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Biology LibreTexts

1: Taxonomy

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  • Introduction

    Because the diversity of life on Earth is so vast, biologists use a general system of classification and naming organisms (taxonomy) to track and organize species based on evolutionary relatedness. The broadest taxon is the domain; organisms belong to one of the three domains (Bacteria, Archaea, and Eukarya). Within the domains are increasingly specific taxa, usually following the order in the table below.

    The scientific name of an organism is given using binomial nomenclature; the genus and species of an organism give its specific scientific name. These names are usually derived from Greek or Latin, and therefore must be italicized when written. The genus is to be capitalized and the species is lower case. For example, the scientific name of a common wombat (top) is Vombatus ursinus.

    Let us compare the wombat to a similar species, a quokka (bottom).

      Wombat Quokka
    Domain Eukarya Eukarya
    Kingdom Animalia Animalia
    Phylum Chordata Chordata
    Class Mammalia (Marsupialia) Mammalia (Marsupialia)
    Order Diprotodontia Diprotodontia
    Family Vombatidae Macropodidae
    Genus Vombatus Setonix
    Species ursinus brachyurus

    3.png                                                          Screen Shot 2019-01-01 at 7.36.47 PM.png

    Figure \(\PageIndex{1}\) "Vombatus ursinus -Maria Island National Park"                        Figure \(\PageIndex{2}\) "Quokka” by the Hotel Rottnest, WA, Rottnest

                                                  by JJHarrison ( - Own work.                            Island" by Vicsandtheworld - Own work.

                                                  Licensed under CC BY-SA 3.0 via Wikimedia Commons                              Licensed under CC BY-SA 3.0 via Wikimedia Commons

    Note that both animals differ only when we reach the family level. If you knew that a kangaroo was in the same family as a quokka, would you assume the quokka was more closely related to a kangaroo or a wombat?

    Scientific names might seem confusing, but are useful for several reasons. Common names tend to vary according to region (crawfish, crayfish, mudbug, crawdad), but the scientific name is always the same.


    1. Llamas, alpacas, and camels are all in the same family: Camelidae. Therefore, it is reasonable to assume that these animals will also be in the same...

    2. The scientific name of the brown-throated three-toed sloth is named Bradypus variegatus. What is the genus of the organism? The species?