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CLASSIFICATION OF LIFE

Introduction
Taxonomic Order of Life
Taxonomy Books
Classification of Life

Kingdom Monera
Kingdom Protoctista
Kingdom Animalia
Kingdom Fungi
Kingdom Plants

Definition of the Taxonomic Order


The Taxonomic Hierarchy

This page provides you with each level of the taxonomic hierarchy and also gives a specific example to demonstrate how it works. Below the table, some of the taxonomic levels are given a commentary.

RANK Example
KINGDOM Animalia
PHYLUM Mollusca
CLASS Gastropoda
ORDER Caenogastropoda   
SUBORDER Neotaenioglossa
INFRAORDER Discopoda
SUPERFAMILY Tonnacea
FAMILY Ranellidae
SUBFAMILY Charoniinae
TRIBE Charoniini
GENUS Charonia
SUBGENUS Charonia
SPECIES tritonis
SUBSPECIES variegata
Source:

Rosenberg G, 'The Encyclopedia of Seashells', page 14, The Five Mile Press Pty Ltd, 1992, New York, NY, ISBN: 0867884819

In some ways it is difficult to visualise what each name means in the ranking of life. Simple word descriptions cannot portray their meanings anywhere near as well as illustrated groupings of creatures.

Even biological dictionaries will say things like: a superfamily is 'a taxon above a family and below an order'. So what does that tell you? Only its positioning in the hierarchy, but nothing about what logical groupings of creatures are to be placed in such a taxon.

Hence, a simple diagram picturing the types of creatures in a taxon makes it much easier to comprehend what the taxon embraces. Yet even without pictures, there are common words that mean something to most of us.


The major taxonomic groups can be described with words as follows:

Kingdom

This is a grouping of creatures that most people easily identify with. It groups creatures into plants, animals, bacteria, fungi and 'the rest' (ie, protoctista). Such descriptions divide all life forms into the largest taxonomic groups.


Phylum

Even a phylum can be described and it is still a major grouping of organisms. Words can put animals into easily pictured groups by the phylum taxon. Some descriptions of phylum include:

  • Molluscs (snails)
  • Chordates (mammals, birds, reptiles etc)
  • Cnidaria (jellyfish, corals)
  • Arthropoda (crustaceans, insects)

Class

This is also a high level grouping and is very familiar to most people, expressed in the following words: (All the classes below are in the phylum chordates)

  • Sharks
  • Bony fish
  • Amphibians
  • Birds
  • Reptiles
  • Mammals

Order

At this level, things start getting more detailed. In some classes the names of each order might not mean much to the average person. Yet, in the class insecta, there are words that have immediate pictures in most people's minds. The common name of the order is used in everyday language. For the insecta class the following orders will be familiar:

  • Dragonfliesdamsel fliesies
  • Butterflies & moths
  • Cockroaches
  • Beetles
  • Fleas
  • Flies
  • Termites

Family

Once you get to the family level, the detail becomes more familiar to people who have specific interests in nature and particular groups of creatures. For them, a family name has an instant meaning but for most of us, those names may not have a connotative picture. However, in the phylum mollusca, there are still family groups that have general familiarity at the family level. Some of these families are:

  • Conidae (cone shells)
  • Cypraeidae (cowrie shells)
  • Haliotidae (abalone shells)
  • Veneridae (venus clams)

Genus

This is the second-lowest major taxonomic grouping and at this level it takes a lot more knowledge of taxonomy to recognise what such names refer to. In the family Trochidae (of the phylum mollusca - shells, snails), some genus names are:

  • Cantharidus
  • Calliostoma
  • Clanculus
  • Phasianotrochus

Definition of a Species

This is not only the lowest significant taxon in the hierarchy, but also the most detailed. Ironically, the identity of creatures at this level is very clear to most people. Certain species of animals and plants are so well known and so often seen, that they are instantly recognisable. Even if people don't know their scientific names or are unfamiliar with common names, the concept of a well known species is easy to picture.



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