What is classification?

Find out about animal classification, taxonomy and systematics.

The Australian Museum specialises in taxonomic and systematic research. Taxonomy and systematics comprise the describing, naming and classifying of plants and animals, and studying their origins and interrelationships. This type of research is essential for environmental assessments. It forms the basic building blocks of the study of nature, and is a key science on which many others depend.

Levels of classification

Taxonomists classify all organisms into a hierarchy, and give them standardized names, that are often Latin or Greek, or derived from other languages and even people's names. There are seven main levels of classification in the hierarchy. They are, from the most to the least inclusive:

  • kingdom
  • phylum (pl. phyla) for animals or division for algae, fungi and plants
  • class
  • order
  • family
  • genus (pl. genera)
  • species

There are several more levels of classification within this hierarchy that can further differentiate between groups of organisms, with some being specific to certain groups.


Ondine Evans , Web Researcher/Editor
Last Updated:

3 comments

Sascha Schulz - 3.07 PM, 20 July 2009
Hi Erik, great to see you on here! The class Osteichthyes aka "Bony Fishes" has (had) two sub-classes namely the Actinopterygii (Ray-finned Fishes) and the Sarcopterygii (Lobe-finned Fishes). The Actinopterygii includes most extant bony fish species, whereas the Sarcopterygii contains less than a dozen species of Lungfish and Coelacanths. Some variations of the classification system elevate the Osteichthyes to "Superclass", and the Actinopterygii and Sarcopterygii to class status, and that is what is being used here. The study of deep level phylogenetics has advanced considerably in recent years as genetic work has become more commonplace and I suspect we will see the classification "tree" evolve (ha!) a great deal over the years to come.
eschlogl - 4.07 PM, 18 July 2009
A question: I noticed that on this site what used to be known as "bony fishes" are now in the class Actinopterygii. Does that mean that the class Osteichthyes is no longer considered valid?

Report misuse