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  • In Gansbaai, the largest white shark ever caught was at Danger Point and measured up to 5.9m. The exact world record white shark is a contested issue, but chances are it is between 6-7m.

  • If you see a white shark in the water don’t panic. Chances are high that the shark has already detected you and isn’t interested. White shark attacks are normally associated with poor visibility, so avoid murky conditions.

  • White sharks have a unique system called a “counter current heat exchange”, which keeps their body  tempreture +/- 7C above the surrounding water temperature. 

  • All sharks have an incredibly unique system on the tip of their nose called the “ampillae of Lorenzini”. These are small pores filled with a gel that transmits the electrical currents in the water to the shark’s brain so that it can assess its environment.

  • White sharks give birth to live young (not eggs), and they give birth to 6-8 pups at one time. Pups are usually between 1.0-1.5m in length and are born with teeth.

  • Body language has been a well documented form of shark communication and has identified body arching, jaw gaping, and other postures as specific social tactics.

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How do you tell individual white sharks apart from each other?

Wednesday, May 30, 2012 |  0 Comment Tags: dorsal fin ID, shark fins,

Author: Michelle Wcisel (Marine Biologist)
To Michelle, a born and bred American from Michigan, the sea resembles another planet within Earth where intelligent "extraterrestrial" beings and thriving systems flourish in the depths where there is neither oxygen nor sunlight. "So many of us gaze at the stars in wonder when we should be looking into our oceans!"

While there are many ways to tell sharks apart from eachother, like scars and body markings, most white shark researchers use a technique called "dorsal fin ID".  All white sharks are born with 'dorsal fins', the fin at the top of the shark made so famous by Jaws.  This fin is made out of cartiledge, the same substance that makes up your ears and the tip of your nose.  These fins are full of patterns of notches which scientists can use to tell white sharks apart.  These notches and coloration are unique to each shark, like a finger print, and we use these fins to track sharks over many years.  Here are some examples of notable Gansbaai sharks and their dorsal fin IDs.



Shark LEGEND, Slashfin, has a very notable fin.  These markings were most probably caused by another shark biting at his fin, which makes this extremely interesting as Slashfin is an adult male.  But not all fins are so easy to distinguish...



This fin comes from Gansbaai resident, Mooney.  This dorsal fin ID was taken of her in 2007... lets see what she looks like in 2009...



See the top notches?  Yup, still Mooney.  Even though she's added some scars in the two years since the last photo, you can still identify her by the notches. 



But not all body markings are created equally.  This shark, spotted in 2011, has been wrapped up in fishing line which has created the dark circular scar running around the head of the shark.  A great way to ID them, but we would rather stick to the doral fins than human caused damage like this...

If you have a white shark question that hasn't been featured yet on the blog, email us by clicking here!

 

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