托福口语 Task 4

Today we're going to talk about a fascinating behavioral adaptation in animals called 'tonic immobility,' which is a state of temporary paralysis that some species enter when threatened. This isn't a conscious choice; it's an involuntary response triggered by extreme fear or physical restraint. The main point I want to emphasize is that tonic immobility serves a crucial survival function, but its effectiveness depends on the predator's hunting strategy. Let me give you two examples. First, consider the opossum. When faced with a dog or fox, an opossum will suddenly collapse, become stiff, and even emit a foul odor, mimicking death. Many predators, like foxes, prefer live prey and will lose interest in a seemingly dead animal, allowing the opossum to escape once the threat passes. Second, take the young chicks of certain ground-nesting birds, like the killdeer. If a hawk swoops down, a chick will freeze and press its body flat against the ground, blending in with its surroundings. This works because hawks rely on movement to spot prey from the air. Once the chick stops moving, the hawk can't see it and flies off. So, in both cases, the animal exploits the predator's specific sensory or behavioral biases to survive.