Classification

1
Classification

• Chapter 18

2
Why Classify

• There are 2.5 million organisms with as many as
  20 million yet to be named.
• Scientists must use a classification system that
  names orders the organisms in a logical manner.
• There are two factors to a good classification
  system.
• Must have a universally accepted name.
• Place organisms in groups with real biological
  meaning.
• The groups are expected to share important
  traits.
• In the 1700s common names were replaced by Latin
  or ancient Greek names
• The names described the organisms were too
  long.
• This system was difficult to standardize.

3
Carolus Linnaeus

• Carolus Linnaeus developed Binominal
  Nomenclature.
• Every organism has a two part name.
• The first part is the genus it describes a
  small group to which the organism belongs.
• The second is the species usually describes a
  special trait.
• The genus is Capitalized and the species is lower
  case (usually in italics)
• There is a committee which oversees the naming
  process carefully selects a specimen.

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How Linnaeus Creates his System

• Linnaeus organized all the known existing
  organisms into binomial nomenclature.
• He grouped organisms by shared body structures
• The groups he called Taxa (taxon)
• The science of naming these groups is called
  taxonomy.
• Linnaeus created an order from smallest to
  largest.

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The Groups

• Listed from smallest to largest
• Species- shared traits but different biological
  units (may reproduce viable offspring)
• Genus- similar structures
• Family- groups of genus with some variation in
  structure.
• Order- several families make an order, still
  shared traits.
• Class- orders are placed in classes, I.e.
  mammalia
• Phylum- large group consisting of different
  animals yet share common characteristics
• Kingdom- Two giant Taxa separating plants and
  animals
• Read this section carefully (pay attention to the
  names)

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Classification of Ursus arctos
Black bear
Giant panda
Grizzly bear
Abert squirrel
Red fox
Coral snake
Sea star
KINGDOM Animalia
PHYLUM Chordata
CLASS Mammalia
ORDER Carnivora
FAMILY Ursidae
GENUS Ursus
SPECIES Ursus arctos
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Taxonomy and Evolutionary Relationships

• Phylogeny studies the evolutionary realtionships
• Species closely related are grouped together
  while organisms with analogous structures are
  placed in different groups.
• A Cladogram use derived characters to show
  evolutionary relationships.
• Biochemical Taxonomy
• The more similar the genes the more closely
  related the organisms. Molecular clocks show
  this
• Cytochrome C is a protein found in all organisms.
  The more mutations the more distant the
  relationship.

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Traditional Classification Versus Cladogram
Appendages
Conical Shells
Crustaceans
Gastropod
Crab
Crab
Limpet
Limpet
Barnacle
Barnacle
Molted exoskeleton
Segmentation
Tiny free-swimming larva
CLASSIFICATION BASED ON VISIBLE SIMILARITIES
CLADOGRAM
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The Six Kingdom System

• Monera has been split into Eubacteria
  Archaebacteria which are prokaryotes. Early
  forms lacked nuclei, mitochondria, chloroplast
  and reproduced by binary fission
• Protista are single celled eukaryotes with
  membrane bound organelles. They are divided into
  three categories.
• Fungi cells have no cellulose in the cell walls,
  they are heterotrophic, and may have many nuclei
  in the same cell.
• Plantae multicellular, autotrophic, cell walls
  contain cellulose.
• Animalia multicellular, cell membrane but no cell
  wall, heterotrophic, and very diverse kingdom.

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Three Domain System

• Domains are larger than Kingdoms
• Domain Bacteria are single celled prokaryotes
  with peptidoglycan very diverse.
• Domain Archaea live in extreme environments
  lack peptidoglycan
• Domain Eukarya is divided into four kingdoms
  Protista, Fungi, Plantea, Animalia

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Key Characteristics of Kingdoms and Domains
Classification of Living Things
DOMAIN KINGDOM CELL TYPE CELL
STRUCTURES NUMBER OF CELLS MODE OF
NUTRITION EXAMPLES
Bacteria Eubacteria Prokaryote Cell walls with
peptidoglycan Unicellular Autotroph or
heterotroph Streptococcus, Escherichia coli
Archaea Archaebacteria Prokaryote Cell walls
without peptidoglycan Unicellular Autotroph
or heterotroph Methanogens, halophiles
Protista Eukaryote Cell walls of cellulose in
some some have chloroplasts Most unicellular
some colonial some multicellular Autotroph or
heterotroph Amoeba, Paramecium, slime molds,
giant kelp
Fungi Eukaryote Cell walls of
chitin Most multicellular some
unicellular Heterotroph Mushrooms, yeasts
Plantae Eukaryote Cell walls of cellulose
chloroplasts Multicellular Autotroph Mos
ses, ferns, flowering plants
Animalia Eukaryote No cell walls or
chloroplasts Multicellular Heterotroph
Sponges, worms, insects, fishes, mammals
Eukarya
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Living Things
are characterized by
Important characteristics
which place them in
and differing
Domain Eukarya
Cell wall structures
such as
which is subdivided into
which place them in
which coincides with
which coincides with
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Cladogram of Six Kingdoms and Three Domains
DOMAIN ARCHAEA
DOMAIN EUKARYA
Kingdoms
Eubacteria Archaebacteria Protista Plantae Fungi A
nimalia
DOMAIN BACTERIA