From the weird cookie cutter shark, which bites cookie-shaped circles out of its prey, to the macabre sand tiger shark, whose young devour each other in the womb, this is a close-up look at the most extreme predators nature has to offer.From the weird cookie cutter shark, which bites cookie-shaped circles out of its prey, to the macabre sand tiger shark, whose young devour each other in the womb, this is a close-up look at the most extreme predators nature has to offer.