Watch Nature's Weirdest Events Season 5 Episode 4 Online

Chris Packham investigates and solves the puzzle of strange balls of worms on a road and fish stuck in fences in Texas. He explains how an Australian town became plagued by giant bats, and why so many sperm whales became stranded around the North Sea in 2015. Chris also explores how a robot could help save the Great Barrier Reef, why eagles might be the best defence against dangerous drones and how the discovery of a spider in the Sahara could take us to other planets. Finally, he reveals new discoveries, like a strange alien cocoon in the Amazon, a plant that makes a home for a bat in Borneo and how the discovery of scratch marks on a cave wall in Western Australia sheds new light on an ancient and terrifying mystery.