Pet iguanas regulate their body temperature through a process called thermoregulation. They do this by moving between different temperature zones within their enclosure to find the optimal temperature for their needs. Iguanas may bask under a heat lamp to warm up or move to a cooler area to cool down. Additionally, they may also adjust their body posture or seek shade to control their body temperature. It's important for pet owners to provide a gradient of temperatures in the enclosure to allow their iguana to properly regulate their body temperature.