TOEFL Listening

🎧 Listening Transcript

Narrator: Listen to part of a lecture in a biology class. The professor is discussing animal communication. Professor: So, we've talked about visual and auditory signals in animals. But today, let's consider chemical communication, specifically pheromones. Pheromones are chemical substances released by an animal that affect the behavior or physiology of others of the same species. They're particularly common in insects, like ants and moths, but also in mammals. For example, female moths release a sex pheromone that can attract males from kilometers away. Now, an interesting aspect is that pheromones are often species-specific. That means they don't usually trigger responses in different species. However, there are exceptions. Some predators have evolved to detect the pheromones of their prey, which gives them an advantage. Also, in social insects like bees, pheromones help maintain colony structure. They can signal alarm, mark trails, or indicate the presence of a queen. So, chemical communication is quite complex and vital. Now, let's think about the costs and benefits. Producing and detecting pheromones requires energy, but the advantage is that they work in the dark and can persist over time, unlike visual signals. Any questions so far?