A look at why a seal throw an octopus at a kayaker; why a moth is drinking from the eye of a bird in the Amazon jungle and what surprising creature has been leaping out of the Irish Sea.
The first episode tells how invertebrates became the first creatures of any kind to colonise dry land. Their forerunners were shelled and segmented sea creatures that existed 400 million years ago. Some of them ventured out of the water to lay their eggs in safety, and Attenborough compares those first steps with today's mass spawning of horseshoe crabs off the Atlantic coast of North America.
Some species need to be part of a group to survive--more so when they're in their infancy and taking their first, uncertain steps into the world. Join in the rough-and-tumble lives of black bear cubs, playful meerkat pups, and adorable fur seals.
In this second episode we travel from January to the March equinox. Kate Humble gets closer to the Sun than she has ever been before, whilst Helen Czerski visits a place that gets some of the biggest and fastest snowstorms on Earth.