托福听力

🎧 听力原文

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, or the use of pheromones. These are chemical substances released by an animal that affect the behavior or physiology of another individual of the same species. Now, one classic example is the alarm pheromone in ants. When an ant is injured, it releases this chemical, which signals other ants to become aggressive and attack the threat. This is a fast and effective way to coordinate a colony defense. But pheromones aren't just for alarm. They also play a role in reproduction. For instance, female moths release a sex pheromone to attract males from a distance. The males have highly sensitive receptors that can detect even a few molecules of this chemical. Interestingly, the response to pheromones can be innate, meaning it's hardwired, not learned. So, unlike visual signals that might require experience to interpret, chemical signals often trigger an immediate, automatic response. This makes them particularly reliable for species that don't have long parental care or learning periods.