TOEFL Speaking Task 3

In biology, organisms often develop specialized adaptations to survive in their environments. One such adaptation is **camouflage**, which allows an animal to blend in with its surroundings, making it less visible to predators or prey. Camouflage can take many forms, including color matching, pattern disruption, or even changing appearance over time. This evolutionary trait increases an animal's chances of survival by reducing the likelihood of detection. Scientists study camouflage to understand how natural selection shapes physical traits in response to ecological pressures.

Professor: So, let's look at a real example of camouflage—the peppered moth. Before the Industrial Revolution in England, these moths mostly had light-colored wings with dark spots, which helped them blend in with the light-colored bark of trees and lichen. Birds, their main predators, couldn't easily spot them. However, during the Industrial Revolution, soot and pollution darkened the tree trunks. Suddenly, the light-colored moths stood out against the dark bark, and birds began eating them more easily. Over time, a dark-colored variant of the moth, which had always existed in small numbers, became more common because those moths were better hidden. The dark moths survived longer and reproduced more, passing on their genes. After pollution controls were introduced and tree bark became lighter again, the light-colored moths made a comeback. So, this shows how camouflage can change in response to environmental conditions.