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 regulate an organism's activities in rhythm with environmental cycles, such as day and night. However, what's really interesting is how some animals can adjust these clocks to survive in extreme conditions. Let me give you two examples. First, consider the Arctic reindeer. In the far north, the sun doesn't set for months during summer, and it never rises during winter. You might think this would confuse their daily rhythms, but reindeer have actually evolved to abandon their 24-hour cycle altogether. During the summer, they feed continuously, whenever they're hungry, rather than following a strict day-night pattern. This helps them gain weight quickly for the long winter. Second, think about the Sahara Desert ant. This ant lives in one of the hottest places on Earth, where ground temperatures can exceed 50 degrees Celsius. To avoid the deadly heat, the ant doesn't rely on a simple daily clock. Instead, it uses an internal timer that resets each day based on when it leaves its nest. It forages for only about 10 minutes during the hottest part of the day, which is when its predators are also inactive. So, the key point is that biological clocks are not fixed; they can be remarkably flexible, allowing animals to adapt to their specific environments.