With much of it covered in ice all year round and with no daylight from October to March, the Arctic Ocean is one of the world's most remarkable oceans. Its home to a multitude of unique life forms, all highly adapted to cope with the extreme and seasonal conditions. The impacts of climate change are more strongly felt here than anywhere else in the world.

From flightless cormorants hunting underwater to giant tortoises courting on the rim of an active volcano, a look at the hidden side of Galapagos, revealing why it is such a fascinating showcase for evolution.

Birds owe their global success to feathers - something no other animal has. They allow birds to do extraordinary things. For the first time, a slow-motion camera captures the unique flight of the marvellous spatuletail hummingbird as he flashes long, iridescent tail feathers in the gloomy undergrowth. Aerial photography takes us into the sky with an Ethiopian lammergeier dropping bones to smash them into edible-sized bits. Thousands of pink flamingoes promenade in one of nature's greatest spectacles. The sage grouse rubs his feathers against his chest in a comic display to make popping noises that attract females. The Vogelkop bowerbird makes up for his dull colour by building an intricate structure and decorating it with colourful beetles and snails.

Few sounds are more beautiful or moving than the underwater songs of the humpback whale. Male whales compete with their songs, which often last for 10 minutes at a time, and can be repeated for hours on end. Whales separated by thousands of miles of sea will sing almost identical songs. Researchers have found that the songs change throughout the breeding months, following a mysterious pattern repeated across the waves. Whales also use sound to hunt. To catch herring, humpback whales release a stream of bubbles to form a shimmering, circular fishing net. Emitting a repetitive loud scream, they scare the fish into a tight ball, then lunge out of the water to swallow the shoal whole. Now it seems that the long-held image of the gentle giant must change to one of a ferocious and opportunistic hunter.