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Classification Biology


Classification in biology, is the identification, naming,
and grouping of organisms into a formal system. The vast
numbers of living forms are named and arranged in an
orderly manner so that biologists all over the world can be
sure they know the exact organism that is being examined
and discussed. Groups of organisms must be defined by the
selection of important characteristics, or shared traits,
that make the members of each group similar to one another
and unlike members of other groups. Modern classification
schemes also attempt to place groups into categories that
will reflect an understanding of the evolutionary processes
underlying the similarities and differences among
organisms. Such categories form a kind of pyramid, or
hierarchy, in which the different levels should represent
the different degrees of evolutionary relationship. The
hierarchy extends upward from several million species, each
made up of individual organisms that are closely related,
to a few kingdoms, each containing large assemblage Carolus
Linnaeus is probably the single most dominant figure in
systematic classification. Born in 1707, he had a mind that
was orderly to the extreme. People sent him plants from all
over the world, and he would devise a way to relate them.
At the age of thirty-two he was the author of fourteen
botanical works. His two most famous were Genera Plantarum,
developing an artificial sexual system, and Species
Plantarum, a famous work where he named and classified
every plant known to him, and for the first time gave each
plant a binomial. This binomial system was a vast
improvement over some of the old descriptive names for
plants used formerly. Before Linnaeus, Catnip was known as:
"Nepeta floribus interrupte spicatis pedunculatis" which is
a brief description of the plant. Linnaeus named it Nepeta
cataria--cataria meaning, "pertaining to cats". The
binomial nomenclature is not only more precise and
standardized; it also relates plants together, thus adding
much interest and information in the name. For instance,
Solanum relates the potato, the tomato and the Nightshade.
Binomial Classification Early on in naming species
taxonomists realized that there would have to be a
universal system of nomenclature. A system that was not
affected by language barriers, and would also classify the
millions of species throughout the world. Binomial
classification in its simplest form is a way of naming a
species by means of two names both in Latin. Latin was
originally used because it was the language of the founders
of the classification system, like Carolus Linnaeus, but it
continues to be used presently because it is a "dead
language". This means that it is no longer changing or
evolving, so it stays the same and can be used universally,
without confusion. Carolus Linnaeus (see Appendix A, Image
1) first introduced binomial classification, which is why
he is known as the father of the modern day classification
system. In Binomial classification the first name, which
begins with a capital letter is known as the Genus it is
always capitalized. The genus is a group of species more
closely related to one another than any other group of
species. The genus is more inclusive than the species
because it often contains many species. The second part of
the binomial represents the species itself and is always
printed with all letters in lower case. A species is a
group of individuals that are alike in many different ways.
Individuals are in the same species if they are: 1. Are
able to mate with those similar to themselves. 2. Produce
young that are themselves able to reproduce. As an example,
in the cat family, the genus Panthera is coupled with the
species leo to form Panthera leo, the Lion. Likewise,
Panthera is coupled with tigris, to form Panthera tigris
the Tiger. In simplified terns both the Lion(see Appendix
A, image 2) and Tiger share common traits and a common
genus - Panthera, whilst clearly remaining separate
species. To allow further subdivision, the prefixes sub-
and super- may be added to any category. In addition,
special intermediate categories-such as branch (between
kingdom and phylum), cohort (between class and order), and
tribe (between family and genus)-may be used in complex
classifications. Closely related species are a genus,
closely related genera (plural form of genus) are grouped
together in a family. Closely related families are grouped
into an order, and so on, into more inclusive categories,
or levels in the classification hierarchy. Taxonomic
Hierarchy Approximately one and a half million species have
been classified and there are estimates that over five
million species remain to be discovered. For biologists to
order this mass of information, a scientific system called
taxonomy was introduced. The basic idea is to group species
with similar characteristics together into families, and to
group the families together into broader groupings. To this
end, the taxonomic categories where devised, and they
create the taxonomic hierarchy. The hierarchy goes (with an
*Categories Example Kingdom Animalia Phylum (Plural =
Phyla) Cordata *In plants, this category is often called a
division* Class Mammalia Order Carnivora Family Canidae
Genus Canis Species Lupus (the Wolf)
Every species is in only one genus. Similarly, every genus
is in only one family, and so forth up the hierarchy. The
most inclusive category for classifying groups of similar
organisms is the Kingdom. It is argued exactly how many
Kingdoms there are though. Up until recently, only two
kingdoms were generally used, the plant and animal
kingdoms. Now however there are 5 established kingdoms and
one controversial unofficial kingdom.
The 5 kingdoms:
1. Kingdom Animalia (The Animal Kingdom) ex: Multi-cellular
motile organisms, which feed heterotrophically (Humans)
2. Kingdom Plantae (The Plant Kingdom) ex: Multi-cellular
organisms, which feed by photosynthesis (Tulips)
3. Kingdom Protista (The Protist Kingdom) ex: Protozoa and
single-celled algae
4. Kingdom Fungi (The Fungus Kingdom) ex: Yeast
5. Kingdom Monera (The Monera Kingdom) ex: Bacteria and
blue-green algae
Parallel to these Kingdoms, but not included, are the
Viruses. These are acellular entities with many of the
properties of other life forms, but are genetically and
structurally too dissimilar to the species categorized
above to fit into that scheme of taxonomy. Although this
system is complex and intricate at times, its universality
makes it a necessity. With out the system presently in use
the world would be years and years behind in their task to
name all of the living organisms on earth. This system is
great but it is always possible that some new finding could
cause the system to evolve to become more inclusive. This
system is by no means set in stone, and Linnaeus would
probably be astounded to see the way that it has evolved
since his original system
Appendix A
Carolus Linnaeus (Image 1) Panthera leo (Image 2)
Bibliography Berkely University.
www.ucmp.berkeley.edu/history/linnaeus.html/ Galbraith,
Don. Understanding Biology. John Wiley and Sons. Toronto.
1989, Microsoft. Encarta Encyclopedia 97. Microsoft
Corporation. 1997



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