Sinking beneath the waves is a very surreal experience. Your first instinct is to hold your breath. At night, the reef is a ghostly world. Tiny shrim… - David Attenborough

Make a list of all the environmental and social problems that today afflict us and our poor battered planet. – not just the extinction of species and animals and plants, that fifty years ago was the first signs of impending global disaster, but traffic congestion, oil prices, pressure on the health service, the growth of mega-cities, migration patterns, immigration policies, unemployment, the loss of arable land, desertification, famine, increasingly violent weather, the acidification of the oceans, the collapse of fish stocks, rising sea temperatures, the loss of rain forest. The list goes on and on. But they all share an underlying cause. Every one of these global problems, environmental as well as social becomes more difficult – and ultimately impossible - to solve with ever more people.

As I see it humanity needs to reduce its impact on the Earth urgently and there are three ways to achieve this: we can stop consuming so many resources, we can change our technology and we can reduce our population. We probably need to do all three. m31m37-m31s56

The coral's stinging armoury isn't used only for collecting food; they also use it to fight. As has been discovered only comparatively recently, corals, like many animals that live on land, are extremely territorial. But in order to see the battles, you have to speed up time.