TOEFL Listening

🎧 Listening Transcript

Listen to part of a lecture in a biology class. The professor is discussing animal communication. Professor: Today we're going to talk about how animals communicate, and I want to focus on a specific example: the honeybee. You might know that honeybees perform a 'waggle dance' to tell other bees where to find food. But what's fascinating is the precision of this communication. The angle of the dance relative to the sun indicates the direction of the food source. The duration of the waggle run—that's the straight part of the dance—encodes the distance. Longer waggle runs mean the food is farther away. Now, here's a question: how do bees measure distance? It's not based on visual cues, because in experiments, bees that flew through a tunnel with patterned walls still reported distance correctly. Instead, research suggests they use what's called 'optic flow'—the apparent motion of objects in their visual field. When the tunnel walls were featureless, the bees overestimated the distance, because there was less optic flow. So, the bee's distance message is calibrated by visual feedback from the environment. This is a remarkable example of how an animal translates sensory information into an abstract symbolic signal.