Classification

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Classification

• Chapter 18

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Why Classify?

• Think of all the things around you they can
  easily be put into organized groups, such as food
  types at a grocery store, clothing at a
  department store, books, CDs, etc.
• This organized grouping is called classification
• Purpose To find things, place things, identify
  things in an orderly way that makes sense
• Scientists call this taxonomy

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But how to make sense of it all Aristotle Cl
assified organisms based on where they lived
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Animals Air Land Water
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Does where an organism lives seem like a good
method for grouping? How about what they look
like (body structures, etc)? Carolus Linnaeus
more similar species share more traits and
characteristics Pg. 450 in textbookthe more
similar two organisms are, the more taxonomic
groups they share .
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Linnaeuss System

• A hierarchy
• Various levels each level is called taxon

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Scientific Names

• Common names are confusing language is an
  issue, several names can mean one animal puma,
  cougar, panther
• Latin, Greek is used
• First attempts used physical characteristics
  names too long, different scientists name things
  differently
• Binomial nomenclature Carolus Linnaeus, Swedish
  botanist two name system
• Homo sapiens
• First name is genus, second name is species
• Ursa martimus, Ursa arctos same genus or
  species???

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What problems do we now run into? Just because
two species look alike doesnt always mean that
theyre closely relatedthey may have just
evolved in very similar environments (think
convergent evolution and analogous
structures). Just because two things dont
look alike doesnt necessarily mean theyre NOT
closely related (bats and whales are both
mammalsthink divergent evolution and homologous
structures)
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So who gets to decide which structures are
important enough to use in classification and
which ones arent? When you did your Modes of
Transportation Taxonomy, did your group have the
same categories as everyone else? Which group did
it the right way? Horseshoe crabsCrustaceans??
? This was a great source of conflict among
scientists
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The Dichotomous Key

• A key used by scientists to classify organisms
• Uses a two-choice method to group organisms based
  upon their physical attributes
• Many field guides use this type of key
• Lets try one!!!

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Footwear

• a. Has laces go to 2
• b. No laces go to 3
• a. Sneaker? go to 4
• b. Shoe? go to 5
• Your footwear is a loafer or a slip-on
• a. Sneaker white? - go to 6
• b. Sneaker colored go to 7
• 5. a. Heels? - go to 8
• b. Flats? - go to 9
• Your footwear is a tennis sneaker
• Your footwear is a running sneaker
• Your footwear is a dress shoe
• Your footwear is a casual shoe