托福口语 Task 3

In biology, organisms often develop specialized behaviors to maximize their chances of survival in changing environments. One such behavior is 'behavioral thermoregulation,' which refers to the deliberate actions an animal takes to regulate its body temperature by moving to different microenvironments. This is distinct from physiological thermoregulation, which involves internal mechanisms like sweating or shivering. Behavioral thermoregulation is crucial for ectotherms, or cold-blooded animals, because they rely on external heat sources to maintain optimal body temperatures for activities like digestion and movement. By selecting warmer or cooler spots in their habitat, they can avoid overheating or becoming too sluggish to escape predators.

Professor: Let me give you a clear example from a desert lizard species. These lizards are active during the day, and they need to keep their body temperature around 37 degrees Celsius to move quickly and hunt for insects. In the morning, the desert sand is cool, so the lizards bask in the sun on rocks to warm up. But by midday, the ground becomes extremely hot—sometimes over 50 degrees. If the lizard stayed there, it would overheat and die. So, what does it do? It lifts one leg and then another, alternately, to minimize contact with the hot sand. Then, it quickly runs to the shade under a bush or into a small burrow. It stays there until the late afternoon when the sun is lower and the sand cools down again. Then it comes out to hunt. By moving between sunny and shady spots throughout the day, the lizard maintains a safe body temperature and remains active.