process was pretty simple; the boat was anchored in channel in the reel, a fish (blue runner) was cut and hung in the water off the boat to attract sharks.  I was handed a 12 weight fly rod with a a huge fly made of chicken feather dyed bright red.  My instructions were simple; "Dangle the fly in front of it's nose, and twitch it once, not twice.

The first shark came in within 5 minutes, I broke the rule and twitched twice, pulled the fly out of his field of view, and it lost interest.  The second, shortly after, was a large Spinner shark, which jumped and spun, much like his name, and broke the 80 lb leader.  The third shark was a Black Tip (it looked a lot like the spinner to me).  It took at least 15 minutes to fight and land it, after which it was released to come back another day:

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