About Classification - How it Works
Living things (organisms) are broken down into groups with similar traits. This is
called, Biological classification. Biological classification begins with big, general groups
and gets smaller and more specific as they are broken down further. There are eight levels
at this time*:
Domain (Super-Kingdom)
Kingdom
Phylum
Class
Order
Family
Genus
Species
The DOMAIN is the highest ranking of Biological classification at this time* and includes 3
Domains: Archaea, Eubacteria and Eukaryota. We belong to the Domain Eukaryota –
which includes organisms with cells that contain a nucleus.
Next comes KINGDOM. For many years there were 5 Kingdoms: Animalia, Plantae, Fungi,
Protista, and Monera (you will still see these in most printed books). However, with the
adoption of the Domain Level the present 4 Kingdoms are as follows: Animalia, Plantae,
Fungi, Protista. (Protista, which includes plant-like algae, animal-like protozoans and
fungi-like slime molds may well be broken up into different groups in years to come.)
Next come the PHYLA (plural of phylum). The Kingdom Animalia currently has 9 Phyla:
• Chordata (Chordates – mammals, reptiles, birds, amphibians, etc):
• Mollusca (Mollusks – snails, octopus, & clams),
• Porifera (Sponges),
• Cnidaria (Corals & Jellyfish),
• Platyhelminthes (Flatworms),
• Nematoda (Roundworms),
• Annelida (Segmented Worms – earthworms & leeches),
• Arthropoda (Arthropods – insects, spiders, crabs, centipedes & millipedes),
• Echinodermata (Echinoderms – starfish, sea urchins, & sea cucumbers)
Next comes CLASS. The Phylum Chordata is made up of many Classes.
• Mammalia (Mammals)
• Amphibia (Amphibians)
• Aves (Birds)
• Osteichthyes (Fish) or Actinopterygii (ray-finned fish)
• Reptilia (Reptiles)
• Chondrichthyes (Sharks & Rays)
The Class Mammalia is broken down into 2 subclasses:
• Prototheria (monotrenes – like duck billed platypus)
• Theria
Then Theria has 2 infraclasses:
• Eutheria (placental mammals like us)
• Metatheria (marsupial mammals like kangaroos and koalas)
Next comes ORDER. Eutheria (placental mammals) includes the ORDERS:
• Carnivora (meat-eaters)
• Cetacea (whales and purpoises)
• Edentata or Xenarthra (toothless mammals)
• Tubulidentata (aardvarks)
• Hyracoidae (hyraxes, dassies)
• Lagomorpha (pikas, hares, and rabbits)
• Artiodactyla (even-toed hoofed animals)
• Perissodactyla (odd-toed hoofed animals)
• Chiroptera (bats)
• Dermoptera (colugos or flying lemurs)
• Pholidata (pangolins)
• Sirenia (dugongs and manatees)
• Proboscidea (elephants)
• Rodentia (gnawing mammals)
• Primates (humans, apes, lemurs and monkeys)
Next comes FAMILY. The Order Primates is made up of many Families. (We are included in
the Family Hominidae (human beings). There are also the families:
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Hominidae (human beings)
Tupalidae (tree shrew)
Lemuridae (lemurs)
Daubentonlidae (aye-ayes)
Lorisidae (lorises, pottos)
Tarsiidae (tarsiers)
Callitrichidae (marmosets)
Cebidae (New World monkeys)
Cercopithecidae (baboons, Old World monkeys)
Hylobatidae (gibbons)
Pongidae (gorillas, chimpanzees, orangutans)
Next comes GENUS. The Family Hominidae was once made up of many genera. We are
included in the genus Hominidae (human beings). All the other genera in the Family
Hominidae are extinct.
Lastly comes SPECIES. As the only living organism living in the genus Homo, our one
species is sapiens.
Organisms are called by their genus and species (species is always lower case), so we
are Homo sapiens.
A helpful way to remember the order of Biological classification is:
Dear > King > Phillip > Came > Over > From > Germany > Saturday
Domain > Kingdom > Phylum > Class > Order > Family > Genus > Species