Sharks belong to the fish family, and are characterized by having skeletons that are made from cartilage rather than bone, a series of five to seven gill slits located on both sides of their body for respiration purposes, multiple rows of teeth for feeding which regrow after they have become loose or have fallen out and skin that is composed of a series of scales. Sharks have withstood the test of time; the species has populated Earth for more than 400 million years without exhibiting any drastic evolutionary changes. Although there are only a handful of fatalities related to sharks each year, they are highly predated upon by human beings with over 100 million hunted each year.
Sharks span a large geographical area since different species can adapt to varying environments. Their diets consist mostly of fish, mollusks, plankton, krill, marine mammals, crustaceans and other sharks. They detect their prey through their acute olfactory sensory organs, which can detect the presence of blood in water from miles away.
Dwindling numbers in the shark population have resulted in dire consequences for the entire ecosystem.
Recent studies have indicated that sharks have distinct personalities. The various personalities encourage sharks to attempt differing hunting and survival strategies. Social sharks will often form conspicuous groups while anti-social sharks tend to prefer camouflaging by themselves.