TOEFL Speaking Task 3

In biology, organisms often develop adaptations that maximize their fitness in a specific environment. One such adaptation is called “behavioral thermoregulation,” which refers to the deliberate actions an animal takes to control its body temperature. This can include moving to warmer or cooler areas, changing posture, or altering activity patterns. Behavioral thermoregulation is crucial for survival because it allows animals to maintain an optimal internal temperature for metabolic processes without relying solely on physiological mechanisms, which are often energetically costly.

Professor: So, let’s look at a classic example—the desert iguana. In the early morning, when the desert sand is still cool, the iguana is sluggish. So, what does it do? It basks on sun-warmed rocks. This raises its body temperature quickly, allowing it to become active and hunt for insects. But by midday, the sand can get scorching hot—over 50 degrees Celsius. If the iguana stayed on the ground, it would overheat. So, it climbs onto a shady bush or a rock crevice, lifting its body off the hot surface. This way, it avoids absorbing too much heat from the ground. By moving between sunny and shady spots throughout the day, the iguana keeps its body temperature within a narrow, safe range. This is a perfect example of behavioral thermoregulation—it’s not about changing its internal physiology; it’s about changing its behavior to control body heat.