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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 white sharks sleep?

Tuesday, May 01, 2012 |  0 Comment Tags: shark resting, shark tagging, sleep,

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!"

Shark sleeping patterns have puzzled scientists for many years.  All sharks extract oxygen from the water with their gills, and to do this water must move over and past their gills.  This is called "ram ventilation."  To work around this, many sharks developed spiracles, a little 'nostrile' type opening behind the eye, which they can use to pump water over their gills even when sitting still.  During the process of divergence from ancient shark to modern speed machine, white shark spiracles became small to non-existant. Because of this, white sharks are considered obligate ram ventilators, which means they must constantly move in order to move water over their gills to breath.

But surely, an animal must rest.  While we haven't observed it in the water ourselves, the Dyer Island Conservation Trust has documented tracks of white sharks that they think are resting.  While tracking tagged white sharks, we noticed a few sharks would find small gullies and sit stationary for long periods of time - some for hours - most probably sitting face first into a current letting water still pass over their gills without having to move.  This could be a form of white shark resting, but we'll have to dive down and see it ourselves to be sure (and hope we are right)!

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