Extinction and Endangered Species - Defining And Naming Life On Earth

Living organisms are named and categorized according to a taxonomy, a hierarchical system of order based on the natural relationships among all types of life. For example, Table 1.1 shows the taxonomic chart for blue whales, the largest creatures on Earth. Blue whales are described by eight taxonomic levels ending with "species." A species is a term assigned to a group of organisms that are considered capable of interbreeding with one another. There is another category called "subspecies," that ranks immediately below species. A subspecies (abbreviated ssp.) is a population of a particular geographical region that is genetically different from other populations of the same species, but can still interbreed with them.

Animals and plants are identified by their common names and by unique scientific names. Some organisms have more than one common name. The animal known as the mountain lion is also called a puma or a cougar. To avoid confusion, scientific bodies have established systems of nomenclature (naming) for animals and plants. These systems are based on the example set by Carolus Linnaeus (1707–78), a Swiss botanist who published classifications for thousands of plants and animals. Linnaeus popularized the use of a binary naming system in TABLE 1.1 Taxonomic chart for blue whales "The Chart Below Is a Sample Taxonomic Chart for Blue Whales," in Scientific Classification, U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Mammal Laboratory, March 3, 2004, http://nmml.afsc.noaa.gov/education/taxonomy.htm (accessed February 7, 2006)Which the first word names the genus of the organism. The genus, which identifies a group of closely related species, is followed by a specific epithet (a descriptive word or phrase) that differentiates one species from another. Linnaeus used Latin words in his nomenclature because Latin was the preferred language for scientific publications during the eighteenth century.

TABLE 1.1
Taxonomic chart for blue whales
Classification	Blue whale example	Explanation
SOURCE: "The Chart Below Is a Sample Taxonomic Chart for Blue Whales," in Scientific Classification, U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Mammal Laboratory, March 3, 2004, http://nmml.afsc.noaa.gov/education/taxonomy.htm (accessed February 7, 2006)
Kingdom	Animalia	Whales belong to the kingdom Animalia because whales, have many cells, ingest food, and are formed from a "blastula" (from a fertilized egg)
Phylum	Chordata	An animal from the phylum Chordata has a spinal cord and gill pouches.
Class	Mammalia	Whales and other mammals are warm blooded, have glands to provide milk for their off-spring, and have a four-chambered heart.
Order	Cetacea	Cetaceans are mammals live completely in the water.
[Suborder]	Mysticeti	Whales that belong to the suborder Mysticeti have baleen plates (big filters in their mouths) rather than teeth.
Family	Balaenidae	The family Balaenidae, also called rorqual whales. They have pleats around their throat that allow them to hold lots of water (which contains their food).
Genus	Balaenoptera	A genus is a group of species that are more closely related to one another than any group in the family. Balaenoptera refers to the genus.
Species	Musculus	A species is a grouping of individuals that interbreed successfully. The blue whale species name is musculus.

Since the time of Linnaeus many thousands of additional plants and animals have been discovered or intentionally bred. Modern convention dictates that the scientist who first describes an organism in a scholarly publication chooses the scientific name for that organism. The scientific name must be in Latin or contain words that have been "Latinized" (rendered to appear Latin). During the 1800s the American researcher Frank Higgins discovered a new species of mussel (clam) in the Mississippi River. He called it Higgins' Eye. The scientific name is Lampsilis higginsii. In this case the specific epithet reflects the common name of the organism, but it is not required to do; it can be any descriptive term.

Scientific names are either italicized or underlined in print to distinguish them from surrounding text. The genus is capitalized, while the specific epithet is not capitalized.

Subspecies are indicated in scientific nomenclature with an additional term. For example, the scientific name of the blue whale is Balaenoptera musculus. A subspecies, the pygmy blue whale, is called Balaenoptera musculus brevicauda. Genus reassignments are indicated with the "=" sign in a scientific name. When the royal snail was discovered in 1977 it was assigned to the genus Marstonia. Ten years later biologists decided the snail was more properly a member of the genus Pyrgulopsis. Thus, the scientific name of the royal snail is written as Pyrgulopsis (=Marstonia) ogmorhaphe. When the species is not known for an organism of known genus, the scientific name is written with sp. (indicating a single species) or spp. (indicating multiple species) as the specific epithet. The latter format is also used when referring to all species in a genus. For example, Pyrgulopsis spp., refers to all species within the genus Pyrgulopsis.

The rules governing scientific names for animals are overseen by the International Commission on Zoological Nomenclature, headquartered in London, England. The International Code of Botanical Nomenclature for plants is set by the International Botanical Congress (IBC), a meeting of botanists from around the world held every six years. The most recent IBC took place in Vienna, Austria, in 2005.