TOEFL Speaking Task 3

In biology, the term "behavioral thermoregulation" refers to the active choices animals make to control their body temperature by moving to different environments. Unlike physiological mechanisms, such as sweating or shivering, behavioral thermoregulation involves actions like seeking shade, basking in the sun, or changing posture. This strategy allows animals to maintain an optimal internal temperature for essential functions like digestion and muscle activity, while conserving energy that would otherwise be spent on metabolic processes. It is particularly common in ectotherms, which rely on external heat sources.

Professor: Let’s take a lizard, for example. A desert lizard needs to keep its body temperature around 37 degrees Celsius to be active. In the morning, it’s cool, so the lizard lies on a sun-warmed rock, flattening its body to absorb as much heat as possible. That’s basking. But by midday, the ground gets too hot—over 40 degrees. If the lizard stayed there, it would overheat. So it moves into the shade under a bush or into a small burrow, where it’s cooler. It might also raise its body off the hot sand, lifting its legs to let air circulate underneath. Later in the afternoon, when the sun is less intense, the lizard comes out again to warm up. These deliberate moves—choosing sunny spots, then shady spots—help it keep its temperature stable without using much energy. That’s behavioral thermoregulation.