Classification of living organisms

The main representative of the classic period of taxonomy, the discipline that classifies and identifies all living creatures, was Carolus Linnaeus (Linneo) (1707-1778), who divided living creatures in two kingdoms animal and vegetal, or the Animalia and 

In the 18th century there was no alternative but to use a strictly morphological approach, so that the more structural traits shared by different organisms (i.e., the number and placement of limbs, the shapes of leaves, or internal organs), the closer their taxonomic relationship. 

Two major factors have altered the basis on which taxonomies are constructed and their uses established. The first was Charles Darwin s theory of evolution. The second was the advent of new techniques for studying the physiology, embryology, and biochemistry of living creatures. 

Evolutionary thought and theory since the time of Darwin have created a new function for taxonomic classification to provide a framework for the study of evolutionary relationships. The overwhelming evidence we have that all organisms on Earth are related by common descent from some of the first cells, has led to different methods for tracing the family trees or phylogenetic trees of living and fossil organisms. 

The discipline that attempts to understand the evolutionary interrelationships of living things, trying to interpret the way in which life has diversified and changed over time is systematics, while taxonomy is primarily the creation of names and groups. 

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Parker, S.P. (Editor in Chief) Synopsis and Classification of Living Organisms McGraw-Hill New York, 1982, Volume 1, pp. 1-1166, Volume 2, pp. 1-1232. 

Systems of Classification of Living Organisms Great Steps in Chemical and Biological Evolution... 

The third edition of Five Kingdoms by Margulis and Schwartz (1998) gives an excellent presentation of the evolution of the concepts underlying various systems for the classification of living organisms. 

In Chapter 1 we discussed the importance of the structure of the cell membrane in the classification of living organisms, and pointed out that there is always a double layer of phospholipids whose cohesion is provided by stabilizer elements, which may be long-chain glycerol ethers, carotenoids, hopanoids or sterols. The structural differences observed in sponge membranes are considerable, particularly with regard to phospholipid fatty acids and sterols. 

Table 3-3 Classification of the major groups of living organisms...

Members of the five different kingdoms of the classification system of living organisms often differ in their basic life functions. Here we compare and analyze how members of the five kingdoms obtain nutrients, excrete waste, and reproduce. 

A preliminary, operational definition of the solid state is given within the box of Fig. 1.6. It will be expanded upon and linked to the material properties throughout the book. For materials, the transitions between solid and liquid are basic and determine their utility. Similarly, the evaporation characteristics need to be known to choose a molecule for a given application. The new classification scheme for molecules of Fig. 1.6 is, thus, much more useful than the earlier, arbitrary distinction that rehed upon the abihty or inability of living organisms to synthesize a particular substance. The bottom brackets give a rather unique explanation of the glass transition which is detailed in Sect. 2.5. 

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