CLASSIFICATION: The Order of Living Things

For centuries, scientists around the world have been exploring the natural world. These naturalists often describe plants and animal and assign them meaningful names. Until the middle 1770’s, there was no widely accepted method for naming organisms. So, different nationalities would often give different names to the same plant or animal. Not surprisingly, confusion would arise from these different names.

Carl von Linné

Carl Linnaeus (1707 – 1778), a Swedish botanist, understood there needed to be a way to name and order living things. So, he developed a system to give unique names to each plant and animal (those were the only types of organisms “known” at the time; fungi, bacteria, and alike were considered either plant or animal). His system is called “binomial nomenclature” because it uses two names to identify organisms. This binomial nomenclature system has been used to name every organism since.

In his system, Linnaeus gave every organism two specific names. He chose two names because there were not enough single names in any language for all the species. The first name is used to identify the organism’s genus (a group of organisms with the same characteristics). The second word is the specific epithet, which identifies the specific kind of organism. Since a specific epithet may be used for more than one species, both names (the genus and specific epithet) are used to form the “scientific name” which is unique for the organism.

Systema Naturae

Scientific names use words that have Latin or Greek roots, or modern words that have been “Latinized.” These words typically, but not always, describe the organism. Latin is the language of choice because it is considered a “dead language” which is not undergoing changes due to modern use.

In addition to using two names, the system has acquired other features. In order to separate the two words, the genus name is always capitalized while the specific epithet is lower case. In addition, to distinguish scientific names from common (or local) names, scientific names are either italicized or individually underlined. Also, when the scientific names of two organisms in the same genus are mentioned together, the genus name can be abbreviated by its first letter, after the first time its written out (see the example in the table for the Golden Eagle).

Bald Eagle

To see how this binomial nomenclature system works, let’s use the Bald Eagle (Haliaeetus leucocephalus). The genus name, Haliaeetus, comes from the root words: “hal” meaning “the sea” and “aetos” meaning “eagle.” So, the genus applies to the “sea eagles.” The specific epithet, leucocephalus, comes from the root words: “leuco” meaning “white” and “cephalus” meaning “head.” So, the scientific name of the bald eagle, Haliaeetus leucocephalus, means a white-headed sea eagle. It can be fascinating to discover the meanings of scientific names.

The Golden Eagle is the most wide-spread eagle in the world. Here is how its entire classification would look.

Golden Eagle Distribution