2.3.3. Classification and Identification

The need to classify living things gave rise to taxonomy – the science of grouping organisms on the basis of their similarities. One of the first taxonomic systems was proposed by the Greek philosopher Aristotle around 350 b.c. He divided living things into two groups, animals and plants. Aristotle subdivided animals on the basis of habitat, and behavior, and plants, on their size, and structure. Although Aristotle’s system contained many errors, it was used for more than 2000 years.

The system of Linnaeus

During the mid-1700, biologists began to explore the world to search for previousely unknown forms of life. As a result, thousands of newly discovered organisms were connected and described yearly. Although biologists used Aristotle’s system of taxonomy to classify these organisms, most reconized, that these system didn’t sufficiently explain the relationships between the organisms. In addition, the methods, naturalists used to name the newly discovered organisms, varied greatly. The use of many ineffective, and often contradictory systems made communication between biologist very difficult.

The way out of these difficulties was provided by the Swedish botanist named Carolus Linnaeus. Linnaeus developed a new classification system that revolutionized taxonomy. He suggested that organisms with similar structures should be placed in the same taxonomic group and suggested that this group was called a species. Linnaeus futher suggested that similar species were grouped into a larger category called a genus.

The scientific name

An organism is often known primarily by its common name – that is the name given it by people of an area. This practice has caused a great deal of confusion because one kind of organism may have many names. For example, in one region the mountain lion is called a puma, in another a cougar, in others a catamount or panther. Many organisms have also been misnamed, implying misleading relationships. Starfish, silverfish and jellyfish differ greatly from one another, and not one of them is a fish.

To avoid such problems, early taxonomists introduced the idea that each organism should be given a scientific name- that is, a short, standard name to be accepted by all scientists. Linnaeus suggested that the scientific name of an organism should consist of its genus name followed by its specific name. This practice is known as binomial nomenclature. Linnaeus continued the practice of using Latin, which was considered the “language of science” and was understood by all scientists of the time. An organism’s scientific name is written in a precise way. The genus name begins with a capital letter; the specific name with a lower-case letter. A scientific name is generally written in italic type or underlined. Felis concolor, or F. concolor for short, is the scientific name of the puma or mountain lion.

Many scientific names are descriptive. For example, the red maple is Acer rubrum, which means “red maple” in Latin. Sometimes a scientist names an organism after a scientist he or she admires. The genus Linnea, a herb of cold areas, was named in honor of Linnaeus. In many cases, a specific name describes where the organism lives, such as Darlingtonia californica, the carnivorous cobra lily of California.

In addition to giving an organism a scientific name, taxonomists may also cite the name of the person, who first described the organism. For example, the scientific name of the cobra lily is often written Darlingtonia californica Torr, to indicate that it was given its scientific name by John Torrey.