托福口语 Task 4

Today we're going to talk about a fascinating concept in animal behavior called 'biological clocks.' These are internal mechanisms that allow organisms to anticipate and prepare for regular changes in their environment. However, the key point I want to emphasize is that these clocks are not just simple responses to external cues; they are finely tuned to the specific rhythms of an animal's ecological niche. Take the intertidal zone, for example. The mudflat fiddler crab, Uca, lives on beaches where tides rise and fall roughly every 12 hours. Researchers found that these crabs become more active and darken their shells just before each low tide, even when kept in a laboratory with no tidal cues. This timing helps them feed on exposed mud without being swept away. A second example involves the honeybee. Bees have a remarkable time-memory for flower nectar production. In experiments, bees returned to a specific patch of flowers at the exact time of day when nectar was most abundant, even if they were moved to a new location with different light conditions. This allows them to maximize foraging efficiency. So, biological clocks are not general but are specifically adapted to the predictable patterns in each animal's habitat.