Write in broad about progressive changes in animal classification
Answers
Different scientists have classified animals from time to time.
1. Taxonomy is the science of how living things are grouped together. Another name often used for taxonomy is classification.
2. Greek philosopher Aristotle classified animals by criteria like body size, habits and habitats. His method of classification was known as “Artificial Method”. This method was also followed by other scientists like Theophrastus, Pliny, John Ray, Linnaeus etc.
But, unlike Aristotle, Linnaeus divided kingdom into five levels: class, order, genus, species, and variety. Organisms were placed in these levels based on traits, including similarities of body parts , physical form such as size, shape, and methods of getting food. He suggested a binomial naming system and it has two parts. The first part of the species name identifies the genus to which the species belongs; the second part identifies the species within the genus.
3. Later on “Natural System of Classification” was followed based on various criteria like body organization, cell types, chromosomes, bio-chemical properties etc.
4. Another system based on evolution was used by Dobzhansky and Meyer.
5. Robert H. Whittaker in 1969 has classified the living organisms into five kingdoms. Living things can be classified into five major kingdoms - Kingdom Animalia (are eukaryotic and multicellular but have no cell wall or photosynthetic pigments), Kingdom Plantae (re eukaryotic and multicellular organisms), Kingdom Fungi (are eukaryotic organisms that can be multicellular or unicellular), Kingdom Protista (are eukaryotic and can be unicellular or simple multicellular), Kingdom Monera (Bacteria, prokaryotic, unicellular organisms).
The five-kingdom classification has certain drawbacks also, particularly with reference to the lower forms of life.