托福口语 Task 4

Today, we're going to talk about a fascinating concept in animal behavior called 'sensory exploitation.' This is when a species evolves a trait that exploits an existing sensory bias in another species, often to its own advantage. The main point is that these traits aren't random; they tap into pre-existing preferences or sensitivities. Let me give you two examples. First, consider the male túngara frog. Females are naturally attracted to a 'whine' sound, which is a basic mating call. However, males add a 'chuck' at the end, and females strongly prefer calls with the chuck. This isn't because the chuck signals better genes—it's because the female's auditory system is already sensitive to low-frequency sounds, which the chuck provides. Second, think about the water mite, a tiny aquatic predator. Its larvae attach to insects that live near water. Interestingly, the larvae are attracted to water surface vibrations, which mimic the vibrations of their prey. This vibration sensitivity existed in the larvae before they ever encountered these insects, so the behavior exploited that pre-existing sensitivity to find hosts. So, in both cases, the traits evolved because they capitalized on existing sensory systems, not because they created new ones.