8/13 David Attenborough looks at the advantages of birds' feathers.
BBC Two except East, South East, Yorkshire
7/13 How reptiles were the first backboned creatures to solve the problems of living on land. (R)
6/13 When fish crawled from the water onto land and became amphibians, 350 million years ago. (R)
5/13 David Attenborough looks at some of the 30,000 species of fish. (R)