托福口语 Task 4

Today, we're going to discuss a fascinating concept in animal behavior known as 'biological clocks'—internal mechanisms that regulate cyclical activities. A key point is that these clocks are not just about day-night rhythms, but can be adapted to unique environmental pressures. Let me give you two examples. First, consider the intertidal zone, where seaweeds and crabs face alternating periods of submersion and exposure. The purple shore crab has a biological clock that follows the tides, not the sun. It becomes active during high tide to forage for food, even if high tide occurs at different times each day. This clock helps it avoid predators and desiccation. Second, think about the honeybee. Bees use a time-memory to associate food availability with specific times of day. For instance, if a flower patch opens only at 8 AM, bees will return to that patch at that time over several days, even in laboratory conditions without external cues. This shows their internal clock adjusts to reliable, though periodic, food sources. Thus, biological clocks are finely tuned to the most salient environmental cycles, enabling survival and efficiency.