TOEFL Speaking Task 3

In biology, the concept of 'behavioral thermoregulation' refers to the deliberate actions an animal takes to regulate its body temperature by exploiting its environment. Unlike physiological mechanisms such as sweating or shivering, behavioral thermoregulation involves choices—moving to a warmer or cooler location, changing posture, or altering activity patterns. This strategy is common among ectotherms, or cold-blooded animals, which cannot generate their own heat. By seeking out sun, shade, water, or burrows, these animals maintain an optimal internal temperature for essential functions like digestion, movement, and reproduction.

Professor: Let's take a desert lizard, the chuckwalla. In the early morning, after a cool night, its body is cold and sluggish. So what does it do? It climbs onto a sunlit rock, flattening its body to maximize the surface exposed to the sun. This absorbs heat quickly. Once its body reaches an active temperature, it forages for food. But by midday, the desert floor can get dangerously hot. If the lizard stays on that hot surface, it could overheat. So it retreats to the shade under a rock or into a crevice, and it may even press its body against the cooler rock to lose heat. Then, in the late afternoon, when temperatures drop again, it comes back out to bask. This way, the chuckwalla never gets too hot or too cold—it simply moves to where the temperature suits it best.