The reputations and mysteries surrounding sharks far exceeds our understanding of them. Tales of interactions with sharks are often exaggerated or sensationalized. Some 'experts' present their involvement with sharks as heroic efforts or seek to primarily record images of sharks involved in baited, bloody feeding encounters. Public attention is usually drawn to a minority of large, active species. The common image of the large torpedo-shaped shark constantly feeding and moving is misleading.
Sharks are extremely diverse in form, feeding habits, range of movement, and use of habitat.
Some occupy the deep sea and polar regions and others move throughout entire ocean basins during the course of their lives. Shark Biology Sharks are often thought of as highly primitive creatures that have remained unchanged since their first appearance in the oceans. Although sharks have been around for approximately 400 million years, they have undergone many adaptations and specializations during this time. They are believed to have remained relatively unchanged since the time of dinosaurs and the first birds. However, many of the present day sharks, such as the mako or white, are believed to have developed only 50 million years ago.