1 x 50:00 min In their struggle to survive, undersea animals have evolved a dazzling arsenal of defences, from armoured shells to stinging cells. Yet for every innovation in defence, nature has devised a counter-ploy, a strategy that ensures that neither predator nor prey will ever win the deadly game. From corals to moray eels and killer whales, the sea swarms with predators, and fewer than one marine creature in a billion escapes death in the jaws of another.