I'm sorry, but you are very confused about biology.And when animals adapt, the adaptation is supposed to be permanant, its supposed to be improving to more conditions it faces, not simply suited to the condition its already in, that isn't improving, that is simply suiting the enviroment. The peppered moth should have the ability to change colour anyway at anytime to suit the enviroment if it is to adapt to improve its survival of the fittest. Fish have adapted to living on land have they? Is this really survival of the fittest, it isn't survival of the fittest anymore if he is in the see again and drownin. Evolution is flawed.
Adaptation takes place at several different levels. Within individuals, adaptation has two levels: developmental and immediate response. All offspring's bodies develop in response to environmental conditions. So, a child grows up in a high altitude environment, its body will be well suited to apoxia. A child grows up in poverty, it's going to be of smaller stature, have greater health problems and a shorter lifespan.
Immediate adaptive responses happen when you're faced with a challenge in the environment. So you go for a vacation in Peru to see Machu Pichu - suddenly, you're exposed to apoxic conditions. Your resting heart rate skyrockets, your breathing increases, blood pressure increases, mobility decreases. Over the course of three weeks, your red blood cell count will increase and your heart rate and breathing will return to near baseline.
Adaptive responses such as the above are the product of natural selection.