托福口语 Task 4

Today we're going to talk about a fascinating adaptation in the animal kingdom called 'countershading.' Countershading is a type of camouflage where an animal's body is darker on the top and lighter on the bottom. This pattern helps animals blend into their environment because, in nature, light typically comes from above. So, when a predator looks down at a prey animal, the darker top blends with the darker ground or water below. When a predator looks up from below, the lighter belly blends with the bright sky or surface. Let me give you two examples. First, consider the great white shark. When seen from above, its dark gray back matches the dark ocean floor, making it hard to spot. When seen from below, its white belly blends with the bright sunlight filtering through the water surface. Second, think about a common bird, the penguin. From above, its black back blends with the dark ocean when it swims, hiding it from aerial predators like seagulls. From below, its white belly matches the light sky, hiding it from predators in the water, like seals. This adaptation increases their chances of survival.