托福口语 Task 4

Today, we're going to discuss a fascinating phenomenon in animal behavior called 'biological clocks.' These are internal mechanisms that allow animals to anticipate regular changes in their environment, not just respond to them. Take the fiddler crab, for example. As the tide rises and falls, the crab's color changes rhythmically—it darkens at high tide and lightens at low tide. This happens even if the crab is kept in a lab with no tidal cues, showing that its internal clock is innate. The clock helps the crab avoid predators by matching its activity to the safest times. Another example is the honeybee. Bees have a remarkable ability to remember the location of a food source and the time of day it's available. In experiments, bees trained to visit a feeder at 10 a.m. will return at exactly 10 a.m. the next day, even if the feeder is moved or removed. This time-based memory allows bees to efficiently forage, minimizing wasted energy. So, biological clocks are not just automatic reactions; they are adaptive, allowing animals to prepare for predictable events, which greatly increases their survival.