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 look at how animals communicate, but not just through sounds or visual signals. I want to focus on chemical communication, specifically pheromones. Pheromones are chemical substances released by an animal that affect the behavior or physiology of another animal of the same species. For example, ants release pheromones to mark trails to food sources, and when other ants detect these chemicals, they follow the trail. This is a form of long-lasting communication, unlike a visual signal which disappears quickly. However, pheromones are not always permanent. In some species, like moths, females release a pheromone to attract males over long distances, but the signal is only effective for a short period because it disperses quickly in the air. So, the duration of the chemical signal depends on the environment and the type of pheromone. Some are volatile, meaning they evaporate quickly, while others are more stable and persist longer. Now, why is this distinction important? Well, it affects how we study animal behavior. For instance, if a pheromone is volatile, it's harder to track in the field because it vanishes fast. So researchers often need to use artificial pheromones in controlled experiments. Does anyone have a question?