Amphibians are remarkable creatures that have inhabited the Earth for over 350 million years, and exhibit some of the most amazing and diverse life histories. The planet is home to around 7,500 species of amphibian, which occupy an extraordinary number of ecological niches. They are often viewed as indicators of environmental health by ecologists due to their reliance on both aquatic and terrestrial environments to complete their lifecycles. Furthermore, their thin and highly sensitive skin, where much of their respiration occurs, makes them highly susceptible to environmental toxins, disease and radiation.