Write in brief about progressive changes in animal classification.

Explanation

i. Different scientists have tried to classify animals, from time to time.
ii. Greek philosopher Aristotle, was the first to classify animals on the basis of criteria like body size, habits and habitats.
iii. This method of classification proposed by Aristotle is known as 'artificial method'.
iv.Artificial method of classification was followed by Theophrastus, Pliny, John Ray, Linnaeus, etc.
v. In accordance with the developments in science, references changed and thus the criteria of animal classification also changed.
vi. Later, the natural system of classification was followed in which animals were classified according to criteria like body organization, types of cells, chromosomes, bio-chemical properties, etc.
vii. By then, the system of classification based on evolution was brought into practice. This system of classification wad used by Dobzhansky and Mayr.
viii. Carl Woese proposed the six kingdom classification system. This system divides prokaryotes into two kingdoms and the eukaryotic kingdoms remain in the third domain thereby, forming six kingdoms viz. - Eubacteria, Archaebacteria, Protista, Fungi, Plantae and Animalia.
ix. The five kingdom classification system, proposed by Robert Whittaker is in use now. According to this classification system, animals are classified based on the criteria like body organization, body symmetry, body cavity, germinal layers, segmentation, etc.