In this episode, Chris Packham uncovers some bizarre events form the natural world. He examines a mysterious die-off of saiga in Kazakhstan, strange holes ripped out of the clouds and uncovers the real reason for a long line of pits carved out of the Peruvian desert. Chris charts the advance of a crab army in Norwegian waters, finds out what is killing off seabirds on remote islands, why spiders are glowing in the dark, discovers chimps with rock dolls and explores strange mineral deposits alive in the caves under France.

• Jody Bourton

• Chris Packham