How Great white sharks made it to the Mediterranean

The Mediterranean Sea is connected to the Atlantic Ocean by the Strait of Gibraltar on the west and to the Sea of Marmara and the Black Sea, by the Dardanelles and the Bosporus respectively, on the east. However
  these connections to other waters are extremely short in magnitude. Why am I bringing up the Mediterranean Sea and these connections to other bodies of water? Please read below the map.

To read an interesting article which discusses how Great  White sharks came to populate the Mediterranean Ocean please click on the following link which will take you to part of the NBC television network website"

http://www.msnbc.msn.com/id/40233285/ns/technology_and_science-science/

You can see a list of all of the species of sharks which live in the Mediterranean Ocean by clicking on the following link:

http://sharks-med.netfirms.com/ 

Source of image:http://greatwhiteshark.netfirms.com/gwtax.htm

Source of map: http://www.welt-atlas.de/datenbank/karten/karte-4-634.gif