Ethology

1       Sharks are rather intelligent creatures. It is popular belief that sharks are unintelligent creatures and that their sole purpose is to feed on whatever they can find. This perception came about because of the negative light that sharks often fall under. However, much research has been done on their intelligence. Many studies have proved that sharks are intelligent creatures that also exhibit problem-solving skills, possess a sense of curiosity, and have memory. One specific example that researchers have studied for their sense of curiosity is to expose sharks to two objects: one in the shape of a seal, and the other in the shape of a square. Because sharks are rarely ever exposed to anything in the shape of a square, most of the sharks in this study swam towards the square because they were curious about what it actually was. Sharks heavily rely on their sense of smell to attack prey. When they are attacking for prey, they are specifically detecting blood. Sharks can sense a drop of blood in 100 liters of water. Also, they can detect electric charge. They can specifically detect 0.005 microvolts of electric charge. These two skills are advantageous to sharks because this is their method of detecting any kind of prey that may be hiding. 

http://www.youtube.com/watch?v=IIp006jobp0