SHARKS (Their danger and their value)

This is about sharks, their different shapes, their different sizes and growth rates, their mobility, their array of sensing devices, their specialized heat retaining system, their reproduction, their value to sports fishermen, their danger to humans, about shark repellents and other means of protection against dangerous sharks, their meat and fins as sources of food for humans, their skins as a source of tough and special leathers, and an array of pharmaceuticals including heparin-like compounds, vitamin A, omega-3 fatty acids, immune system boosters, potential anti-cancer agents, and much more.