托福口语 Task 4

Today we're going to talk about a phenomenon in animal behavior called 'sensory exploitation.' This is when a species evolves a trait that exploits an existing sensory bias in another species, often for mating or predation. The main point is that these traits are not arbitrary; they tap into pre-existing preferences in the receiver. Let me give you two examples. First, consider the water mite, a tiny aquatic arachnid. Its larvae attach to copepods as parasites. But interestingly, the larvae wriggle in a way that mimics the movement of a copepod's preferred prey—a small crustacean called a Daphnia. Copepods already have a strong visual response to Daphnia's jerky swimming, so when they see the mite larvae, they approach and try to eat them, but the larvae quickly attach to the copepod's body instead. Second, think about the male túngara frog. Females have a pre-existing attraction to a particular low-frequency 'chuck' sound, which they use to locate water sources. Males exploit this by adding a 'chuck' to their calls, making them more attractive to females. So in both cases, the exploiting species uses a signal that matches an existing bias in the receiver, increasing their reproductive success.