In Episode 1 Nature's Microworlds travels to the Galapagos Islands, home to a myriad of bizarre and unique creatures, endemic to these islands, but how did they get here? And what is the key to these extraordinary islands that allows them to thrive? Steve Backshall reveals that this key holds not just the secret to life here but also to how Darwin was able to leave with the ideas that would revolutionize biology.

In Episode 2 Nature's Microworlds takes a look at one of the most famous habitats on the planet, the Serengeti, in East Africa; a vast grassland that is home to some of the greatest concentrations of herbivores in Africa as well as predators. But how does it do it? What is the key to this exceptional grassland that allows such density and diversity?

Episode 3 explores the Microworld of the Namib Desert and discovers its key characters and the ingenious adaptations that allow them to cope with the harsh environment. The secret to life in this unique ecosystem is revealed as sea fogs and detritus, blown in across the desert by the winds. These airborne water and food sources are the key to life in Africa's oldest desert.

Episode 4 journeys through the marine ecosystem of Monterey Bay, California, where a giant kelp forest hosts one of the most diverse marine ecologies in the world. The secret to the balance of this ecosystem is a keystone species, the Sea Otter. The sea otter feeds on sea urchins and so keeps their numbers under control, preventing them from destroying the kelp habitat. When these otters were hunted for their fur in the Eighteenth century, the bay's ecosystem collapsed. Now scientists understand the importance of protecting this keystone species.

Episode 5 looks at Canada's Coastal Forest, part of an ancient forest system of redwoods, spruce and cedar, that stretches along the coast from Northern California up to Southern Alaska and is home to some of the largest aggregations of top predators in North America. The trees of this forest are huge and forest productivity here rivals even some of the world's biggest tropical rainforests. Steve Backshall narrates an exploration of where the nutrients come from that fuel the growth of these giant trees and supports predators like brown bears, bald eagles, gray wolves and gray owls.

Episode 6 explores the Great Barrier Reef, the largest reef on the planet. Steve Backshall narrates an investigation into not only how it got so big, but also, how the reef survives on the Australian coast at all. The Great Barrier Reef's immense size is revealed as a mosaic of environments not just the huge coral reef but sea grass meadows and island habitats as well. However, scale isn't the only success of this Microworld. The reef exists in nutrient poor waters, on the face of it too poor to support all this life so how has this amazing Microworld come about in the first place? Steve reveals the unique relationship between the coral and an alga, which is the key to this entire ecosystem.

Episode 7 examines the Red Centre of Australia, one of the most inhospitable environments on Earth yet it teems with an extraordinary array of wildlife most of which is found nowhere else. Steve Backshall shows how the secret to Australia's diversity and peculiarity is its rainforest past, long isolation and the influence of El Nino. A small pocket of palm trees found right in the very heart of the continent are testimony to a time when it was completely covered in a vast rainforest. As the continent drifted and dried out, the rainforest disappeared and the animals have slowly adapted and radiated to fill every niche in the desert. An array of desert birds, mammals, reptiles and amphibians have evolved as a result.

Episode 8 shows the effects on Yellowstone Park when wolves were reintroduced into its environment. Steve Backshall examines how the reintroduction of this apex predator has set off a cascade of events that have reverberated through the food chain. The beaver population has increased, whilst numbers of Coyotes have sharply declined. This has allowed one of North America's most endangered species - the pronghorn antelope - to benefit. Elk are the most numerous grazers in the park, but the fear of being hunted by wolves has radically changed their grazing habits.

In Episode 9 Steve Backshall investigates what makes the Amazon so diverse, he looks at the nutrient poor nature of the rainforest and discusses the strategies that the life in the jungle employs to make the most of the little nutrients available before the rain washes it away. The programme includes humming birds, giant otters, leaf eaters, fungi and nutrient recyclers, giant river turtles and pygmy marmosets. Steve discovers that the relationship between the trees and a mycorrhizal fungus in the soil holds the key to the tree ability to grow in such a nutrient poor environment.

In Episode 10 Steve Backshall takes a look at the archipelago of Svalbard in the Arctic Circle and tries to unpick exactly how life can exist in such a cold, dark place. He follows the fortunes of the islands residents and visitors through the winter and brief summer, polar bears, ringed seals, sea birds and reindeer all feature in the food web but he discovers that the whole ecosystem is driven by the primary producers and the bottom of the food chain, phytoplankton and zooplankton. A huge level of productivity occurs in the Svalbard area. Fifty per cent of the entire Arctic's primary production happens here; Steve discovers that this is due to the gulf stream that extends all the way from the Caribbean.

In Episode 11 Steve Backshall examines what is by far the largest ecosystem on our planet - the deep sea. From jellyfish with 40 meter long tentacles, fish with headlights and terrifying looking ""vampire squid"" it contains some of the most extraordinary and bizarre life forms on the planet. There is even life on the deep sea bed, where armies of sea urchins, giant woodlouse and deep sea crabs feed from a thick layer of sediment. The most surprising discovery Steve makes is the existence of large communities of animals around volcanic vents.

Episode 12 looks at the Scottish Highlands, home to some of the most iconic British wildlife and considered one of the last truly wild places in the UK. Since the Ice Age the Highland landscape has undergone a transformation from dense forest to wide open space; caused by changes in climate and human land use. The Highland wildlife needs both these habitats to thrive and for this balance to be struck we discover that humans have a key role to play.

In Episode 13 Steve Backshall narrates an investigation into what makes the Okavango such a diverse, wildlife rich place, and looks at how an inland delta can exist at all. He looks at the physical characteristics of the environment that mean the water doesn't simply flow away to the sea. He discovers that not only is it the geographical character of the area that makes the delta what it is but also the Okavangos living inhabitants too. The plants and the hippos engineer their environment in such a way that the water does not stagnate and the environment is continually kept in a cycle between swamp and grassland, without which it could not support such a rich diversity of wildlife.