Throughout this course you will encounter the scientific names for organisms and the groups to which they belong. Each living organism has a two part or binomial name that consists of its genus and species, and the combination is unique to that organism. Both are underlined or italicized, and the genus name is capitalized, e.g. Homo sapiens or Homo sapiens. A genus can include many species, e.g. Homo erectus, Homo habilis. The same species name may be used in other genera, but the combinations of genus and species names must be unique. Once a genus name has been applied to a certain group of species, it cannot be used for any other groups of species unless they are added to its own group. The word species is both singular and plural; "specie" means currency (money). The system of binomial nomenclature was introduced by Carl Linnaeus (1707-1778) in Species plantarum (1753) and Systema naturae, 10th edition (1758), and these two works are used as the stating points for botanical and zoological nomenclature.

A classification is hierarchical with superkingdoms being the largest groups and subspecies the smallest. Each category may contain many subcategories of the next lower level. The following is a list of the categories used in this guide:

A mnemonic device for remembering the first letters of each word in the sequence from Kingdom to Species is: "King Philip came 'ome from Greece Saturday."

The purpose of a classification is to organize information. Closely related organisms usually share several derived or specialized characters. For example all members of the animal phylum Cnidaria share special stinging cells called cnidoblasts on their tentacles; they have two tissue layers, and a middle mostly non-cellular layer called mesoglea; they are radially symmetrical. Simply stating that a particular kind of animal is a member of the Cnidaria tells you a lot about that animal. The most informative classifications are based on the relationships or phylogeny of the included organisms.

The following classification of organisms includes mainly the groups that will be examined in laboratory (many categories are omitted).

DOMAIN ARCHAEA

DOMAIN BACTERIA

KINGDOM BACTERIA—autotrophs (Cyanobacteria) and heterotrophs

DOMAIN EUKARYA

KINGDOM PROTISTA—heterotrophs and photosynthetic autotrophs
   Phylum Euglenophyta—euglenoids
   Phylum Chrysophyta—diatoms
   Phylum Mastigophora—flagellated protozoans
   Phylum Sarcodina— amoebas, foraminifera, radiolaria
   Phylum Ciliophora—ciliated protozoans
   Phylum Oomycota—water molds

KINGDOM FUNGI—heterotrophs, mostly saprobes, some parasites
   Division Zygomycota—bread molds
   Division Ascomycota—sac fungi, yeasts
   Division Basidiomycota—mushrooms, etc.
   Division Deuteromycota—imperfect fungi (no sexual stage)—Penicillium
   Lichens—symbiotic association of a fungus with eukaryotic green alga
    or with prokaryotic cyanobacterium

KINGDOM PLANTAE—photosynthetic autotrophs
"Algae" [Starr & Taggart put the algae in the Kingdom Protista]
   Division Rhodophyta—red algae
   Division Phaeophyta—brown algae
   Division Chlorophyta—green algae
"land plants"
   Division Bryophyta—mosses and liverworts
   Division Pterophyta—ferns and relatives
   Division Coniferophyta—conifers (gymnosperms)
   Division Anthophyta—flowering plants (angiosperms)
      Class Dicotyledonae—e.g., geranium, carrot, maple
      Class Monocotyledonae—e.g., lily, grass, bamboo, palm

KINGDOM ANIMALIA—heterotrophs
"Invertebrates"
   Phylum Porifera—sponges
   Phylum Cnidaria
      Class Hydrozoa—hydras
      Class Scyphozoa—jellyfishes
      Class Anthozoa—sea anemones, corals
   Phylum Platyhelminthes—Flatworms
      Class Turbellaria—free living planarians
      Class Trematoda—parasitic flukes
      Class Cestoda—parasitic tapeworms
   Phylum Mollusca—mollusks
      Class Bivalvia (= Pelecypoda)—clams, scallops
      Class Gastropoda—snails, slugs
      Class Cephalopoda—squid, octopus, nautilus
   Phylum Annelida—segmented worms having a hydrostatic skeleton
      Class Oligochaeta—chiefly fresh water and land, earthworm
      Class Polychaeta—marine worms
      Class Hirudinea—leeches
   Phylum Arthropoda—exoskeleton and jointed legs
      Class Crustacea—shrimp, crayfish, crabs
      Class Insecta—butterflies, grasshoppers, beetles
      Class Chilopoda—centipedes
      Class Diplopoda—millipedes
      Class Arachnida—spiders, scorpions, ticks, mites
"Vertebrates" and their relatives
   Phylum Echinodermata—spiny-skinned, endoskeleton of calcareous plates
      Class Asteroidea—starfish
      Class Echinoidea—sea urchins, sand dollars
      Class Holothuroidea—sea cucumbers
   Phylum Chordata—notochord, pharyngeal gills, dorsal, hollow nerve cord
      Subphylum Urochordata—tunicates
      Subphylum Cephalochordata—amphioxus (lancelets)
      Subphylum Vertebrata—fish, amphibians, reptiles, mammals

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