Episode one takes us to Antarctica - the coldest, windiest, most hostile continent. Only the toughest can survive here. From Weddell seals that grind back the ice with their teeth, to colourful starfish carpeting the seabed beneath the ice; huge colonies of king penguins crowd any ice-free land, and four-tonne elephant seals fight for territory on the beach. Life comes here because the ocean that surrounds the continent is incredibly rich. Thousands of penguins, seals, albatross, and over a hundred great whales feast on krill baitballs. However, the ocean here is warming - and with that comes an uncertain future.

Asia is the largest and most extreme continent on our planet, stretching from the Arctic Circle in the north to the tropical forests on the equator. The animals here face the hottest deserts, tallest jungles and highest mountains found anywhere on Earth. But the continent has not always looked like this. These extreme worlds were created when India collided with the rest of Asia 30 million years ago, shaping the continent as we know it today. Animals here have adapted to the extreme environments in almost unbelievable ways.

South America - the most species rich continent on Earth.From the volcanoes of the Andes to the Amazon, the world's largest rainforest, animals here must specialise if they are to carve out a niche.In Patagonia, a puma mother draws on a lifetime's experience to catch prey three times her weight. In the cloud forest, rarely seen Andean bears clamber 30 metres into the canopy to find elusive fruit.Poison dart frogs use ingenious methods to keep their tadpoles safe, whilst anacondas stalk capuchin monkeys. At Igauzu Falls, swifts make death-defying flights through one of the biggest waterfalls on Earth.