Plot: What is the most toxic animal on earth? How are porcupine quills helping us in medicine? Why is a rhino armour plated, and it is not to protect them from lions? Professor Ben Garrod discovers the complex ways, from camouflage to deadly toxins, in which the skin helps defend animals against threats of all kinds. From the barbed quills of the North American porcupine to the battering ram of a rhino’s horn, the skin has developed an impressive armoury of weapons and warnings to keep predators at bay