TOEFL Speaking Task 3

In biology, the term "behavioral thermoregulation" refers to the active choices animals make to regulate 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 is common among ectotherms—animals that rely on external heat sources—because it allows them to maintain optimal body temperatures for essential activities like digestion, movement, and reproduction without expending metabolic energy.

Professor: Let me give you a concrete example from a desert lizard species. In the morning, when the sand is cool, these lizards bask on sunlit rocks. They flatten their bodies to maximize surface area, absorbing heat quickly. Once their body temperature reaches about 35 degrees Celsius—their preferred level—they become active, hunting for insects. But as the sun gets stronger around noon, the rocks become too hot. If the lizard stayed, it would overheat. So it moves to a shady spot, like under a bush or into a burrow. There, it lifts its body off the hot ground, allowing air to cool it. By shifting between sun and shade throughout the day, the lizard keeps its temperature within a narrow range, enabling it to digest food and move efficiently. This behavior is crucial for its survival in the desert's extreme temperature swings.