การฟัง TOEFL

🎧 บทถอดเสียง

Narrator: Listen to part of a lecture in a biology class. Professor: So, we've been talking about animal communication, and today I want to focus on a fascinating example: the waggle dance of honeybees. When a forager bee finds a good nectar source, it returns to the hive and performs a series of movements. The dance consists of a figure-eight pattern, with a straight run in the middle. The angle of this straight run relative to vertical indicates the direction of the food source relative to the sun. For example, if the bee runs straight up, the food is directly toward the sun. If it runs at a 45-degree angle to the right, the food is 45 degrees to the right of the sun. The duration of the waggle run communicates distance. Longer runs mean the food is farther away. Interestingly, the bee also conveys the quality of the food by the intensity and repetition of the dance. A more vigorous dance signals a richer nectar source. This information allows other worker bees to locate the food without seeing it themselves. Now, what's remarkable is that this system is remarkably precise, but it's not without limitations. For instance, the dance is less accurate when the sun is obscured by clouds, and bees may then rely on other cues, like landmarks.