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Taxonomy of Lower Non-Chordata

Protozoa

Porifera

Coelenterata

Platyheiminthes

Aschelminthes

Annelids

Arthropods

Mollusca

Echinodermata

Protochordata

Concept of Taxonomy

The study of identification and relationship living organisms is called systematic. The term was used by Linnaeus( 1707-1778). The branch of biology dealing with identification, nomenclature and classification of organisms is called taxonomy. It is derived from Greek words (taxis, arrangement, and nomos law). Structural similarity or homology forms are the basics of classification. The classical systematics (old systematic) was first employed by Plato and Aristotle and was accepted by Carolus Linnaeus. His system has evolved over time. The Linnaean system designates five such classifications: flora, fauna, fungi, prokaryotes, and protoctists. Depending on the person studying and reviewing the taxonomy of Phyla in Zoology, these trees may different from especially with regards to ongoing research in many fields of study. Within species, further units may be recognized. Animals may be classified into subspecies (for example,Homo sapiens sapiens, modern humans) or morphs (for example Corvus corax variusmorphaleucophaeus, the Pied Raven). Plants may be classified into subspecies (for example Pisum sativumsubsp, sativum, the garden pea) or varieties (for example,Pisum sativumvar, macrocarpon, snow pea), with cultivated plants getting a cultivar name (for example Pisum sativumvar, macrocarpon'Snowbird'). Bacteria may be classified by strains(for example Escherichia coli, a strain that can cause food poisoning).
Taxonomy is the one of the oldest and most fundamental branch of biology. Though enough work has been done in other branches even the importance of taxonomy cannot be ignored. New species and types of animals and plants are being identified every day and their classification and characters are studied with the help of taxonomy. In addition to this, the use of scanning, electron microscopy and the information generated by others fields of science such as ecology, cytology, genetics, biochemistry, molecular biology specially DNA, animals are being restudied and replaced in the phylogenetic tress.
Trend
The concept of new systematic was given by J.AHuxley(1940). It deals with sub species and populations to explain population systematically. The development of modern taxonomy started during the 1930s. During this period, taxonomy was based on population studies. E. Mayr (1942) considered species as “groups of interbreeding natural populations”. His book ‘New Systematics’ became a landmark in the history of taxonomy. The taxonomists were forced to accept species as a ‘population’. Hence, the taxonomist started moving from the laboratory to the field. Morphological characters were studied along with other characters as behavior, sound, ecology, genetics, zoogeography, physiology, and biochemistry. Thus, taxonomy was transformed into ‘biological taxonomy’.
The great Swedish naturalist Linnaeus (Caroli Linnaei) (1707 - 1778) exerted an important influence on further advancement in taxonomy. Hence, he has been called the father of taxonomy. In 1758 he published his famous book, Systema Naturae. He first introduced the hierarchic system, both in animal and plant kingdoms. He followed four categories namely class, order, genus, species for the animal world. Michael Adamson (1727 - 1806), a French botanist, stressed that classification should be based on as many characters as possible. His concept helped to develop a new type of taxonomy called ‘Numerical Taxonomy’. Lamarck (1744 - 1829) made the first attempt to improve Linnaean system. He published seven volumes of his ‘Histoire Naturelle des Animaux sans Vertebres’. Cuvier (1769 - 1832) insisted that extinct fossil forms should be included in the table of classification. He divided animals into four branches. They are Vertebrata-fishes to mammals, Mollusca-molluscs and barnacles, Articulata-annelids, crustaceans, insects and spiders and Radiataechinoderms,nematodes and coelenterates. Charles Darwin in 1859, published his famous work ‘Origin of species’. The new evolutionary concept of Darwin had an immediate acceptance among biologists. The influence of evolutionary ideas, taxonomy was studied as an important evidence in favor of evolution. The taxonomists were encouraged to learn that evolution theory of Darwin gave meaning to their classifying activities.
The New systematically considers besides morphology, other aspects also like ecology, biochemistry, physiology, cytology, and genetics. The systematic has led to new branches of taxonomy like morpho-taxonomy based on morphological characters, Kary taxonomy based on nucleus and bands on chromosomes. Cytotaxonomy based on cytoplasm ( cytochrome C), experimental taxonomy based on experiments determining genetic interrelationships, biochemical taxonomy on the basis of biochemical studies, chemotaxonomy-based on particular chemicals like secondary metabolites and numerical taxonomy or phonetic or adansonia taxonomy explained by Adanson(1963) based on statistical methods employed in classification.
Significance Of Taxonomy
More then student of biology comes across taxonomy during his course of study as one of the important topics. The earth’s biodiversity is huge, there are hundreds of types of animals and plant. So it is difficult to study them all in a simple manner. So taxonomy was made to group animals and plants based on a set of characters.
  • The convenience of study
    Out of millions of types of organisms it is difficult to study each of them. The study of selected animals of a particular group gives an idea about the remaining animals of that group, for example, the study of rabbit gives the knowledge about all animals of class mammalian.
  • Knowledge of sequence of evolution
    T
    he sequence of evolution of animals, like an evolution of sponges from single - celled protozoa and that of arthropods from annelid , could only be known through.
  • Knowledge of affinities
    The knowledge about relationships or affinities of different animals with other animal species comes from classification.
  • Knowledge of connecting links
    The transitory stage between two groups of animals, is known as connecting links. It gives the sequence of evolution of animals. With the help of classification, definite position of connecting links can be made clear.
  • Knowledge of adaption
    By classification we come to know about such characters of animals with which they adapt to an environment.
  • Knowledge of phylogeny
    Animals of one group are evolved from a common ancestor is known through classification because this is based on phylogeny. We know that all animals of class mammalian have evolved from one common ancestor.

 

Reference
Aggarwal Sarita. A Text Book of Biology,New Delhi.: Madhuban Educational Books, 2011.
Bhamrah, H.S., and Kavita, Juneja. A Text Book of Invertebrates, New Delhi: Anmol Publications Pvt Ltd, 2011.
Jordan E.L. and P. S., Verma. Invertebrate Zoology, New Delhi,: S. Chand and Company Pvt. Ltd., 2011.
Kotpal, R. L.,. Modern Text Book of Zoology: Invertebrates, New Delhi, India: Rastogi Publications,2011.
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