Classifying Organisms
Importance of Taxonomy
• Taxonomy – the science of classifying organisms on the basis of shared characteristics
• Universal classification system helps scientists
• Store and retrieve information about organisms
• Communicate about organisms
Linnaeus
• Carolus Linnaeus developed current classification system
• Scientific name – the universally accepted name of a species, includes genus and specific name
• Binomial nomenclature – a method for naming species using two parts, genus and species
• First name is capitalized “genus”
• Second name is lowercase “specific name”
• Both underlined/italics
• Ex) Puma concolor (mountain lion)
• Seven level classification system:
• Kingdom, phylum, class, order,
family, genus, species
• Ex) Mountain lion classification:
• Kingdom Animalia
• Phylum Chordata
• Class Mammalia
• Order Carnivora
• Family Felidiae
• Genus Puma
• Species Puma concolor
Biology 14.2 – Classifying Organisms
Classifying Organisms
Classifying Organisms
• To classify an organism:
• Step 1 | Compare the
characteristics of each
taxonomic group with
characteristics of the
organism
• Step 2 | Use process of
elimination to determine the
best group
Kingdom
Archaea
Bacteria
Protista
Fungi
Plantae
Animalia
Major Characteristics
Prokaryotes, cell wall, may live in extreme
environments, unicellular, autotrophs or
heterotrophs
Prokaryotes, cell wall made of
peptidoglycan, unicellular, autotrophs or
heterotrophs
Eukaryotes, unicellular or multicellular,
autotrophs or heterotrophs, some have
cell wall, many are microscopic
Eukaryotes, most are multicellular, cell
wall made of chitin, absorb nutrients
through cell wall, immobile
Eukaryotes, most are multicellular, cell
walls composed of cellulose,
photosynthetic, autotrophs
Eukaryotes, multicellular, heterotrophs,
most are motile
Examples
Methane-producing
archaea, thermophiles
E. coli, salmonella
Algae, paramecia,
euglena, diatoms
Mushrooms, molds,
yeasts
Ferns, mosses, conifers,
flowering plants
Mammals, birds, insects,
worms, sponges
Dichotomous Keys
• Dichotomous key – a tool used to systematically identify and
classify organisms based on characteristics
• Allows systematic identification of organisms
• Step 1 | Determine which of the two options for
step one on the key is true
• Step 2 | Determine which step to go to next based
on the correct option
• Step 3 | Continue through the key until you have
an identification
Biology 14.2 – Classifying Organisms