This episode is available ON-DEMAND to customers of participating TV providers.
To unlock access to full episodes select a provider.
Are you sure you want to Sign Out of your provider account?
You are signed in with your provider account and can watch any available full episodes.
The secret of why jungles have more variety in their animals and plants than anywhere else on land, and the mysterious tale of why this means that a Brazil nut tree needs a little rodent and a rare orchid, in order to survive.