Classification in biology, is the identification, naming, and groupingof organisms into a formal system. The vast numbers of living forms arenamed and arranged in an orderly manner so that biologists all over theworld can be sure they know the exact organism that is being examinedand discussed. Groups of organisms must be defined by the selection ofimportant characteristics, or shared traits, that make the members ofeach group similar to one another and unlike members of other groups. Modern classification schemes also attempt to place groups intocategories that will reflect an understanding of the evolutionaryprocesses underlying the similarities and differences among organisms. Such categories form a kind of pyramid, or hierarchy, in which thedifferent levels should represent the different degrees of evolutionaryrelationship.
The hierarchy extends upward from several million species,each made up of individual organisms that are closely related, to a fewkingdoms, each containing large assemblages of organisms, many of whichare only distantly related. Carolus Linnaeus is probably the single most dominant figure insystematic classification. Born in 1707, he had a mind that was orderlyto the extreme. People sent him plants from all over the world, and hewould devise a way to relate them. At the age of thirty-two he was theauthor of fourteen botanical works.
His two most famous were GeneraPlantarum, developing an artificial sexual system, and SpeciesPlantarum, a famous work where he named and classified every plant knownto him, and for the first time gave each plant a binomial. This binomial system was a vast improvement over some of the olddescriptive names for plants used formerly. Before Linnaeus, Catnip wasknown as: “Nepeta floribus interrupte spicatis pedunculatis” which is abrief description of the plant. Linnaeus named it Nepetacataria–cataria meaning, “pertaining to cats”. The binomialnomenclature is not only more precise and standardized; it also relatesplants together, thus adding much interest and information in the name. For instance, Solanum relates the potato, the tomato and the Nightshade.
Binomial ClassificationEarly on in naming species taxonomists realized that there would have tobe a universal system of nomenclature. A system that was not affected bylanguage barriers, and would also classify the millions of speciesthroughout the world. Binomial classification in its simplest form is away of naming a species by means of two names both in Latin. Latin wasoriginally used because it was the language of the founders of theclassification system, like Carolus Linnaeus, but it continues to beused presently because it is a “dead language”.
This means that it is nolonger changing or evolving, so it stays the same and can be useduniversally, without confusion. Carolus Linnaeus (see Appendix A, Image1) first introduced binomial classification, which is why he is known asthe father of the modern day classification system. In Binomial classification the first name, which begins with a capitalletter is known as the Genus it is always capitalized. The genus is agroup of species more closely related to one another than any othergroup of species. The genus is more inclusive than the species becauseit often contains many species.
The second part of the binomialrepresents the species itself and is always printed with all letters inlower case. A species is a group of individuals that are alike in manydifferent 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 thespecies leo to form Panthera leo, the Lion. Likewise, Panthera iscoupled with tigris, to form Panthera tigris the Tiger. In simplifiedterns both the Lion(see Appendix A, image 2) and Tiger share commontraits and a common genus – Panthera, whilst clearly remaining separatespecies.
To allow further subdivision, the prefixes sub- and super- maybe added to any category. In addition, special intermediatecategories-such as branch (between kingdom and phylum), cohort (betweenclass and order), and tribe (between family and genus)-may be used incomplex classifications. Closely related species are a genus, closely related genera (plural formof genus) are grouped together in a family. Closely related families aregrouped into an order, and so on, into more inclusive categories, orlevels in the classification hierarchy. Taxonomic Hierarchy Approximately one and a half million species have been classified andthere are estimates that over five million species remain to bediscovered. For biologists to order this mass of information, ascientific system called taxonomy was introduced.
The basic idea is togroup species with similar characteristics together into families, andto group the families together into broader groupings. To this end, thetaxonomic categories where devised, and they create the taxonomichierarchy. The hierarchy goes (with an example):*CategoriesExample KingdomAnimalia Phylum (Plural = Phyla)Cordata*In plants, this category is often called a division*ClassMammalia OrderCarnivora Family Canidae GenusCanis Species Lupus (the Wolf)Every species is in only one genus. Similarly, every genus is in onlyone family, and so forth up the hierarchy. The most inclusive categoryfor classifying groups of similar organisms is the Kingdom. It is arguedexactly how many Kingdoms there are though.
Up until recently, only twokingdoms were generally used, the plant and animal kingdoms. Now howeverthere are 5 established kingdoms and one controversial unofficialkingdom. 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. Theseare acellular entities with many of the properties of other life forms,but are genetically and structurally too dissimilar to the speciescategorized above to fit into that scheme of taxonomy.
Although this system is complex and intricate at times, itsuniversality makes it a necessity. With out the system presently in usethe world would be years and years behind in their task to name all ofthe living organisms on earth. This system is great but it is alwayspossible that some new finding could cause the system to evolve tobecome more inclusive. This system is by no means set in stone, andLinnaeus would probably be astounded to see the way that it has evolvedsince his original system. Appendix ACarolus Linnaeus (Image1)Panthera leo (Image 2)BibliographyBerkely 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
