Our planet offers a wide variety of places for organisms to live.  Because of this, through all the history of Earth life had been developing according to these needs.  From unicellular organisms to the biggest multicellular organisms, every living thing must adapt, it is, to get used to the conditions of their environment.  An adaptation is a feature or a behavior that allows an organism to survive in its environment.  Adaptations are given by modifications on the DNA of the organism due to any change in the environment.  Sometimes, organisms adapt each other in a relation called symbiosis produced through a mechanism called coevolution.