Classification System Notes

History of Classification

322-384 BC: Aristotle—Greek philosopher, one of the first to try to classify living things

  • grouped all living things as either plants or animals
    • Plants—divided into trees, shrubs, and herbs
    • Animals—divided as those in water, on land, or could fly
      • problems:
        • some could fit more than one category
          • (frogs are on land and in water);
        • some in the same category were not closely related
          • (fish, lobster live in water)

plant classes

 

1700s: Carl von Linne (or Carolius Linnaeus)—Swedish botanist (studied plants)

  • saw problems with Aristotle’s and tried to fix it
  • still classified everything as plant or animal
    • very little know about microscopic organisms yet
  • system had 5 taxonomic levels, with plants and animals as 2 kingdoms of life
    • gave everything a two-word name (including himself)

Binomial Nomenclature—process of assigning a 2 word name to all living things

  • (bi = 2; nomial = name; nomen = name; cloture = system à “2 name naming system”)

Scientific Names

  • Latin names used so scientists can communicate worldwide and be understood
  • don’t need to learn multiple names for the same organism
    • Example: Felis concolor = cougar, puma, mountain lion, catamount, panther
  • scientific name is composed of a genus (first) and species name (second)

Genus –group of several species that are closely related (2 with same genus name are closely related)

Species name—descriptive, so 2 can have the same species name and not be related

 

Writing scientific names

  • Genus is first, with the first letter capitalized (may be abbreviated to one letter)
  • species is second, with the first letter lowercase
  • entire name is underlined or italicized

                        Homo sapiens  or H. sapiens

 

Current Classification system

  • based on Linnaeus’ system; works because can be changed as needed
  • grown to include 8 taxonomic levels, including 3 domains and 6 kingdoms:
Levels Examples

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Eukarya

Animalia

Chordata (has backbone)

Mammalia (gives milk)

Primates (collar bones, grasping fingers)

Hominids (flat face, 3D vision)

Homo (upright, large brain)

Sapiens (high forehead, thin skull)

Can be difficult to tell differences by sight alone...