Essay/Term paper: Classification biology

Essay, term paper, research paper:  College Papers

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
example):

*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