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Classification of Living Things
Taxonomy
Taxonomy
• Definition:– The branch of biology that deals with the
classification and naming of living things
Early Attempts at Classification• Aristotle
– animals– based groupings on habitats
• air-dwellers, land-dwellers, water-dwellers
• Theophrastus– plants– groupings on stem structure
• herbs (soft stems), shrubs (several woody stems), trees (one woody stem)
• Exploration & Microscopes made these two methods obsolete!
Early Attempts at Classification
• John Ray– advanced classification via plant studies– first to use term species
• Carolus Linnaeus– father of modern taxonomy– developed hierarchy of classification based
upon structural similarities– methods are still in use today
Classification Categories• Animal Taxonomy
– Kings Play Chess On Fine Green Silk• Kingdom• Phylum• Class• Order• Family • Genus • Species
• Plant Taxonomy– Division replaces Phylum
Binomial Nomenclature• Definition: a system for naming organisms based
upon two words• Naming of organisms used to be extremely confusing
– many organisms had multiple, multiple names
• Linnaeus “streamlines” by giving each organism a Genus and species name– i.e., Homo sapiens
• Eliminates the confusion of so-called “common naming”
Modern Taxonomy• Theory of Evolution serves as the basis for
modern taxonomic methods– Species: group of like individuals who can breed with
each other and produce fertile offspring• species separated for periods of time become different
species base upon mutations
• Phylogeny– evolutionary history of a species or a group of
organisms
– similar to a family tree
Human Phylogenic
Tree
Another Human
Phylogenic Tree
What Things Do We Use to Classify?• Structural Information
– skeletal, leaves, etc.
• Biochemical Information– DNA, RNA, protein structure, etc.
• Cytological Information– cell structure, chromosome number, etc.
• Embryological Information– structure in early stages of develpment
• Behavior Information– mating calls in crickets, etc.
What are the Kingdoms?
• “Old School” (Kingdoms)
– Monera
– Protista
– Fungi
– Plantae
– Animalia
• “New School” (Domains)– Archaebacteria– Eubacteria– Eukaryote
• Protista• Fungi• Plantae• Animalia
Archaebacteria
• Live in hostile environments
• Most in oxygen-free environments
• Unicellular & prokaryotic
• Examples– Methanogens– Halophiles– Thermoacidophiles
Eubacteria
• Make up the majority of modern bacteria• Most are unicellular
– chains or colonies
• Prokaryotic• Most heterotrophic• Disease-causing • Cyanobacteria
Protista
• Most are unicellular– some colonial and
multicellular
• Eukaryotic
• Heterotrophic are protozoa
• Phototrophic are algae
Fungi• Includes molds, yeasts, mushrooms, etc.• Function as either parasites or decomposers of
dead matter• Most multicellular, some unicellular• Eukaryotic• Have cell walls but of different chemical
structure than plants (chitin v. cellulose)• Cannot photosynthesize• Eat like flies!
Various Fungi
Plantae• Include mosses, ferns, liverworts, and seed
plants
• All have cell walls as part of cell structure
• Most all are photosynthetic
Animalia
• More species in this kingdom than all others
• All are multicellular with a higher level of organization
Animal Phyla• Porifera• Cnidaria• Platyhelminthes• Nematoda• Annelida• Mollusca• Arthropoda• Echinodermata• Chordata
Porifera
• Includes the sponges
Cnidaria
• Includes two body forms,:– polyp – medussa
Platyhelminthes
• Flatworms
Nematoda
• The Roundworms
Annelida
• Segmented worms
Mollusca• Mollusks
– clams, snails slugs
Arthropoda
• Segmented bodies, exoskeletons– crustaceans– centipedes– millipedes– spiders– insects
Echinodermata
• Starfish
• Sea urchins and cucumbers
• Sand dollars
Chordata
• Spinal cord
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