Reptiles are ectotherms i.e. regulate body temperature by behavioural means. preferred body temperature (PBT) = optimum temp for bodily functions ( movement, digestion, feeding, reproduction) reptiles require a range of temperatures to be able to thermoregulate (preferred optimum temperature zone/ POTZ). Sick reptiles seek out the high end of their PBT (`behavioural fever') Primary heat Source - for background/ ambient heat (at the low end of the POTZ). Use heat tapes, mats, or radiant heat from incandescent bulbs, ceramic lamps. Always provide a heat source that is not also a light source in order to provide the correct period of darkness whilst maintaining the vivarium temperature. Secondary heat source - specific areas can be provided with a higher temperature. For lizards, a 50 - 75W bulb directed downwards is generally adequate. For arboreal species this should be directed onto a branch, and onto a rock/ floor area for terrestrial species. Semi-aqautic species require a dry area with a basking light of 50 -75W. A heat pad is used to maintain ambient temperature. Placed over 1/3 side of the vivarium. Ultratherm heat mats generate ultra-infra- red heat and so may be taped to the side of the vivarium where the reptile can bask in the beam. Polystyrene should be fixed to the back of the heatpad, and under the base of a glass vivarium. hot spot overhead bulb (and UV supply if required). Prevent direct contact hot rocks NOT RECOMMENDED warm artificial rocks used to heat reptile by direct contact. Monitoring is important to check range of temperatures. The ambient temp should not exceed the PBT, the temp under hot spot should not exceed the maximum tolerated. Maximum and minimum thermometers and thermostats are essential