Animals adapt to many different things and for many different reasons. They mostly adapt to the environment or they adapt physically.
Animals can also adapt to different environments by natural selection, a process in which only the strongest animals can survive. Then, those who have survived can mate. This helps them adapt.
They would also adapt by having thick fur if they live in the arctic or having something to live without water for a longtime if they live in the desert.
They adapt to their environment with different characteristics like how the dog gets his winter coat in the wintertime and sheds the winter coat in summertime. The adaptations to a environment from an animal are not learned behaviors but they are inherited traits.