Possibly no other creatures are as mythologized — or as misunderstood — as sharks. Blockbuster thrillers and sensationalized media have fueled the belief that sharks are monsters: unthinking, bloodthirsty, vengeful and primitive. While they are ancient creatures, having emerged long before the first dinosaurs, after 400 million years the 500 or so known shark species have adapted to their ecological role.
Sharks' adaptions including light, flexible skeletons of cartilage, teeth replaced without limit and skin covered by a hydrodynamic surface of tiny tooth-like structures. Their keen sense include one that detects electrical signals given off by prey and enables navigation by Earth's magnetic field. Their nervous systems also are adapted to sense miniscule water movements, such as the struggles of a far-off fish.
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