Answer :
The most basic and perhaps powerful example is the fin-tailed fish, whose powerful tail is crucial for mobility, agility, and speed underwater. These adaptations have been underway for millions of years.
Some adaptations are purely physical. Fish have fins to help them swim and gills that let them breathe underwater. Without those two special traits, they would have a very hard time surviving in their watery environment. Animals also adapt through certain behaviors. When threatened, a porcupine extends its quills, making it very hard for a fox to eat them.