This programme looks at the evolution of fish. They have developed a multitude of shapes, sizes and methods of propulsion and navigation. The sea squirt, the lancelet and the lamprey are given as examples of the earliest, simplest types. Then, about 400 million years ago, the first back-boned fish appeared. The Kimberley Ranges of Western Australia are, in fact, the remnants of a coral reef and the ancient seabed. There, Attenborough discovers fossils of the earliest fish to have developed jaws. These evolved into two shapes of creature with cartilaginous skeletons: wide ones (like rays and skates) and long ones (like sharks).
Losing a parent in the wild can be deadly for young animals, but these orphans got lucky when conservationists stepped in. Meet clouded leopard cub sisters taken in by the Nashville Zoo, a baby wombat raised in an artificial pouch at Tasmania's Bonorong Wildlife Sanctuary, and more.