Reptiles and amphibians are animals whose body temperature depends on the temperature of their surroundings and the penetrating infrared radiation of the sun (ectotherm).
Up to a certain degree reptiles and amphibians are able to regulate their body temperature through their behaviour. They will move into the sun or lie on warm rocks. This raised temperature is needed e.g. for hunting for food or for important digestive processes.
As a continuously higher temperature would lead to a higher energy consumption, reptiles will crawl into caves or rock crevices to lower their body temperature. This capacity to change body temperature is called poiklidotherm.
In order to meet the needs of reptiles and amphibians, there should be a heat source in their terrarium that corresponds to their cycle of activity (e.g. a heat spotlight). The wattage of this lamp should provide a temperature comparable to their natural habitat for the place where they lie in the sun. At the same time there has to be a suitable place for them to lower their body temperature in the terrarium (e.g. a cave or a place where they can hide in leaves).