托福口语 Task 3

In biology, the concept of 'behavioral thermoregulation' refers to the deliberate actions an animal takes to maintain its body temperature within a viable range. Unlike physiological responses (such as shivering or sweating), behavioral thermoregulation involves conscious choices about movement and posture. For example, an animal might seek shade, bask in sunlight, or change its orientation to the sun. This strategy is crucial for ectothermic animals, which rely on external heat sources to regulate their internal temperature. By actively selecting microenvironments with suitable temperatures, they can optimize their metabolic activity and survival.

Professor: So, let me give you a clear example of behavioral thermoregulation from a desert lizard. The desert iguana lives in the Mojave Desert where ground temperatures can swing drastically—from near freezing at night to over 50 degrees Celsius at midday. During the early morning, the lizard is cold and sluggish, so it presses its body flat against a sun-warmed rock, maximizing surface area to absorb heat. As the day heats up, it becomes too hot, so it climbs onto a vertical plant stem or a small bush, lifting its body off the scorching ground. It also faces its body away from the sun to reduce direct exposure. When temperatures peak, it retreats into a burrow or under a rock, which stays cooler. By moving between these microhabitats, the lizard keeps its body temperature around its preferred 38 degrees Celsius, allowing it to remain active and hunt for insects during the hottest part of the day when predators are less active.