托福听力

🎧 听力原文

Narrator: Listen to part of a lecture in a biology class. Professor: Today we’re going to talk about mimicry, but not the kind you might think of—like a butterfly looking like a leaf. We’re focusing on aggressive mimicry, where a predator or parasite imitates a harmless species to lure its prey. A classic example is the anglerfish. It has a fleshy growth on its head that looks like a small fish or worm. When a smaller fish approaches to eat it, the anglerfish strikes. But there’s an even more fascinating case: the bolas spider. Instead of spinning a typical web, it produces a single sticky thread with a drop of glue. Then it releases a chemical that mimics the pheromone of a female moth. Male moths, attracted to this scent, fly close, and the spider swings its thread to catch them. This strategy is highly efficient because the spider uses less energy than web-building spiders. However, it also has a risk: if the moth species changes its pheromone, the spider must adapt quickly or starve. So, aggressive mimicry shows how evolution fine-tunes both appearance and behavior for survival.