TOEFL Speaking Task 3

In biology, the term “behavioral thermoregulation” refers to the strategies animals use to control their body temperature by changing their behavior rather than through physiological processes. This is crucial for ectotherms, which rely on external heat sources. By moving between sun and shade, altering posture, or changing activity times, animals can maintain an optimal internal temperature for essential functions like digestion and movement. Behavioral thermoregulation is often more energy-efficient than physiological adjustments, allowing animals to thrive in variable environments.

Professor: Let’s take a desert lizard. In the morning, it’s cold, so the lizard lies flat on a sun-warmed rock, spreading its body to absorb maximum heat. This raises its body temperature quickly for hunting. By midday, the sand gets scorching hot. To avoid overheating, the lizard lifts its body off the ground, using its legs to create a small gap for air to cool it. It also moves into the shade of a bush or burrows into cooler sand. In the afternoon, if it needs to digest a meal, the lizard returns to a sunny spot but keeps its body parallel to the sun’s rays, reducing heat absorption while still gaining enough warmth for digestion. These choices—where to go and how to position—are all behavioral adjustments to regulate temperature without sweating or shivering.