Taxonomic Classification System

• Taxonomic classification organizes different species of life on Earth.

Taxonomic Classification System

• It is ranked/hierarchical, becoming more specific until reaching the species level.
• Species are identified by binomial nomenclature, using genus and species.

History of Taxonomic Classification

• Carolus Linnaeus, a Swedish botanist, created the basis for the system in the 1700s.
• Linnaeus used morphological features, but today genetic information is used.
• As knowledge of life on Earth has grown, categories have been edited and added.

Taxonomic Levels

• Linnaeus proposed seven levels called "taxons"
• Kingdom is the broadest, species are the most specific
• Current system includes an additional taxon above kingdom, called domain

Modern Taxonomy Order

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

How to Remember Taxonomic Levels

• Use a mnemonic device to remember the taxonomic levels.
• Example: Dear King Philip Came Over For Good Soup

Domain

• It is the largest taxon.
• There are three main domains: Archaea, Bacteria, and Eukarya.
• Kingdom eubacteria is a sub-classification of domain bacteria so the terms bacteria and eubacteria are often used interchangeably.

Domain: Archaea

• These are prokaryotes (no nucleus or membrane-bound organelles).
• Possibly the oldest organisms on Earth.
• Can live in extreme environments (deep-sea vents, glaciers, salt flats).

Domain: Bacteria

• Also prokaryotes, but evolved later.
• Includes bacteria that cause human diseases like E. coli.

Domain: Eukarya

• Includes eukaryotic organisms (cells with a nucleus and membrane-bound organelles).
• Includes animals, plants, fungi, and protists.

Kingdom

• Used to be the highest level, now under domain.
• Each domain contains at least one kingdom.
• Archaea contain the kingdom Archaebacteria; bacteria contain the kingdom Eubacteria.

Domain Eukarya: Kingdoms

• Plantae: plants (stationary, photosynthetic).
• Animalia: animals (motile, eat for energy).
• Fungi: fungi (mushrooms, yeast, molds).
• Protista: diverse eukaryotes that don't fit in other kingdoms.

Phylum

• More specific than kingdom.
• Each kingdom contains many phyla.
• Examples from Animalia: Porifera, Cnidaria, Platyhelminthes, Annelida, Molluska, Arthropoda, Chordata.

Animalia Phylum Examples

• Porifera: sea sponges (mostly sessile).
• Cnidaria: jellyfish and hydras.
• Platyhelminthes: flatworms.
• Annelida: earthworms.
• Molluska: marine mollusks (octopuses, squids), bivalves, snails, slugs.
• Arthropoda: largest phylum of animals (insects).
• Chordata: organisms with a backbone (humans).

Class

• More specific than phylum.
• Examples from Chordata: Myxini, Hyperoartia, Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, Mammalia

Chordata Class Examples

• Myxini: hagfish
• Hyperaortia: lampreys
• Chondrichthyes: cartilaginous fish (sharks, rays)
• Osteichthyes: bony fish
• Amphibia: amphibians
• Reptilia: reptiles
• Aves: birds
• Mammalia: mammals (humans)

Order

• More specific than class.
• Example from Mammalia: Artiodactyla, Carnivora, Cetacea, Chiroptera, Dermoptera...

Mammalia Order Examples

• Artiodactyla: even-toed, hooved mammals
• Carnivora: meat-eating mammals
• Cetacea: whales and porpoises
• Chiroptera: bats
• Dermoptera: flying lemurs
• Edentata: toothless mammals
• Hyracoidae: hyrax rodents
• Insectivora: insect-eating mammals
• Lagomorpha: pikas, rabbits, hares
• Marsupialia: pouched mammals
• Monotremata: egg-laying mammals
• Perissodactyla: odd-toed hoofed mammals
• Pholidota: pangolins
• Pinnipedia: seals and walruses
• Primates: primates (humans)
• Proboscidea: elephants
• Rodentia: gnawing rodent mammals
• Sirenia: dugongs and manatees
• Tubulidentata: aardvarks.

Family

• More specific than order.
• Example from Carnivora: Canidae, Felidae, Ursidae, Procyonidae, Mustelidae...

Carnivora Family Examples

• Canidae: dogs
• Felidae: cats
• Ursidae: bears
• Procyonidae: raccoons
• Mustelidae: weasels, otters, badgers
• Mephitidae: skunks
• Herpestidae: mongooses
• Viverridae: civets, genets
• Hyaenidae: hyenas
• Otariidae: sea lions, fur seals
• Phocidae: true seals
• Odobenidae: walruses

Genus

• More specific than family.
• Part of binomial nomenclature.
• Example from Felidae: Felis, Otocolobus, Lynx, Caracal, Prionailurus, Leopardus, Puma, Neofelis, Panthera, Acinonyx

Species

• Most specific taxon.
• Second part of binomial nomenclature.
• Example from Panthera: P. uncia (Snow leopard), P. tigris (Tiger), P. pardus (Leopard), P. onca (Jaguar), P. leo (Lions)

Intermediate Levels

• Organisms don't always fit neatly into the eight categories.
• Use prefixes like supra-, inter-, infra-, and sub- to create intermediate levels.