Inside Nature's Giants

Veterinary scientist Mark Evans joins experts in anatomy, evolution and behaviour in a bid to get under the skin of the crocodile. Meanwhile evolutionary biologist Professor Richard Dawkins explains how little the crocodile has changed since the age of the dinosaurs. The team uncovers the crocodile's incredible jaw muscles, as biologist Simon Watt travels to Florida to test the huge strength of the massive reptile's bite: the most powerful in the animal kingdom. But while crocodiles' spiked teeth are excellent for gripping prey as they plunge into a death roll, they are useless for chewing. So how do these animals manage to digest large chunks of raw meat and bone? As the experts dissect the digestive system and inspect the stomach contents for clues, they reveal the bizarre plumbing between the heart and the stomach that might provide the key to this puzzle. And they also solve the mystery of this crocodile's premature death.

Veterinary scientist Mark Evans acts as guide as a team of experts investigate the giraffe. Creationists question how this extraordinary creature could have evolved such a long neck, but for evolutionary biologist Professor Richard Dawkins the anatomy of the world's tallest animal provides some of the best arguments in favour of Darwinian natural selection. For example, one nerve takes a huge detour up and down the long neck, from the voice box to the brain, via the chest - hardly the work of an `Intelligent Designer'. And, despite its length, the neck still only has seven vertebrae - the same number as almost all mammals, from mice to humans and whales. But it's no wonder the giraffe has the highest blood pressure of any animal; with a heart not much bigger than our own it must pump blood at high pressure around a towering body. It has evolved thick skin that acts as a natural 'G-suit' and a complex circulation system to avoid passing out when raising and lowering its head. And as the dissection team piece together the remarkable evolutionary story of the giraffe, biologist Simon Watt observes them in the field as they eat, forage and fight.