托福口语 Task 3

In biology, the concept of '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 is crucial for ectotherms (cold-blooded animals) because their internal heat depends largely on external sources. By selecting microhabitats with optimal temperatures, they can maintain vital bodily functions, such as digestion and locomotion, even when the ambient temperature fluctuates significantly.

Professor: Let’s look at a desert lizard, the chuckwalla. On a cool morning, the lizard emerges from its rocky crevice and lies flat on a sun-heated boulder. This maximizes its body surface exposed to sunlight, raising its temperature quickly. As the day heats up, the rock becomes too hot. So, the chuckwalla climbs into a crevice or moves to the shady side of a rock, pressing its body against cooler surfaces. Later, if it needs to digest a meal, it returns to a sunny spot but positions its body sideways to the sun—this way, it absorbs heat without overheating. By moving between sun and shade throughout the day, the chuckwalla keeps its body temperature within a range that allows it to hunt and digest efficiently.