TOEFL Speaking Task 3

In biology, the term “behavioral thermoregulation” refers to the actions an animal takes to control its body temperature by choosing specific environments or altering its posture. Unlike physiological mechanisms such as sweating or shivering, behavioral thermoregulation involves conscious or instinctive choices that help the animal maintain an optimal internal temperature. This can include moving to sunlit or shaded areas, changing orientation to the sun, or adjusting body position to increase or decrease heat absorption. Behavioral thermoregulation is crucial for survival, especially for ectothermic animals like reptiles, which rely on external heat sources to regulate their metabolism.

Professor: Let me give you a clear example from a desert lizard, the chuckwalla. In the morning, when the desert is cool, the chuckwalla emerges from its burrow and climbs onto a dark rock. It flattens its body against the rock, spreading its legs outward to expose as much skin as possible to the sun. This posture maximizes heat absorption, helping the lizard warm up quickly. By midday, when the sun is intense and the ground temperature exceeds 40 degrees Celsius, the lizard moves to the shade under a creosote bush or slips into a crevice between rocks. It also raises its body off the hot sand, lifting its belly to allow cool air to flow underneath. These deliberate moves—choosing sun or shade and adjusting its posture—are classic examples of behavioral thermoregulation, allowing the chuckwalla to keep its body temperature within a safe range for hunting and digesting food.