Great whites shoot up to the surface and bite with great force. When approaching humans,however,they most often move in slowly and bite less hard. They soon discover that humans are not a high-fat meal. "They spit us out because we're too bony," say Aidan Martin, director of ReefQuest Center for Shark Research.
Shark researchers like hypothesize that great whites are actually curious animal that like to investigate things. It's possible that they use their bite not only to kill and eat, but also to gather information. Although such an experience is unlucky for people like Craig Rogers, when sharks bite surfboards or other objects or people,they are likely just trying to learn what they are.