Classification

The first rank in the classification system is called a kingdom. There are five kingdoms, based upon what an organism's cells are like:

  • animals (all multicellular animals)
  • plants (all green plants)
  • fungi (moulds, mushrooms, yeast)
  • prokaryotes (bacteria, blue-green algae)
  • protoctists (Amoeba, Paramecium).

There are several further ranks before we reach a particular species. In order, these are:

  • kingdom
  • phylum
  • class
  • order
  • family
  • genus
  • species

Difficulties with Classification

It can be difficult to classify a species e.g. we are Homo Sapiens

rankclassificationnotes
kingdomanimals 
phylumchordatesanimals with backbones
classmammalsanimals that are warm-blooded, have lungs and body hair, produce milk and give birth to live young
orderprimatesape-like animals
familyhominidshuman-like animals
genushomohumans
speciessapiensmodern humans

It can also be difficult to classify a certain organism. For example, the single-celled organism called Euglena has some confusing characteristics. It has:

  • chloroplasts, like a plant
  • no cell wall, like an animal
  • a flagellum to swim with, like some bacteria

A fifth kingdom, called the protoctists, was made for organisms like Euglena.

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