Editor, Earth News
Sir David Attenborough presents his selection of 50 of his most memorable natural history moments
"You have to behave properly. And you mustn't conceal yourself too well. If you suddenly appeared close to them and took them by surprise, then they would almost certainly charge."
A few moments after television viewers heard these words, they saw Sir David Attenborough being cuddled by the very group of mountain gorillas he had just described, lying alongside a huge male silverback, as two young infants inquisitively attempted to remove his shoes.
The iconic sequence, filmed more than 30 years ago in the forests of Rwanda, helped reshape our perceptions of this great ape, and has become a television classic.
It now ranks among Sir David's most favourite moments making wildlife documentaries, which are being made available to audiences online via the
BBC Wildlife Finder.
Other sequences include filming Darwin's frog in the forests of southern Chile.
A number of males, just a few centimetres long, gather before apparently eating newly fertilised eggs laid by a female. The males don't swallow the eggs, however, but store them in their vocal pouches, where the eggs develop into wriggling tadpoles. The males are effectively "struck dumb" by their own offspring.
Sir David has also chosen his film of the coelacanth, the extremely rare fish that is often described as a living fossil, in part because it was thought to have died out tens of millions of years ago.
He also marks the huge surprises found filming deep under the world's oceans and even among communities of bacteria.
"The natural world is the greatest source of excitement of visual beauty and intellectual interest of so much that makes life worth living.
"And that's why I got involved in wildlife film-making in the first place," Sir David told the BBC.
Watch as Sir David Attenborough first met the mountain gorilla
"When I first started out, there was so much of the natural world we were unable to film. The cameras, the lighting, the size of the equipment all meant that the extremely small, the very large, the ultra fast, or the infinitesimally slow, were beyond our reach.
"In the last 30 years things have changed out of all recognition. We can now film everything. From the giants of the world's oceans, to the small invertebrates.
"State of the art high-speed cameras let us demonstrate exactly what goes on in some of the natural world's most dramatic events, lightning fast action that just can't be perceived by the human eye.
"At the other end of the scale, sophisticated time lapse helps us make sense of events that would take too long to show in film. We are now able to find out and show more about the world's species, their habitats and how they are adapted to life on our planet than ever before."
This embrace of new technologies has now been taken a step further, by harnessing the power of the internet to make these iconic sequences available to online audiences, says Sir David.
"And who knows where the lastest HD and 3D technologies will take us.
"It has always been my hope that through filmmaking I can bring the wonder of the natural world into people's sitting rooms, inspire people to find out more and to care about the world we share."
To view all of Sir David Attenborough's favourite moments, go to the
BBC Wildlife Finder