Avsnitt 4

Looks at the extraordinary properties of frog and toad skin, showing how it enables them to survive hostile environments. Amphibian skin contains many chemical compounds, including antibiotics, fungicides, anti-viral agents and toxins, which serve as built-in barriers against infection and protection from predators. Scientists in America have even identified an anti-cancer agent in the skin of certain amphibians . One sequence reveals a dangerous and illegal craze in California for toad licking - the skin of some toads contains hallucinogens so powerful that the US Drug Enforcement Agency puts it in the same class as heroin. The programme features toad and frog species from Britain and the continents of Africa, America, Asia and Australia.