The field of Zoology has many different disciplines such as cell biology, physiology, marine biology, behaviour, and ecology, to name but a few. Zoologists can also study animals at the level of the cell, organ systems, whole animals, animal communities or whole ecosystems. Zoologists can consequently be divided and classified on the basis of their area of speciality. An anatomist, for example, studies the body organisation of animals, an ethologist studies animal behaviour, a physiologist studies how animals work and ecologists study how animals interact with their environment and other animals in it. Zoologists can also be divided on the basis of the animal groups on which they work; Entomologists study insects and Herpetologists, Ornithologists and Mammalogists work on snakes and amphibians, birds, and mammals, respectively.

Some Zoologists work in “pure” fields whereas others work in “applied” fields. Pure, basic or fundamental science can be interpreted as “science for its own sake” and is concerned with increasing our knowledge of how living things work. It provides the foundation for applied science. Applied science, as its name suggests, involves applying scientific knowledge to specific problems. For example, a Zoologist (who may be a mammalogist) may study a population of mice in the wild in order to understand how population numbers of mice fluctuate and what environmental factors are responsible for these fluctuations. This is pure research. He/she (or another Zoologist) may then apply this knowledge to control populations of mice that are causing an economic problem because they are eating stored grain. This is applied science. Many studies that fall into the applied sciences have major implications for man and the environment.