In the living world, resources such as food and space are limited. As a result, survival is a constant struggle. Through evolution, animals have developed a range of adaptations that give them the best chances of success.
The most obvious of these adaptations are physical ones that affect the shape or structure of an animal's body. Equally important, although often less conspicuous, are adaptations that affect behavior and body processes. Together, these different adaptations allow each species to pursue a distinctive way of life.