Classification can be a tricky business. Problems arise when something can be classified
to greater detail or when an object or organism could belong to more than one category.
Biologists have faced these classification conundrums for centuries when trying to classify
organisms in one category or another. We will introduce you now to one of the most com-
mon classification schemes: the five-kingdom system of classification.Artificial classification systems, such as the grouping of vehicles into those that provide trans-
port on land/ water/ air etc., are based on arbitrary groupings and have little meaning. The
biological classification system, however, is based on research in biology, chemistry, genet-
ics, etc. It is a scientific method of classification that groups organisms that share common
features and is more universally accepted.It is always necessarily hierarchical where the important features inherited from a common
ancestor determine the group in which the organisms are placed. For example humans and
whales both feed their young on milk and it is a characteristic inherited from a common
ancestor which places them under the same classmammalseven though their habitats are
completely different.Each organism is grouped into one of five large groups orkingdoms, which are subdivided
into smaller groups calledphyla(singular: phylum) and then smaller and smaller groups with
other names.- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
Figure 10.1: Schematic diagram showing hierarchy or ranking scheme used by taxonomists.When trying to identify animals it is this hierarchy or ranking scheme that we follow whereby
we start by identifying the kingdom to which an organism belongs, then its phylum, class,
genus and so on. This is similar to explaining to a being from another planet how to find
your house. You would have to say Earth first, then Africa, then South Africa, then KZN, then
Durban, then the suburb, then the road name and finally the house number. He would have
to start searching in a big place and gradually work down to smaller places (or groupings).298 10.3. Classification schemes