Animal classification system
Basic Of Animal classification system
The terms systematics, taxonomy and classification are often used interchangeably. G. Simpson (1961) has distinguished these terms as follows
Systematics ( Gk. systema – order or sequence )
This term was coined by Linnaeus. The study of diversity of organisms, their comparative and evolutionary relationship based on comparative anatomy, ecology, physiology, biochemistry and other field is known as systematics.
Taxonomy (taxis – arrangement, nomos – law)
This term was coined by de Candolle (1813). It is the branch of biology which deals with the study of principles and procedures of classification, nomenclature and identification. Taxonomic knowledge requires the study of morphology, cytology, embryology, biochemistry, genetics and ecological relationship etc. Linnaeus is considered as father of taxonomy. But according to Turril taxonomy can be of following types. Biology Doubts from Physics Wallah.
Taxonomic study deals with collection and identification of organisms on the basis of gross morphology, compilation of flora and monographs.
Taxonomic study deals with arranging species into natural classification on the basis of all available evidences.
Taxonomic study deals with biological aspects of taxa like intraspecific population, speciation, rate of evolution and evolutionary trends.
It is a subtopic of taxonomy or systematics that deals with arranging organisms into groups or categories according to a systematic plan on the basis of their similarities, differences and relationships.
Need for classification
Biological classification is the scientific procedure of arrangement of organisms into groups on the basis of their similarities and dissimilarities and arranging them in a hierarchy of categories. Following are the reasons which satisfy the need for classification
- Classification helps in knowing the relationship among different groups of organisms.
- There are about 1.25 million animal species have been discovered, identified and described so far, they have diversity in structure, habits, habitats and mode of life, it is not possible to study every organism but study of one or two organism of a group can give sufficient relative information about essential features of the group.
- Location of different organisms is different. It means all kinds of organisms do not occur in one locality.
- Fossils cannot be studied without the help of a good system of classification.
- Relationship and simplicity or complexity found in different organisms of various texa explains the evolution.
System of biological classification
There are three main systems of classification
- Artificial system of classification
- Natural system of classification
- Phylogenetic system of classification
Artificial system of classification
All early systems of classification given by Aristotle, Theophrastus, Pliny, Bauhin, John Ray etc were artificial. In this system of classification habit, habitat and a few morphological characters are used for grouping of organisms.
For example, Aristotle (384 – 322 BC) divided animals into two groups, Enaima (With red blood) & Anaima (Without red blood). Enaima are further divided into Ovipera (Egg lying) & Vivipera (Giving birth to young ones). Pliny divided animals into flight and non flight animals. Artificial systems are simple and easy but they have several draw backs like it does not take into the consideration the process of evolution, closely related organisms get separated into different groups, organisms of different affinities may come in the same group and the traits used for artificial system are liable to change.
Natural system of classification
In this system of classification organisms are classified according to their natural affinities through the use of all important permanent characteristics like structure, cytology (chromosomes), reproduction and biochemistry. These characters are useful in bringing out homology. The first natural system of classification for plants was proposed by Schimper (1879), but most important and last natural systems of classification for seed plants was developed by Bentham (1800 – 1884) and Hooker (1817 – 1911) in the treatise called Genera Plantarum. The first natural system of animal classification was developed by Linnaeus in his book “Systema Naturae” (10th edition, 1758).
Phylogenetic systems of classification
This system of classification came into existence after the acceptance of doctrine of evolution and natural selection given by Charles Darwin. This system considers evolutionary relationships of organisms. Phylogenetic system of classification was first proposed by Engler (1844 – 1930) and Prantl (1849 – 1893) in their monograph Die Naturlichen Pflanzen Familien (1887 – 1899).