Sir David Attenborough

Our planet may be home to 30 million different kinds of animals and plants. Each individual locked in its own life-long fight for survival.

Everywhere you look, on land or in the ocean, there are extraordinary examples of the lengths living things go to to stay alive.

Vast movements of ocean and air currents bring dramatic change throughout the year.

And in a few special places, these seasonal changes create some of the greatest wildlife spectacles on earth.

Reptiles and amphibians are sometimes seen as simple, primitive creatures. That's a long way from the truth. The fact that they are solar-powered means that their bodies require only 10% of the energy that mammals of a similar size require. At a time when we ourselves are becoming increasingly concerned about the way in which we get our energy from the environment and the wasteful way in which we use it, maybe there are things that we can learn from Life in Cold Blood.

A hundred years ago, there were one and a half billion people on Earth. Now, over six billion crowd our fragile planet. But even so, there are still places barely touched by humanity.

This series will take you to the last wildernesses and show you the planet and its wildlife as you have never seen them before.

Three and a half million years separate the individual who left these footprints in the sands of Africa from the one who left them on the moon. A mere blink in the eye of evolution. Using his burgeoning intelligence, this most successful of all mammals has exploited the environment to produce food for an ever-increasing population. In spite of disasters when civilisations have over-reached themselves, that process has continued, indeed accelerated, even today. Now mankind is looking for food, not just on this planet but on others. Perhaps the time has now come to put that process into reverse. Instead of controlling the environment for the benefit of the population, perhaps it's time we control the population to allow the survival of the environment.

If we and the rest of the backboned animals were to disappear overnight, the rest of the world would get on pretty well. But if they were to disappear, the land's ecosystems would collapse. The soil would lose its fertility. Many of the plants would no longer be pollinated. Lots of animals, amphibians, reptiles, birds, mammals would have nothing to eat. And our fields and pastures would be covered with dung and carrion. These small creatures are within a few inches of our feet, wherever we go on land – but often, they're disregarded. We would do very well to remember them.

Birds were flying from continent to continent long before we were. They reached the coldest place on Earth, Antarctica, long before we did. They can survive in the hottest of deserts. Some can remain on the wing for years at a time. They can girdle the globe. Now, we have taken over the earth and the sea and the sky, but with skill and care and knowledge, we can ensure that there is still a place on Earth for birds in all their beauty and variety. If we want to. And surely, we should.

Dwarfed by the vast expanse of the open ocean, the biggest animal that has ever lived on our planet. A blue whale, 30m long and weighing over 200 tonnes. It's far bigger than even the biggest dinosaur. Its tongue weighs as much as an elephant, its heart is the size of a car and some of its blood vessels are so wide you could swim down them. Its tail alone is the width of a small aircraft's wings. Its streamlining, close to perfection, enables it to cruise at 20 knots. It's one of the fastest animals in the sea. The ocean's largest inhabitant feeds almost exclusively on one of the smallest krill, a crustacean just a few centimetres long. Gathered in a shoal, krill stain the sea red. A single blue whale in a day can consume 40 million of them. Despite the enormous size of blue whales we know very little about them. Their migration routes are still a mystery and we have no idea where they go to breed. They are a dramatic reminder of how much we still have to learn about the ocean and the creatures that live there. Our planet is a Blue Planet.

Ever since we arrived on this planet as a species, we've cut them down, dug them up, burnt them and poisoned them.

Today we're doing so on a greater scale than ever.

I have had the fortune to meet some of the planet's most enchanting creatures. But some stand out more than others because of their intriguing biology. Our knowledge of some of these creatures extends back centuries. Others we've discovered more recently.