The island of Barro Colorado in the Panama Canal is full of mysteries, some involving the wide diversity of wildlife, and some involving the island itself. Every year, hundreds of scientists and students come here to uncover the rainforest's secrets, but this year is very different. The island is running dry and no one knows why. Follow several research teams as they observe, experiment, and conduct research in this pristine habitat, and most pressing of all, try to find out what happened to the rain and when it will come again.
In this episode Brian uncovers how the stunning diversity of shapes in the natural world are shadows of the rules that govern the universe. In Spain he shows how an attempt by hundreds of people to build the highest human tower reveals the force that shapes our planet. In Nepal, honey hunters seek out giant beehives that cling to cliff walls. The perfect hexagonal honeycombs made by the bees to store their honey conceal a mathematical rule. Off the coast of Canada, Brian explains how some of the most irregular, dangerous shapes in nature - massive icebergs that surge down from Greenland and into shipping lanes of the Atlantic - emerge from a powerful yet infinitely small force of nature. Even the most delicate six-sided snowflake tells a story of the forces of nature that forged it.
A close-up view of sex, bug-style, as David Attenborough talks viewers through the different ways in which creepy-crawlies reproduce. Size matters for the minuscule male orb spider, creepily sneaking up on its intended and trying to mate without her noticing, while there's no rest for the lothario-like butterfly, which has plenty of notches on its proverbial bedpost. However, the harvestman spider has no use for sex at all, and reproduces by cloning itself.
The big blue is the world's greatest wilderness, far from shore and many kilometres deep. It's a vast marine desert where there is little to eat and nowhere to hide. Yet it's home to some of the biggest and most spectacular creatures on earth. This episode reveals what it takes to survive in this savage and forbidding world. We witness feats of incredible endurance, moments of high drama and extraordinary acts of heart-wrenching self-sacrifice. Every animal in the big blue must find their own unique way to survive.