Dichotomous Keys

Coach E

Intro

Dichotomous Keys consists of eight sections: Domain, Kingdom, Phylum, Class, Order, Family, Genus and Species


The classification for human beings, for example, is Domain: Eukarya, Kingdom: Animalia, Phylum: Choradata, Class: Mammalia, Order: Primate, Family: Hominidae, Genus: Homo, Species: sapiens.

Domain and Kingdom

All organisms can be divided into three Domains: Bacteria, Archaea, and Eukarya. These three domains can be further divided into six smaller groups known as Kingdoms. All living organisms can be placed into one of these six kingdoms based upon such characteristics as the structure of their cells or how they get food.


The Domain Bacteria only has one kingdom, the Kingdom Bacteria. This is also the case for the Domain Archaea (Kingdom Archaea). The Domain Eukarya, on the other hand, consists of four kingdoms: Protista, Plantae, Fungi, and Animalia. Kingdom Protista consists of eukaryotic organisms that are primarily unicellular and other, simple multicellular relatives, such as slime mold or algae.


Eukaryotes that get their nutrients by decomposing organic matter, like mushrooms or mold, are classified in the Kingdom Fungi. Eukaryotes that are multicellular and make their own food, known as autotrophs, are classified in the Kingdom Plantae. This includes mosses, trees, and flowering plants.


The Kingdom Animalia consists of multicellular, heterotrophic eukaryotes. This group includes insects, reptiles, birds, and mammals. Scientists break these kingdoms down into smaller and smaller classification groups.

Phylum and Class

The definition of a phylum is a major category of living organisms, or a group of genetically related language families.


  1. An example of a phylum is Mollusca which means an invertebrate animal such as an octopus.


A class is: A group or set (of things or entities) with common characteristics, attributes, qualities or traits.

Order and Family

Genus and Species