From Discworld & Terry Pratchett Wiki
A lizard species that has evolved to live on magic. Salamanders look like lizards without a mouth. They live in deserts and sun themselves, absorbing all wavelengths in the Discworld sunlight. The salamanders use the octarine wavelength for their own energy and nutrients, and excrete the rest of the sunlight in much the same way that other animals excrete undigested matters. This excretion also happens when a salamander is surprised. Iconographers exploit this characteristic by keeping salamanders in a cage and using them as flashbulbs. In this capacity, salamanders have some roles in The Colour of Magic, Moving Pictures, The Truth, and most other occasions involving the use of iconography or the work of a newspaper.