Hammerhead sharks (sphyrnidae sphyrna) are headstrong, independent, and adventurous. They have seemingly endless amounts of energy. 
The distinctively shaped hammerhead is called a cephalofoil.  The function of the laterally expanded head is unclear, but hypotheses include greater maneuverability and lift, better olfactory resolution, enhanced binocular vision and superior mechanoreception. They can swim at a speed of 25 miles per hour.
Sailors and swimmers will sometimes get tattoos of the hammerhead shark as a sort of talisman or good luck charm that will ward off other dangerous sharks that may harm them.
Personally collected Compadre Voyage
18"L x 12"W x 7.5"H