The Key to Classifying

We know that organisms are classified using the Linneaen taxonomic system, and they are named using binomial nomenclature. However, what do we do when we encounter an unknown organism? How can we name an organism found in the wild?

A dichotomous key is a tool used to identify organisms in a systematic way. It can be used to identify organisms parting from a certain taxonomic level. These keys are organized in such a way that the user has to make certain choices according to certain characteristics of the organism. Each step of the dichotomous key offers two choices (thus the name; dichotomous means: divided in two parts) until it points to a specific organism that has all the characteristics previously chosen.

Dichotomous keys are useful for identifying organisms in the field, or even in the lab when there is no other information available about the organism. Keys make come in diagram or in written form.

Here are two examples:

MLA: McGraw Hill. "Taxonomic Classification and Phylogenetic Trees." McGraw Hill Higher Education. The McGraw-Hill Companies, 2001. Web. 12 Aug 2010. .

Species Classification

There are so many different species on the planet that it's difficult to keep track of all of them. Scientists needed to find a way to classify each of them, and so taxonomy emerged.
Taxonomy is the science of identifying, describing, naming, and classifying living things. There are various ways of classifying organisms, but scientists currently rely on the Linnaean taxonomic system, created by Carl Linnaeus, a swedish biologist.

The Linnaean taxonomic system divides organisms into 7 major taxonomic levels called taxa: Kingdom, Phylum, Class, Order, Family, Genus, Species. However, there may be subdivisions like: subclass, suborder, etc. Each taxon becomes more specific as you move down the hierarchy of taxa. For example, many organisms may belong to the same kingdom, but not as many belong to the same phylum. Also, one is able to appreciate relationships between organisms using the taxonomic classification of each. Two species that share the same Order and Family are more closely related than two that only belong to the same order.

However, when naming an organism a binomial nomenclature. This means that when referring scientifically to a certain organism, one simply has to name the genus and species. For example, one would not write Atlantic salmon in a research paper, but would write Salmo salar.


MLA: Nixon, Joshua. "Scientific Names." Taxonomy. Michigan State University, n.d. Web. 12 Aug 2010. .