托福口语 Task 4

Today we're going to talk about a fascinating concept in animal behavior called 'biological rhythms'—specifically, how some animals have internal clocks that help them survive in extreme environments. One main point is that these rhythms are not just responses to external changes but are internally driven, allowing animals to anticipate events. Let me give you two examples. First, consider the fiddler crab. These crabs live on tidal beaches, and their activity cycles—when they feed and when they hide—shift with the tides. Interestingly, even if you take a fiddler crab into a lab with constant conditions, it still becomes active at the exact times of low tide at its original beach. This shows an internal tidal rhythm. Second, think about the honeybee. Bees have a circadian rhythm that helps them know when flowers open, based on the time of day. Researchers trained bees to visit a feeder at a specific time, and even when kept in constant darkness with no time cues, they returned to the feeder at the same time each day. This demonstrates an internal daily clock. So, the main point is that biological rhythms are internally generated and help animals adapt to predictable environmental changes.