Is there any differences between the terms Category, Rank and Taxon or they all are same?

I remember an explanation which goes on like this:

Category and Rank are the same and are the categories of taxonomic heirarchy whereas taxons are the organisms present in those.

Is this correct?

  • 1
    $\begingroup$ Maybe adding some example context would help answer. Anyway, a taxon is not an organism, but rather any level and grouping one can distinguiah, the last smallest one being a species (a group of individuals). Of the other two, no idea to be honest. $\endgroup$
    – Athe
    Aug 20, 2015 at 19:07

1 Answer 1


A taxon (plural taxa) is any taxonomic unit. For example, the class Mammalia is a taxon which includes all mammalian species. Similarly, a species is a taxon, Panthera tigris being the tiger. This taxon contains lower taxa, which are sub-species, such as Panthera tigris tigris (Bengal tiger) or Panthera tigris sumatrae (Sumatran tiger).

Rank is simply the level of a taxon in the taxonomic heirarchy. For example, the taxa Mammalia and Aves both have the same rank since they are both classes. Panthera tigris sumatrae is of a lower rank than Panthera tigris because the former is a sub-species and the latter a species. Use of the term rank is only truly meaningful when comparing two taxa.

Taxonomic category is usually – for better or worse – used interchangeably with the term taxonomic rank. A Dictionary of Biology (6 ed.) certainly indicates that the terms rank and category are equivalent. The major taxonomic categories are domain, kingdom, phylum, class, order, family, genus, and species. A category can contain one or more taxa.

Another example, to summarize:

  • Carnivora is a taxon, which contains many species including Vulpes vulpes (red fox)
  • Carnivora is in the category of order
  • Carnivora (order) is a higher rank than Vulpes vulpes (species)
  • $\begingroup$ Welcome to Bio. Great answer, but adding a reference or two would be appreciated. $\endgroup$
    – AliceD
    Sep 16, 2015 at 5:55
  • $\begingroup$ I am not sure if Reptilia is considered a taxon. It is most definitely not a clade. $\endgroup$
    Sep 16, 2015 at 16:59
  • $\begingroup$ @WYSIWYG Yes, it was a bad example - I've changed it $\endgroup$ Sep 16, 2015 at 17:03
  • $\begingroup$ @HarryVervet Please correct me if I am wrong -- you said "the taxa Mammalia and Aves both have the same rank since they are both classes"... which would that imply that class is the name of their shared rank, and thus kingdom, phylum, etc refer to taxonomy ranks, and are not taxons themselves $\endgroup$ Feb 15, 2016 at 18:20

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