[2] The score for the main films was composed by David Poore and Ben Salisbury, whilst the music for Under the Skin was written and performed by Tony Briscoe.

Filming began in the early part of 2006 and, as with Attenborough's previous series, the production team travelled the world to photograph the required sequences.

In May 2006, Attenborough celebrated his 80th birthday in the Galápagos Islands while filming giant tortoises, one of which, called Lonesome George, was thought to be the same age.

However, for Attenborough's close encounter with a spitting cobra, a captive snake that was used to being handled was placed in a natural setting and the presenter wore a face visor.

Other examples of 'pets' being used were for sequences depicting the lassoing tongue of a chameleon (which had to be filmed at ultra-high speed) and the digestive system of a python (which was enhanced by computer-generated imagery).

[7] Attenborough confirmed on the penultimate edition of Parkinson, broadcast on 16 December 2007, that he did not intend to retire completely and would still make occasional single documentaries, rather than any more series.

Attenborough begins in the Galápagos Islands, using thermal imaging to demonstrate how marine iguanas warm their bodies by basking in the sun before feeding.

Attenborough visits Australia to illustrate how they became the first back-boned creatures to colonise land: the lungfish, which is capable of breathing air, and whose ancestors became the first amphibians.

In North America, the marbled salamander spends most of its life on land, yet is still able to retain the necessary moisture in its skin through the damp leaf litter.

A female caecilian is filmed with her young, whose rapid growth is discovered to be the result of eating their mother's skin – re-grown for them every three days.

In southern Australia, Attenborough uses a baited fishing rod to attract the attention of a rare pygmy bluetongue skink, thought to have been extinct for over thirty years until it was rediscovered in 1992.

Alongside South Africa's Orange River, large groups of flat lizards feed on the swarms of black flies, but the males also use the occasion to indulge in social squabbling.

With the aid of infrared cameras, a timber rattlesnake is shown lying in wait for a mouse and sensing its repeated path before despatching and eating it.

In the open ocean, male sea turtles attempt to separate a rival from its mate by attacking and overwhelming the pair, stopping them from taking in air.

In northern Australia, Attenborough observes a large gathering of crocodiles at a flooded coastal road: they time their arrival to ambush migrating mullet.

The complex communication and body language of the American alligator is investigated and in Argentina, the calls of young caimans help their mother locate and lead them to a nursery pool.

In Venezuela, a female spectacled caiman in charge of an entire crèche leads the infants from a drying river bed on a trek to permanent water.