Classification of living organisms.

Before enter in the classification methods themselves, we ca understand a little bit of the past and nature of classifications.

The Editorial Medica Panamericana defines classifications as "hypotheses that biologists continually test through their work, using a classification system for naming and grouping the known species in a logical, objective, consistent and not redundant manner".


Of course the base of this classifications are the characteristics that living organisms have, but... Why to organize them?


Since there are millions of living organisms, the scientists have had to group them to make easier their study: 

•  Aristotle's Classification . He consider no more than a few hundreds of species: he classify them in Animals Kingdom and Plants Kingdom; also he made a division in the first kingdom, differentiating the ones who have red blood and the ones who haven't.
• Linné's Classification. He was a Swedish botanist from the 18th century. He established a hierarchy of groups named "taxa". Each "superior taxon" involves one or more "inferior taxons".

And this is the origin of the most recognized and standardized classification of organisms nowadays: The scientific classification. It consider 8 taxons which are (from bigger to smaller):

1. Domain
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus 
8. Species

It also proposes, as Linné, the binomial nomenclature, to name the organisms, which consist in call a living organism with its genus name and its specie name.

This classification of course involve a detailed observation not only phisical characteristics of organisms but also genetic characteristics, turning it in a very specific, but exclusive-scientific classification.

Turning back to the nature of classifications, some ways to group living organisms have to do with the easily identifiable characteristics that display: biped or quadruped; oviparous or viviparous; herbivore or carnivore, and those are commonly used in practical cases, unless are not as specific as the scientific classification.