Morphological adaptations are changes in an organism's morphology or external form so as to gain an advantage in surviving a particular environment or responding to a certain stimulus.
Some morphological adaptations are the spines of cacti which are modified leaves. Having spines instead of broadleaves greatly reduces water loss from the plant and also protects it's fleshy stem from potential predators. This is an example of a morphological adaptation towards the environment.
Another example is the adaptation developed by certain species of finch on their beaks which corresponds the type of food that these birds eat.