The average shark is neither menacing nor malevolent. Sharks, as a group, have remained essentially unchanged in form and function for hundreds of millions of years. Perhaps because of their long evolutionary history, sharks exhibit a remarkable variety of highly specialized adaptations. Sharks have a keen sense of smell, unusual blood chemistry, and have developed a mysterious abilities of detecting the faintest of electrical fields, among many other unique adaptations.
All sharks are predators, and usually exist at, or close to, the apex of their food chains.
As such, they are important indicator species in examining marine ecosystems as a whole, and may be important in regulating other species' densities. Compared with more commercially important groups of fishes, research on shark ecology and biology is sparse. However, enough information exists to suggest that most grow and mature slowly, and produce few young compared with other species of fishes. The low reproductive rate of many sharks implies that sharks should be highly vulnerable to current commercial fishing practices, and there is a history of collapse in past shark fisheries. This suggests that a new, more conservative approach needs to be taken concerning the fishing of these animals.